haemoglobin – o · haemoglobin •a protein molecule found in red blood cells. •delivers oxygen...
TRANSCRIPT
HAEMOGLOBIN
• A PROTEIN MOLECULE FOUND IN RED BLOOD CELLS.
• DELIVERS OXYGEN TO THE BODY’S TISSUES AND REMOVES
CARBON DIOXIDE VIA THE LUNGS.
• 2 ALPHA AND 2 BETA GLOBIN CHAINS EACH CONTAINING A
HAEM GROUP THAT CONTAINS AN IRON MOLECULE.
• REQUESTED BY A CLINICIAN AS PART OF A FULL BLOOD
COUNT AND IS USED IN THE INVESTIGATION OF ANAEMIA.
SYSMEX XN-1000• THE SYSMEX XN-1000 ANALYSER USES THE SLS-HB METHOD WHICH MEASURES HB USING
LIGHT ABSORBANCE.
• ALL CELLS ARE LYSED BY REAGENT.
• HYDROPHOBIC PORTION OF SLS CAUSES A
CONFORMATIONAL CHANGE TO EXPOSE THE HAEM
UNIT.
• FE2+ IS OXIDISED TO FE3+.
• HYDROPHILIC GROUP OF SLS BINDS FE3+ TO
FORM A STABLE COLOURED PRODUCT.
• THIS SLS-HB IS MEASURED PHOTOMETRICALLY.
• LIGHT ABSORBANCE IS PROPORTIONAL TO HB
CONCENTRATION.
LIPAEMIA
• CAUSES TURBIDITY IN THE LYSATE.
• FALSELY ELEVATES THE ABSORBANCE OVERESTIMATION OF HB
CONCENTRATION
• THE HB IS USED TO CALCULATE THE MCH (HB/RBC) AND MCHC (HB/HCT)
• RESULTS NEED TO BE CORRECTED.
PLASMA HB• DETECTION:
• FALSELY INCREASED HB RESULTS IN AN ELEVATED MCHC:
MCHC= HAEMOGLOBIN____
HAEMATOCRIT
•
MCHC >365 AND
Difference between the RBC-O and RBC-I is
<0.15
IT3000 Algorhyt
hm
“?Lipaemia” Flag
PLASMA HB• CORRECTION:
• PORTION OF SAMPLE IS CENTRIFUGED AND PLASMA SEPARATED INTO ANOTHER
TUBE
• PLASMA ANALYZED TO GIVE A PLASMA HB VALUE
• THIS IS USED TO CALCULATE A MORE ACCURATE HB VALUE.
• CORRECTED HB = HB – ((PLASMA HB X (1-HAEMATOCRIT))
• THE CORRECTED HB IS THEN USED TO RECALCULATE THE MCH AND MCHC.
• INEFFICIENT, LABOUR INTENSIVE AND LEAVES A LOT OF ROOM FOR ERROR.
• ~1 SAMPLE PER WEEK
• ~15- 20 MINUTES PER SAMPLE
WHY WE IT
1. DELAYS THE TRUE RESULT BEING SENT TO THE CLINICIAN, WHICH CAN DELAY TREATMENT.
2. THIS CAN ALSO DELAY OTHER SAMPLES FROM BEING ANALYSED AS THE ANALYSER IS TAKEN
OFFLINE TO RUN THE PLASMA MANUALLY (I.E. NO OTHER SAMPLES CAN RUN THROUGH)
3. OPENING A SAMPLE TUBE IS A HEALTH AND SAFETY RISK TO STAFF.
4. IF PIPETTING IS NOT DONE CAREFULLY, RED CELLS CAN BE TRANSFERRED ALONG WITH THE
PLASMA INTO THE NEW TUBE FOR REANALYZING. THIS WILL FALSELY INCREASE THE PLASMA
HB RESULT LEADING TO A FALSELY LOWERED FINAL HB.
5. A LARGE AMOUNT OF SAMPLE IS USED
a) INSUFFICIENT SAMPLE FOR FURTHER TESTS
b) CANNOT BE DONE ON PAEDIATRIC SAMPLES
OPTICAL HB (HB-O)
• RESEARCH PARAMETER ON THE XN20 ANALYSER.
• ANALYSED IN THE RET CHANNEL (I.E. THE PART OF
THE MACHINE THAT MEASURES THE
RETICULOCYTE COUNT)
• ANALYZES THE RED CELLS WHOLE, SINGLY AND
USING FLOW CYTOMETRY.
• CALCULATED FROM THE RBC-O AND RBC-HE (MCH
EQUIVALENT):
HB-O= RBC-O X RBC-HE
WHY WE IT1. NO INTERFERENCE BY LIPAEMIA AS CELLS ARE MEASURED INSTEAD OF A LYSATE.
2. SIMPLER METHOD WITH IMMEDIATE RESULT
3. CLOSED SYSTEM
4. THE CLINICIAN WOULD RECEIVE THE TRUE HB RESULT WITHIN A SHORTER TIME
FRAME
5. NO IMPACT ON THE TURNAROUND TIME FOR OTHER PATIENT SAMPLES
6. NO EXTRA SAMPLE AMOUNT IS REQUIRED (UNLESS THE RET CHANNEL WASN’T
UTILIZED ON FIRST RUN I.E. FOR RETICS)
HOW DOES IT COMPARE WITH THE PLASMA HB METHOD?. . . .
METHOD
• 31 SAMPLES WHICH FLAGGED FOR LIPAEMIA WERE CORRECTED USING THE PLASMA HB METHOD
• SOME SAMPLES WERE ANALYSED IN THE RET CHANNEL INITIALLY. I.E. RUN FOR RETICULOCYTES
• IF NOT, THE SAMPLES WERE RETRIEVED AND REANALYSED IN THE RET CHANNEL TO GIVE THE HB-O RESULT
• THE MCH, MCHC AND THEIR OPTICAL EQUIVALENTS (RBC-HE AND MCHC-O) WERE ALSO NOTED
• “NORMAL” SAMPLES (LIPAEMIA INDEX <10, MCHC <365) WERE ALSO OBTAINED TO COMPARE THE HB-O WITH THE REPORTED HB AND PROVE THAT THESE CAN BE INTERCHANGEABLE
RESULTSLIPAEMIC SAMPLES
• NUMBER OF SAMPLES: 31
• HB RANGED FROM:60-183 G/L
• LIPAEMIA INDEX RANGED FROM :62-3694
• % DIFFERENCE IN HB:0.0-6.9% (OUTLIER OF 16.9%)
• MEAN % DIFFERENCE:3.4%
NON-LIPAEMIC SAMPLES
• NUMBER OF SAMPLES: 31
• HB RANGED FROM:81-162 G/L
• LIPAEMIA INDEX RANGED FROM :1-10
• % DIFFERENCE IN HB:0.0-5.0%
• MEAN % DIFFERENCE:1.8%
MOU= 3.9%
OUTLIER• 14.03.2017
• HB=135
• CORRECTED HB=122 VS HB-O=103 (% DIFFERENCE 16.9%)
• HAEMOLYSIS 115, LIPAEMIA 1294 – WITHIN RANGE OF THE OTHER SAMPLES.
• CLINICALS – RENAL PATIENT
• 13.03.2017• CORRECTED HB= 103
• 15.03.2017• CORRECTED HB= 102
HUMAN ERROR WITH PLASMA HB METHOD?
RESULTS
y = 0.9804x + 1.4366R² = 0.9792
0
20
40
60
80
100
120
140
160
180
200
0 20 40 60 80 100 120 140 160 180 200
Hb
-O
Corrected Hb
Lipaemic Hb Comparisony = 1.0538x - 6.1806
R² = 0.9858
0
20
40
60
80
100
120
140
160
180
0 50 100 150 200
Hb
-O
Reported Hb
Non-Lipaemic Hb Comparison
THE HB-O CAN BE USED WHEN A SAMPLE IS LIPAEMIC,
INSTEAD OF USING THE PLASMA HB METHOD TO
CORRECT THE ORIGINAL HB RESULT.
TO NOTE - HAEMOLYSIS
• FLOW CYTOMETRY REQUIRES WHOLE CELLS TO ANALYSE.
• IN VITRO HAEMOLYSIS CAN BE CAUSED BY SOME PRE-ANALYTICAL
PROBLEMS SUCH AS DELAY, ROUGH TRANSPORT OR THERMAL IMPACT.
• THESE WILL LEAD TO RED CELL DESTRUCTION PROVIDING AN
UNDERESTIMATION OF HB-O.
• THE SLS-HB WITH PLASMA HB CORRECTION METHOD WILL NEED TO BE USED
IN SUCH CIRCUMSTANCES AS IT USES ABSORBANCE OF FREE HAEMOGLOBIN.
TO NOTE - HIGH WCC
• HB FALSELY ELEVATED WITH MARKEDLY HIGH WCC - LEADING TO AN
INCREASED MCHC AND MCH
• WE CANNOT REMOVE WHITE CELLS FROM A SAMPLE AND RUN IT AGAIN TO SEE
IF IT GIVES A RESULT THE SAME AS THE HB-O FROM THE ORIGINAL RUN
• NO WAY OF TESTING WHETHER THE HB-O IS ACCURATE OR NOT SO IT CANT BE
VALIDATED
TO NOTE - QUALITY CONTROL
• THE HB-O PARAMETER IS NOT MONITORED BY ANY EXTERNAL QUALITY
CONTROL AND IS NOT INCLUDED IN THE LIST OF TESTS ON SNCS.
PROPOSAL . . .
• THE HB-O RESULT CAN BE SENT THROUGH TO IT3K WITH THE REST OF THE FBC RESULTS WHEN THE "?LIPAEMIC" FLAG IS GENERATED
• ?"LIPAEMIA" IS A DROP DOWN BOX SO WHEN CLICKED ON CAN HAVE THE HB-O AS AN OPTION
• WHEN CHOSEN, THE HB RESULT WILL BE REPLACED WITH THE HB-O RESULT AND THE MCHC AND MCH REMOVED
• HB-O CAN BE USED TO CALCULATE THE NEW MCH AND MCHC
• AUTOMATIC COMMENT ATTACHED TO THE RESULTS STATING THAT THE OPTICAL HB IS REPORTED AND WAS USED TO CALCULATE THE MCH AND MCHC
REFERENCES
• SYSMEX XN 9000 OPERATOR TRAINING MANUAL. XN TRAINING MANUAL (PART
I), REVISION 1: OCTOBER 2012. ROCHE DIAGNOSTICS NZ LTD.
• WWW.ECLINPATH.COM/HAEMATOLOGY/TESTS/HEMOGLOBIN/
• BERDA-HADDAD Y, FAURE C, BOUBAYA M, ARPIN M, COINTE S, FRANKEL D, ET
AL. INCREASED MEAN CORPUSCULAR HAEMOGLOBIN CONCENTRATION:
ARTEFACT OR PATHOLOGICAL CONDITION?. INTERNATIONAL JOURNAL OF
LABORATORY HAEMATOLOGY 2017; 39: 32-41.