BEHAVIORAL SCIENCE

IzBen C. Williams, MD, MPHLecturer

Lecture - 4a

BIOLOCICAL ASSESSMENT OF

PATIENTS WITH PSYCHIATRIC SYMPTOMS

Laboratory Examinations

OVERVIEW 1:With psychiatrists’ increasing use of

certain psychotropic medications (eg, lithium, antidepressants, anticonvulsants), there has been a growing awareness of the usefulness of monitoring blood levels of these medications and their metabolites to guide therapy and to minimize adverse reactions or other complications.

Laboratory Examinations

OVERVIEW 2:With the current illicit substance

abuse epidemic there is also increasing need for psychiatric clinicians to be able to detect those patients whose psychiatric conditions might be affected by drug abuse.

Laboratory Examinations

OVERVIEW 3:Laboratory tests are often therefore,

essential diagnostic resource to psychiatrists

At the same time it should be appreciated that indiscriminate ordering of tests…….Is costly May short-circuit traditional clinical

practice procedures and guidelines It can undermine patient-physician

relationship

Laboratory Examinations

OVERVIEW 4:The request for diagnostic tests by

should therefore derive from, and should be dictated by, findings in the:HistoryMSE and Review of systems Physical examination

Laboratory Examinations

OVERVIEW 5:.It should also be emphasized that

negative test results do not always constitute proof that organic disease is not present

Thus, test results should always be viewed as part of the larger clinical picture

Laboratory Examinations

Monitoring patients for complications of pharmacotherapy - examples:The mood stabilizer Carbamazapine and

the antipsychotic Clozaril may cause blood dyscrasias such as agranulocytosis

Mood stabilizers carbamazapine and valproic acid may cause abnormal LFTs

Laboratory Examinations

Monitoring patients for complications of pharmacotherapy – examples 2:Thyroid function and renal function tests

should be carried out for patients receiving the mood stabilizer Lithium as this drug can cause thyroid hypo or hyper activity

Because serum Lithium has a narrow therapeutic range this is additional reason for regularly monitoring its serum level

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Tests for Endocrine Function:Hypothyroidism can mimic depressionHyperthyroidism an mimic anxiety

Therefore it may be important to rule out thyroid disease as a differential for these disorders

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Other endocrine abnormalities:Reduced levels of gonadotropins are seen

in schizophreniaDepression may also present with

abnormalities in growth hormone and melatonin (pineal gland), and a reduced response to a challenge with thyrotropin-releasing hormone

Laboratory Examinations

Other endocrine abnormalities:As with thyroid disease, adrenal dysfunction

may be associated with a wide range of psychiatric disturbances (stress connection).

The adrenals, you will recall, produce:Catecholamines (eg epinephrine)Glucocorticoids, mineralocorticoids, and

adrenal androgens (precursors of sex hormones)

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Other endocrine abnormalities:Addison’s disease and Cushing’s

syndrome, two major adrenal disorders, may present with psychiatric symptoms because of the biogenic amines production and other metabolic derangements which accompany these disorders

Reduced levels of gonadotropins are also seen in schizophrenia

Laboratory Examinations

Dexamethasone suppression test (DST)-1:

Dexamethasone is a type of steroidal medicationIt has anti-inflamatory and immunosuppressive

effectsIt is 25 times more potent than cortisol in its

glucocorticoid effectThe DST measures whether

adrenocorticotropic hormone (ACTH) secretion by the pituitary can be suppressed

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Dexamethasone suppression test (DST)-2:In a person with normal hypothalamic-adrenal-

pituitary axis, dexamethasone suppresses the secretion of cortisol

In only 50% of persons with major depressive disorder will this suppression occur; in the other 50% it is limited or absent

Hence DST has limited clinical usefulness, as non suppression is also seen in other mental conditions including schizophrenia and dementia

Dexamethasone suppression

Laboratory Examinations

Dexamethasone suppression test (DST)-2:

Plasma cortisol detects abnormalities in cortical secretion from the adrenal gland.

In principle low plasma cortisol suggests Addison’s disease, elevated plasma cortisol suggests Cushing’s disease.

DST is typically used to diagnose Cushing’s. It is of some limited value in diagnosing depression.

Other diagnostic in PsychiatryIt cannot be over emphasized that:

Request for laboratory or other diagnostic tests should derive from the Hist, ROS & PE

Negative test results do not constitute proof that organic disease is not present

The range of tests may include:Anatomic (eg CT scan)Functional (eg EEG, DST)Diagnostic (eg VDRL)

Other diagnostic tests used in Psychiatry

Case # 1: Let us take the case of a patient presenting with Delirium- an acute confusional stateToxicology screen indicated (cultural bias)

Heavy metalsHallucinogensAtropine substancesStimulantsCNS depressantsAnxioliticsPain medication, etc

Other diagnostic tests used in Psychiatry

Case # 2: Let us take the case of a patient presenting with Dementia – decline in mental ability enough to interfere with daily lifeList of tests to be considered:Blood plasma or serum

valuesAntigen and antibody testsCXR EKG EEGCT scanMRILumbar puncturePositron emission tomography