izben c. williams, md, mph lecturer. lecture - 4a biolocical assessment of patients with psychiatric...
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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
Laboratory Examinations
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
Laboratory Examinations
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)
Laboratory Examinations
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
Laboratory Examinations
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