new patient centres coeliac disease - sa pathology

Supporting Training and Medical Research

www.imvs.sa.gov.au

N e w s l e t t e r

Reference interval changes 2 New Patient Centres 3 Coeliac disease 4 Dabigatran inhibition of coagulation assays 6 ANA interpretation 8 FMH screening 10 New genomics facility 11 Point of Care 12

INSIDe

7 72 0 1 2

IMVS NewsletterPublished by IMVS

Editorial CommitteeJohn Bahnisch, Mark Fitz-Gerald, Ming Qiao, Dianne Zurcher, Madelyn Duckmanton and Alexandra Race

[email protected]

DesignSue Dyer Design

PhotographyIMVS Photo and Imaging

PrintingFivestar Print

Cover: One step closer to personalised medicine, a new genomics facility opens at IMVS Pathology Full story page 11

on may 23, 2012 we said farewell to Professor Ruth Salom, the inaugural executive Director of SA Pathology which trades as IMVS Pathology. Over the last four and a half years Professor Salom has worked tirelessly to develop a statewide pathology service of which South Australia can be proud. We have achieved a 25% efficiency gain, and worked to provide high quality services as close as possible to our clients.

To achieve this aim, we have commissioned a new laboratory at Modbury Hospital and opened 15 new patient collection centres across metropolitan and regional South Australia. We have also established the Centre for Cancer Biology and developed the IMVS Pathology iPhone App and website. In addition the new child-centric patient centre at Women’s and Children’s Hospital is now open, and later in the year, the new cancer genomics facility will open.

In her final words to staff Professor Salom said, “I can without doubt say that it has been the most fulfilling work that I have ever done”.

Professor Salom has been instrumental in driving these achievements and we would like to thank her for her hard work and dedication. We wish her well as she returns to her home in Melbourne and to her previous role as Director of Pathology for the Victorian Cytology Service. We look forward to a time of consolidation and continuing to provide the people of South Australia with a quality pathology service that supports training and medical research.

Thank you for reading the IMVS Newsletter and as always we welcome your feedback and suggestions for future articles.

Dr Janice Fletcher

IMVS IS headed by ProfeSSor ruth SaloM a MedICal graduate who haS SPeCIalISed aS a SurgICal PathologISt.

From the Executive Director

IMVS Newsletter > 77 – 2012 PAGE 2

From theinside

ISSN 0813 – 1643

DR JANICE FLETCHER, A CLINICAL GENETICIST AND GENETIC PATHOLOGIST, IS DEPUTY DIRECTOR OF SA PATHOLOGY AND CURRENTLY ACTING EXECUTIVE DIRECTOR.

Serum tryptaseFollowing a clinical review the reference interval for serum tryptase has changed; normal tryptase values are now less than 12 ug/L, patient results will not be affected.

Serum tryptase is used as a marker for anaphylaxis and mastocytosis. Serum tryptase levels are elevated for three to six hours after an event before returning to normal levels after 14 hours. With mastocytosis elevated levels persistent.

This reference interval change will improve the specificity of the test and therefore the clinical significance of an abnormal result.

Reference interval changes

If you have any questions regarding the following reference interval changes please contact A/Professor Bob Heddle, via IMVS Pathology enquiries on (08) 8222 3000.

Serum rheumatoid factorTo improve turnaround times for results IMVS Pathology changed the method for measuring serum rheumatoid factor in March 2012. Serum rheumatoid factor is now measured on the ADVIA 2400 platform with a new reference interval of less than 14 IU/mL; previously normal was less than 20 IU/mL.

Diabetic antibody IA-2Following changes introduced by the test kit manufacturer to improve its diagnostic performance IMVS Pathology has changed the reference interval for the Type 1 diabetic antibody, anti IA-2, in serum.

Anti IA-2

Anti GAD

OLD

<20 IU/mL

<10.0 IU/mL

NEW

<10.0 IU/mL

<10.0 IU/mL

Toxicology accreditation

IMVS Pathology provides a NATA accredited service (AS/NZS 308.2008) for the detection of drugs of abuse in urine. For more information please contact Marketing on (08) 8222 3222 or email [email protected]

www.imvs.sa.gov.auIMVS Newsletter > 77 – 2012 PAGE 3

Skin scrapings

IMVS Pathology offers a fungal scraping test collection service at all of its Patient Centres including our regional centres. Bookings are not required, so when you next require a fungal scraping skin test, send your patient to an IMVS Patient Centre that’s convenient to them. We’re part of your community, visit www.imvs.sa.gov.au for a list of locations.

Endomysial antibody requests

Endomysial antibodies (EMA) will be discontinued as part of our routine screen for coeliac disease as the substrate used in the production of the EMA test is increasingly in short supply.

The EMA test will be replaced with anti tissue transglutaminase (TTG) IgA antibodies which have a comparable clinical performance. Our recommendation for general screening of coeliac disease will now be TTG and deaminated gliadin (AGA) IgG antibodies, which is consistent with the national testing guidelines. EMA is however useful for follow up of indeterminate TTG results, and we will still perform the test for this group of patients.

If you require EMA in addition to TTG, or as an alternative for your patients, please contact us.

Regional

Barmera Located within Barmera Medical CentreHawdon Street, BarmeraMonday, Tuesday and Friday 8:30am to 11:30am

Kapunda32 Hill Street, KapundaMonday – Friday 8:30am to 12:30pm

Tanunda13 Mill Street, Tanunda Monday – Friday 8:30am to 12:30pm(from 20 August 2012)

NoarlungaNoarlunga GP Plus Super Clinic20 Alexander Kelly Drive Noarlunga CentreMonday – Friday 8:00am to 4:00pm

Middleton Millhouse Medical Centre 5 Goolwa Road, MiddletonMonday, Wednesday and Friday 8:00am to 11:00am

Metropolitan

Modbury Modbury GP Plus Super Clinic77 Smart Road, ModburyMonday – Friday 8:30am to 12:30pm

New Patient CentresFor more information about IMVS Pathology Patient Centres visit www.imvs.sa.gov.au or phone enquiries on 8222 3000.

Victor Harbor - Goolwa Road

Mill

Tce

MiddletonCaravan Park

IMVS

Alexander Kelly Drive

Beach Road

Goldsm

ith Drive

IMVSEntrance

NoarlungaHealth Service

Car park

Car park

IMVS at GP PlusSuper Clinic

GP Plus

Tea Tree Plaza

Smart Road

ModburyHospital

Hatherleigh Ave

Car Park

IMVS

ECG screening

The following IMVS Pathology Patient Centres now offer an ECG screening service for non-urgent asymptomatic patients with a result turnaround of 24 to 48 hours. A referral is required however appointments are unnecessary.

Symptomatic patients should be sent to an appropriate hospital emergency department.

Blackwood Shop 2A Magnet Shopping Centre Coromandel Parade

Elizabeth GP Plus, 16 Playford Boulevard

Goolwa 2/26 Cadell Street

Modbury Hospital Smart Road

North Adelaide North Adelaide Village Shopping Centre 81 O’Connell Street

Stirling Suite 5 14 Druid Avenue


While accounts of coeliac sprue date back to the first century AD, the link with gluten was first characterised in the late 1940s. The wartime shortage of wheat, and the adoption of a surrogate gluten free diet led to improvement for children with diarrhoea and failure to thrive. When cereal supplies were restored their condition deteriorated.

We now recognise that CD is much more common than first thought. Data from the UK reveals that the most common age group diagnosed is between 30 and 45, with more sufferers over 60 than under 16.

The illness is most common in people of European, Middle Eastern and Indian backgrounds. There is debate over mass screening in Caucasian populations where the disease incidence approaches 1%.

Symptoms

Clinical symptoms vary according to age making CD difficult to diagnose. Some individuals have no symptoms while in others the symptoms may mimic other diseases. Classically CD may present with diarrhoea, irritability and failure to thrive in infants and young children, or diarrhoea, steatorrhoea, weight loss, abdominal bloating and flatulence in older children and adults (Table 1). More often, it presents as a milder form of disease with atypical symptoms and only anaemia or osteoporosis.

Coeliac disease (CD) is an autoimmune disorder of the small intestine triggered by an intolerance to gluten-containing foods, such as phylogenetically related cereals, wheat, rye and barley.

High risk populations for CD (Table 2) include those with insulin dependent diabetes, Sjogren’s syndrome, Down’s syndrome, IgA immunodeficiency and short stature children. About 5% of patients with insulin dependent diabetes have been reported to have coeliac pathology. The same prevalence has been reported in

Down’s syndrome and to a lesser extent autoimmune thyroid and liver diseases and ulcerative colitis. IgA deficiency is common in CD being found in 10% of patients.

The Gastroenterological Society of Australia recommends screening patients in high risk populations.

Table 1: Clinical features of coeliac disease

Chronic diarrhoea or alternating bowel habit

Unexplained weight loss

Abdominal distension, unexplained abdominal discomfort

Apthous ulceration

Steatorrhoea

Prolonged, unexplained fatigue

Arthralgia

Iron or folate deficiency

Unexplained abnormal liver function tests (elevated transaminases)

Idiopathic osteoporosis

Short stature/failure to thrive /delayed puberty in children

Possible clinical features

Polyneuropathy/ataxia

Infertility/recurrent abortions

Table 2: Clinical associations with coeliac disease

IgA deficiency

Other autoimmune disease:

Sjogren’s syndrome

Type I diabetes mellitus

Autoimmune thyroiditis

Autoimmune liver diseases

Alopecia

Addison’s disease

Myaesthenia gravis

Rheumatoid arthritis

Downs Syndrome

Turner Syndrome

Williams Syndrome

Congenital heart defects

CoeliacDisease

When in doubt – leave it out

DR Tiffany HugHes – CONSULTANT PAThOLOGIST Immunology


Diagnosis

1 Diagnosis of coeliac disease is based on a combination of specific serology and an abnormal intestinal biopsy. All testing must be done while the patient is on a gluten-containing diet.

2 Clinical success of a gluten-free diet.

3 Screening of first-degree relatives to detect asymptomatic disease.

4 Monitoring dietary compliance with serological markers.

Coeliac serology Serological screening tests recommended include:

nanti-tissue transglutaminase (TTG) IgA antibody

n anti-deaminated gliadin (GLI) IgG antibody.

The combination of these two tests gives a high degree of sensitivity and specificity, and negates the need to test for serum IgA.

Patients should be on a normal diet when tested; a gluten-free diet may give false negative results.

InterpretationPositive serological results suggest further investigation for coeliac disease. An upper endoscopy with biopsy of the distal duodenum or jejunum, including multiple sampling, remains the gold standard for diagnosis of all patients.

An isolated borderline positive TTG or GLI result should be interpreted with caution as it may represent a non-specific finding that may be found in a range of intestinal disorders. In this situation further investigation should be undertaken where there is high clinical suspicion.

Negative serology makes active coeliac disease less likely, but cannot entirely exclude the diagnosis. A biopsy should still be undertaken if there is a high clinical suspicion of CD. This is particularly important in children under two years of age, where the immune system is still developing.

Genetic testingThe development of CD is currently thought to be determined by both genetic predisposition and an autoimmune trigger such as an infectious agent, stress and pregnancy. All coeliac patients are HLA DQ2 or DQ8 genotype positive.

Selective genotyping for HLA DQ2 and DQ8 is useful to exclude the likelihood of developing CD in first-degree relatives of patients and in high risk groups. However HLA DQ2 is also present in roughly 25% of the

caucasian population of whom less than 4% will ever develop CD. In family members or high risk groups, the absence of DQ2 or DQ8 excludes coeliac disease now and in the future.

Coeliac genotyping is a Medicare rebatable test.

nHLA-DQ2/DQ8 positive – CD is not excluded

nHLA-DQ2/DQ8 negative – CD is excluded

contined on page 7

Gluten Free foodsmeatfishpoultryfruitvegetableslegumesmilkcheese – block, creamed, cottage, fettaeggsnutsrice

polentabuckwheatsorghumquinoaamaranthsagomaizecornmealsoybesanglucosecaramel colouring (150)

dextrosepure icing sugarwine vinegarbalsamic vinegarplain potato chipsteacoffeeciderwine

®

Foods to avoid

*check ingredients as may be derived from gluten containing sources

soy sauceWorcestershire saucebeer, lager and alesmalted milk drinks e.g. Milolemon barley cordialprocessed meats*hydrolysed vegetable protein*textured vegetable protein*maltodextrin*modified starch*cornflour*thickeners (1400-1450)*commercial sauces*ice cream*lollies*gravy*stock cubes*medications*

wheatbarleyryeoatstriticalesemolinacouscousspeltkumatburghulbrewers yeastyeast extractmalt vinegarpretzelsicing sugar mixturedry roasted nutslicoricecheese spreads

®


Dabigatran etexilate is an oral anticoagulant which has recently been approved by the Therapeutic Goods Administration for prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation. Although not yet Pharmaceutical Benefits Scheme listed for this indication, a large number of patients use Dabigatran etexilate through a patient familiarisation program.

Pharmacokinetics

Dabigatran is a direct thrombin inhibitor. The onset of anticoagulant effect after administration is within 30 minutes of administration, with peak plasma concentration (approximately 150 to 200 ug/L) and anticoagulant effect achieved within 2 to 3 hours. Trough levels of approximately 50 ug/L occur approximately 12 hours post dose.

ContraindicationsDabigatran is renally cleared and in individuals with normal renal function has a half-life of 12 to 14 hours. Importantly clearance is delayed in patients with renal impairment and the half-life in patients with a creatinine clearance (Cr Cl) of less than 30 mL min is less than 24 hours. Use of the drug is contraindicated in these patients and care should be taken in prescribing it to elderly patients or those with impaired renal function as outlined in the drug product information sheet.

Assay affects

Dabigatran as a direct thrombin inhibitor may interfere with coagulation assays.

Prothrombin time (PT)At therapeutic concentrations (50 to 200 ug/L) Dabigatran has little effect on PT and therefore INR. At supra-therapeutic concentrations the INR may be as high as 2.0.

Activated partial thromboplastin time (aPTT)aPTT is prolonged with increasing Dabigatran concentration. At peak concentration aPTT is approximately twice that of a normal patient; whereas a 1.5 fold increase is seen at trough levels (12 hours post dose). A normal aPTT suggests that minimal drug is present. A significantly prolonged aPTT of greater than 65 at trough (12 hours post-dose) or 80 seconds at any time suggests that the drug is present excessively.

Thrombin time (TT)This assay is particularly sensitive to the effect of Dabigatran and a normal TT can be used to exclude the presence of a clinically significant level of drug.

Dabigatraninhibition of coagulation assays

Dabigatran assay

Measurement of Dabigatran levels is not routinely required in all patients who use it. There is no proven relationship between coagulation test results and therapeutic effect or safety of the drug.

Reasons for measuring Dabigatran levels may include;

n Measurement at the time of anadverse event to establish if thecomplication was related toeither excess drug (in the event of a bleeding episode) or insufficientdrug level (in the event of athrombotic complication).

n Patients requiring urgent or semi-urgent surgery to establish thesafety of proceeding with aninvasive procedure. Generallymost procedures can be performed safely if the drug concentration is less than 50 ug/L. A normal aPTT or TT can also be used as an indicator of minimal drug concentration. It is recognised in some circumstances that surgery may need to proceed urgently regardless of drug level, and in these circumstances specialist haematologist advice should be sought. ¥

Dr Simon mcrae – consultant pathologist Haematology

Liz Duncan – head of unit Haemostatis & Thrombosis


Copy To

Patient Last Name Is the patient of Aboriginal descent? Yes □ No □

Given Name(s)

Date of Birth

Medicare/Repat Number

Patient Address

Postcode

Sex Patient UR Number/Code

✘

✘ / /

Requesting Doctor Details

□ Repeat Request Form

Clinical Notes □ Fasting □ Non Fasting

Date of onset of illness

BLUE TOP

WHITE TOP

GREEN TOP

PURPLE TOP

GREY TOP

24H UR MSU SWAB FAEC SLIDE HISTO FUNGAL OTHER

Tests Requested

Specified APP Yes / No Name ____________________________________

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✘

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Patient Status (Hospitals)

Was or will the patient be at the time of service and

when the specimen is obtained:

□ a private patient in a private hospital or approved

day hospital facility

□ a private patient in a recognised hospital

□ a public patient in a recognised hospital

□ an outpatient of a recognised hospital

Your doctor has recommended that you use IMVS Pathology. You are free to choose your own

pathology provider. However, if your doctor has specified a particular pathologist on clinical grounds

a Medicare rebate will only be payable if that pathologist performs the service. You should discuss

this with your doctor

Medicare Benefits (Section 20 A Health Insurance Act 1973). I offer to assign my right to benefits

to the approved pathology practitioner who will render the requested pathology service(s) and any

pathologist determinable service(s) established as necessary by the practitioner.

□ Not for Public Health System Distribution

I have verified FULL NAME, DOB and URN on the sample label and request form

verbally with the patient and/or checking the patient’s ID band.

Collector’s Signature ................................................

..............................................

................

Specimen Collected ...............................................

..............................................

.................

/ / : H rs

✘

✘ / /PATIENT SIGNATURE AND DATE

PRACTITIONER’S USE ONLY

(Reason patient cannot sign)

Hospital RGH

Ward

Toll free 1800 188 077 Fax 08 8222 3538

Frome Road Adelaide SA 5000 www.imvs.sa.gov.au

SA PATHOLOGY trading as IMVS APA

ENQUIRIES 08 8222 3000

PM

G S

AP

RG

PA

D08

73

□ SD □ Rule 3 exemption

*12345678*12345678

*12345678*12345678

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B-SAPGXFRM0873 Part 1.indd 1

11/1/11 11:14:23 AM

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11/1/11 11:14:23 AM

Perforation

Perforation

FULL NAME:

D.O.B./URN

FULL NAME:

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FULL NAME:

D.O.B./URN

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11/1/11 11:14:23 AM

SAPRGPAD0873.indd 1

10/04/12 3:35 PM

Specific guidelines on other aspects of clinical management of patients on Dabigatran such as peri-operative management and management of acute bleeding complications are available at www.sahealth.sa.gov.au/medicationsafety

When requesting Dabigatran levels please note the following important points:

n Collect blood into one blue top (citrate) tube, and send to the laboratory within 4 hours of collection.

n To compare your patient’s response to published studies collect at peak (2 hour post dose) or trough (before next dose).

n For urgent after-hours tests please call the Duty Haematologist on 8222 3000.

NEW DABIGATRAN TEST

At IMVS Pathology we have set up a new test to specifically measure Dabigatran levels.

n Ask for “Dabigatran assay” n State the time of blood collection, the drug dosage and the time of last dose.

On the request form

n Please state the reason for testing and degree of urgency to assist the laboratory in prioritising. We are able to provide same day turn-around-time for urgent requests.

Copy To Patient Last Name Is the patient of Aboriginal descent? Yes □ No □

Given Name(s)

Date of Birth

Medicare/Repat Number

Patient Address

Postcode

Sex Patient UR Number/Code

✘ ✘ / /

Requesting Doctor Details

□ Repeat Request Form

Clinical Notes □ Fasting □ Non Fasting

Date of onset of illnessBLUE TOP

WHITE TOP

GREEN TOP

PURPLE TOP

GREY TOP

24H UR MSU SWAB FAEC SLIDE HISTO FUNGAL OTHER

Tests Requested

Specified APP Yes / No Name ____________________________________

LIFT

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DOCTOR’S SIGNATURE AND DATE

□ URGENT Phone Fax

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✘ ✘ / /

Patient Status (Hospitals) Was or will the patient be at the time of service and when the specimen is obtained: □ a private patient in a private hospital or approved

day hospital facility □ a private patient in a recognised hospital □ a public patient in a recognised hospital □ an outpatient of a recognised hospital

Your doctor has recommended that you use IMVS Pathology. You are free to choose your own pathology provider. However, if your doctor has specified a particular pathologist on clinical grounds a Medicare rebate will only be payable if that pathologist performs the service. You should discuss this with your doctorMedicare Benefits (Section 20 A Health Insurance Act 1973). I offer to assign my right to benefits to the approved pathology practitioner who will render the requested pathology service(s) and any pathologist determinable service(s) established as necessary by the practitioner.□ Not for Public Health System Distribution

I have verified FULL NAME, DOB and URN on the sample label and request form verbally with the patient and/or checking the patient’s ID band.

Collector’s Signature ..............................................................................................................

Specimen Collected ............................................................................................................../ / : H rs

✘ ✘ / /PATIENT SIGNATURE AND DATE

PRACTITIONER’S USE ONLY(Reason patient cannot sign)

Hospital RGH

Ward

Toll free 1800 188 077 Fax 08 8222 3538Frome Road Adelaide SA 5000 www.imvs.sa.gov.auSA PATHOLOGY trading as IMVS APA

ENQUIRIES 08 8222 3000

PM

G S

AP

RG

PA

D08

73

□ SD □ Rule 3 exemption

*12345678*12345678

*12345678*12345678

*12345678*12345678

*12345678*12345678

B-SAPGXFRM0873 Part 1.indd 1 11/1/11 11:14:23 AM

*12345678*12345678

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B-SAPGXFRM0873 Part 1.indd 1 11/1/11 11:14:23 AMSAPRGPAD0873.indd 1 10/04/12 3:35 PM

Dabigatran assay

Collection 11.45amPatient on 150mg BDLast dose 8.00am todayGI bleeding - URGENT

contined from page 5

Endomysial antibodiesThese antibodies were the first diagnostic test for coeliac disease, and are now known to also recognise the tissue transglutaminase antigen. While it has good diagnostic utility in coeliac disease, it requires substrates that are difficult to obtain. Endomysial antibodies are of limited use in monitoring disease, as they take 12 to 18 months to become negative.

Endomysial antibodies have now been replaced by anti TTG antibodies and are no longer recommended.

Gluten-challengeThe need for gluten challenge has been largely superseded by diagnosis based on the combination of abnormal intestinal biopsy, abnormal serology and clinical response.

Management

The mainstay of treatment for CD is a life-long gluten-free diet. No medication will prevent intestinal damage.

It is important to emphasize that osteoporosis in coeliac disease is primarily treated by a gluten-free diet possibly with vitamin D supplementation and not with bisphosphonates.

Dietary compliance is best monitored with coeliac antibodies, particularly those antibodies positive at the time of diagnosis. In the majority of patients, they will disappear within six to nine months of introducing a gluten-free diet, and reappear with the reintroduction of gluten into the diet.

In a small proportion of adult patients however the intestinal damage may be irreversible and symptoms may persist despite being on a gluten-free diet. This is called refractory sprue and raises the suspicion of enteropathy associated T cell lymphoma. ¥

Coeliac Disease

Interpretation limitations

The ANA test is used to screen for systemic rheumatic diseases. Serum is initially tested at a screening dilution and a positive result reported as a titre with a nuclear pattern.

The choice of screening dilution is important. A negative result can be used to rule out disease whereas a positive result drives the need for further investigation. However the choice of screening dilution for ANA has been more historically than clinically based and varies between laboratories.

The clinical significance of a positive screen is complex. Reference intervals for ANA result interpretation are not clinically useful as the significance of a positive result varies according to age and the clinical presentation.

A low titre may be detected non-specifically in a range of inflammatory and neoplastic conditions and in a significant proportion of healthy individuals, particularly the elderly. Except where there are strongly suggestive clinical symptoms, further testing is unnecessary. However a low ANA titre in younger patients with suggestive clinical symptoms is more significant and warrants further testing. Generally the higher the ANA titre the more clinically significant the result.

ANA is also classified according to patterns observed. Binding of different

antibody specificities to intracellular structures produces different nuclear patterns, for example homogeneous, speckled, centromere, nucleolar etc. Different nuclear patterns are associated with a variety of autoimmune disorders. Some of these patterns are more clinically specific than others, for example anti- centromere antibodies are strongly associated with limited scleroderma.

Because of this complexity in interpretation ANA results must always be considered in conjunction with clinical presentation and other tests.

Likelihood Ratio

Pathology is littered with tests that claim to have a high probability of diagnosing certain diseases, that performed very well in preliminary studies in select populations but poorly when used in the real world of general practice.

Traditionally, the value of any diagnostic test is calculated by various statistical measures, sensitivity and specificity being the most commonly used. However, this does not indicate the usefulness of the result in clinical situations. Similarly positive and negative predictive values are dependent on prevalence of the disease in the population being tested. The rarer the condition, the more likely a negative test result is truly negative, and the less likely a positive test result is truly positive.

A more effective method of interpreting results is through LR (Likelihood Ratio), an expression of how the level of ANA can weaken (negative LR) or strengthen (positive LR) the diagnosis of Systemic Lupus Erythromatosis (SLE) or a related systemic autoimmune disease, given the pre-existing likelihood of that disease in a patient (the pre-test probability).

LR have several advantages, they:

n are not affected by disease prevalence in the population under study

n may be calculated at several levels

n provide an independent measure of the post-test probability with the pre-test probability.

interpretationInterpretation of antinuclear antibody (ANA) results is complex. ANA is present in greater than 95% of patients with systemic autoimmune diseases but there is a high prevalence of the antibody in a healthy population. This makes the use of reference intervals impractical. The Likelihood Ratio (LR) based on the probability of having or not having disease offers a more useful tool for clinical decision making.

ANA


DR PRaVin HissaRia – CONSULTANT PAThOLOGIST Immunology


The Clifford Prize for Cancer Research was awarded in November 2011, to Professor Vishva Dixit.

Professor Dixit pioneered studies that defined the framework of the cell death pathway. This has dramatically altered our understanding of the molecular events required for programmed cell death and pro-inflammatory signalling in cancer.

The Clifford Prize is awarded to a scientist whose contribution has made a global difference in the fight against cancer. The presentation is made biannually at the Centre for Cancer Biology’s international Barossa meeting.

Clifford Prize 2011

R E S E A R C h S P O T L I G h T

Screening dilution

LR was used to investigate the optimum screening dilution for ANA testing using samples referred from all medical practitioners, both general practitioners and specialists from both public and private practice. The results are summarised in Table 1.

A negative LR (probability of not having disease) less than 0.2 at the screening dilution is a very strong discriminator to rule out systemic autoimmune disease.

From Table 1, only 1/40 and 1/80 dilutions meet this criterion. Higher dilutions are not clinically useful to exclude disease and will miss patients with disease. Of the two dilutions, the 1/80 dilution has the higher positive LR and therefore higher probability of a positive result having disease.

A titre of 1/80 is the best screening dilution to exclude systemic autoimmune disease and is now being used routinely.

TITRE

TOTAL (N = 2315)

Pos LR Neg LR

1/40

1/80

1/160

1/640

1/2560

2.99

3.25

4.07

8.60

16.09

0.18

0.19

0.27

0.42

0.65

Table 1: ANA likelihood ratios by dilution

Positive result – significance

A positive LR 5 to 10 or greater will have a very strong effect on pre-to post-test probability. Table 1 shows that the positive LR (probability of having disease) increases with the ANA titre. An ANA titre of 1/640 or greater is associated with a greater likelihood of systemic autoimmune disease and requires further investigation. ¥

ANAANA is a screening test for diagnosis of systemic rheumatic diseases

In the absence of a very strong clinical suspicion, a negative ANA result gives good reassurance that there is no SLE or systemic rheumatic disease

A positive result however is not a diagnosis of any particular disease alone. In the context of a positive ANA, age and clinical suspicion of disease, further autoimmune testing is required to make the diagnosis

ANA titres often remain elevated in remission and do not necessarily reflect disease activity

ANA (and ENA) results do not reflect disease activity, and rarely is further testing warranted. A repeat test is of more value when the first test is negative due to the episodic nature of autoimmune diseases. A positive test is unlikely to need repeating

LR at various titres can be calculated to determine the post-test probability

Key Points


Fetomaternal Haemorrhage (FMH) screening is the recommended standard of care post delivery in RhD negative women delivering an RhD positive baby. The test is undertaken to ensure that the correct dose of RhD immunoglobulin (RhD-Ig) is administered following delivery. The standard post delivery dose is 625 IU, sufficient to protect against 6.25mL of foetal red cells.

The importance of

FMHScreening

In up to 3% of deliveries however, the FMH will be greater, hence the Royal Australian & New Zealand College of Obstetrics & Gynaecology (RANZCOG) recommend routine screening for these cases.

The following case highlights the importance of compliance with the national standard of testing for FMH immediately post delivery.

Ken DaVis – hEAD Of UNIT IMVS Transfusion Medicine

coLin sToRy – LABORATORy MANAGER Haematology

case RePoRT

Testing the cross match sample (collected two days after delivery) gave a weak result in the RhD group which was an unexpected finding. This was confirmed by further testing.

Consideration of this result and the fact that the maternal antibody screen failed to detect any trace of the RhD-Ig given two days earlier led the laboratory to recommend that an FMH screen be performed urgently, given that the 72 hour anti-D administration window was quickly closing. The cord Hb was reported as 118g/L (normal range 136-196g/L) which could be considered as a further marker to suspect a large FMH.

The FMH screen using both Kleihauer-Betke and flow cytometric techniques confirmed these findings with a result of greater than 3% foetal red cells.

formulae1 volume (mL) foetal RBC = % foetal RBC x 24 e.g. 3.19% x 24 = 77mL foetal RBC in this case2 anti-D dosage (6.25IU vial) = 1 vial per 6.25mL foetal RBC e.g. 77mL / 6.25mL = 12.3 vials as in this case

A 29 year old delivered an apparently non-anaemic RhD positive baby by caesarean section two days prior to a request for a crossmatch of two units of red cells for post partum anaemia. Her blood group was already known to be O RhD negative and she had already received the standard 625 IU RhD-Ig dose immediately after delivery.

Using the recommended formula it was estimated that an FMH of greater than 70mL had occurred.In discussion with her treating physician a further dose of 13 vials of WinRho RhD-Ig was recommended to be given intravenously. The FMH screen performed 48 hours later showed the anticipated full clearance of all fetal red cells and residual levels of anti-D in maternal circulation.

The RANZCOG ‘College Statement’ on anti-D administration is available at www.ranzcog.edu.au/womenshealth/anti-d.shtml.


Kleihauer-betke film with prominent numbers of rhd positive foetal cells

quality of life for the approximately 20% of patients with so called HER2 positive breast cancer. HER2 is also found in metastatic gastric cancer and hence herceptin can also be useful in treating it.

Recent advances in the power of DNA sequencing technologies, together with the discovery of genetic lesions in particular cancers, and the ability to specifically target those mutations with specialised drugs forms the basis of personalised medicine which will become the standard of patient care in the near future.

It is now possible to sequence an individual’s genome for a few thousand dollars. Equally importantly the protein coding genes that form the basis of personalised medicine can now be sequenced at the ACRF Cancer Genomics Facility for hundreds of dollars in just a few days.

The challenge now is to interpret this deluge of data and determine its relevance to human health, a challenge IMVS Pathology is proud to support. ¥

Key goals for researchers using the facility are to obtain insights into the genetic modifications that underpin cancer and to develop new tools for better diagnosis, prognosis, and treatment. Ultimately clinical translation will lead to greater personalisation and more effective cancer management.

CCB researchers recently won a $3.5 million grant from the Australian Cancer Research Foundation (ACRF), which together with support from the South Australian Government, the Cancer Council SA, the Federal Government (via Therapeutic Innovation Australia), Medvet Laboratories and the University of Adelaide enabled the facility to be established.

Traditionally cancers have been classified and subsequently treated based on where they occur, for example lung cancer; and their pathology, such as non-small cell lung cancer. Increasingly however, cancers are being classified and treated based not only on their location, but on their genetics.

Treatments are being specifically targeted to the genetic lesions that the cancers themselves contain. Herceptin for example can significantly prolong and improve

PRof HamisH scoTT

Professor angel lopez Co-director Centre for Cancer biology

Professor hamish Scott Joint director aCrf Cancer genomics facility

New SA genomics facilityIn late 2012 the ACRF Cancer Genomics Facility will open in IMVS Pathology’s Centre for Cancer Biology (CCB).

flow cytometry scan of results (%hbf/rhd) showing upper right hand quadrant positive cells (3.19%)

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hbf fITC-TB

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NEXT ISSUE In our next edition we will discuss further the guidelines for use of RhD immunoglobulin in pregnancy and the flow cytometry method used in this setting.

A follow-up maternal antibody screen was requested at six months post delivery to ensure that a sensitising event had not occurred.

For a haemorrhage greater than 6mL, the recommended dose is 100 IU per mL RhD positive red blood cells. Where large volumes of RhD-Ig need to be administered or the patient has a specific contra indication to intramuscular injections, an intravenous (IV) RhD-Ig preparation should be considered. ¥

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RESPIRATORy PAThOGENS

Since the start of 2012, IMVS Pathology has reported 2625 SA samples positive for influenza A and 105 for influenza B. Unlike the three previous years where influenza A(h1N1)pdm09 was the predominant strain, this season greater than 90% are h3N2 strains that are A/Victoria/361/2011-like. This is somewhat antigenically different to the A/Perth/16/2009 (h3N2)-like virus included in the Australian vaccine. however the influenza B strains in SA are closely related to the vaccine B/Brisbane/60/2008-like virus.

Several respiratory pathogens are co-circulating with influenza viruses. The table lists all respiratory viral activity (including Mycoplasma and Bordetella pertussis) in the week ending 29/7/2012 and year to date totals.


IMVS enquiries > Metropolitan 8222 3000 > Regional and Country 1800 188 077

Point of

Finger prick PoCT results are available within minutes. A referral is required however an appointment is not necessary. The test is reliable for patients undergoing anticoagulation therapy where their INR result is less than 3.5. However if the result is greater than 3.5, PoCT becomes less reliable and a citrated blood sample will automatically be taken and sent to the laboratory for confirmation. Medication changes should not be considered until the laboratory result is known. IMVS Pathology will telephone the result as soon as the analysis is complete.

INR results > 3.5PoCT INR results above 3.5 will generally be higher than that of a laboratory. A recent data review confirmed this observation with

25% of patients also demonstrating a variation of greater than 0.5 in the range 3.5 – 4.0. The cause of this variation in the high INR range is the different impact of low coagulation factor levels on the two systems. However both systems are indicating that a review of dose is required. Also, antiphospholipid antibodies such as anticardiolipin or lupus antibodies are known to falsely prolong coagulation times using PoCT systems.

Snake biteA recent alert indicated that Point of Care INR systems should not be used in the management of patients with suspected snake envenomation. Evidence suggests that a component in some species of snake venoms may directly affect the reliability of the INR testing process.

The documented cases involve brown snake venom, however, related or other species, may also exhibit a similar affect.

If snake bite is suspected a blood sample should be taken and referred to the laboratory for INR testing.

ConclusionPoCT is an accurate and reliable test for patients undergoing anticoagulation therapy where their INR result is less than 3.5. IMVS Pathology’s Point of Care test is fully NATA accredited and we participate in a range of quality control programs.

gRaeme BReTTig – MANAGER Point of Care Testing

IMVS Pathology has been progressively rolling out Point of Care Testing (PoCT) services since 2007.

Care Munno Para West UniHealth Playford GP Super Clinic

Elizabeth GP Plus Health Care Centre

Kadina

Gumeracha

Port Lincoln Lincoln Medical Centre

Barmera

Berri

Point of Care (finger prick) testing is now available at these additional Patient Centres:

Virus

Influenza A

Influenza A (Swine)

Influenza B

RSV

Parainfluenza 1

Parainfluenza 2

Parainfluenza 3

Adenovirus

Metapneumovirus

Rhinovirus

Myco Pneumoniae

B Pertussis

Total

328

0

12

143

7

4

17

16

43

175

2

3

750

year to date

2625

18

105

1163

339

36

100

380

268

3296

75

120

8525

WEEK ENDING 29/07/12

new patient centres coeliac disease - sa pathology

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