Psychiatry- Diagnostics in Psychiatry

• Two recent issues have pushed medical assessment and laboratory

  testing in psychiatric patients:

  • widespread recognition of the pervasive problem of metabolic syndrome in clinical psychiatry
  • shorter life expectancy of psychiatric patients compared with that of the general population
• The history guides the clinician in the selection of laboratory studies that are relevant for a specific patient.
• Laboratory tests can be used to confirm or exclude diagnoses, monitor treatment response, assess prognosis, identify complications, and screen for comorbid conditions.
• Social history – character of pathology, including risk factors for personality disorders; also includes a legal history, information about family and other significant relationships, and an occupational history
• “demented” – the role of P.E. is to elucidate possible causative factors

  such as the cogwheel rigidity and tremor associated with Parkinson

  disease or neurologic deficits suggestive of prior stroke.
• Standard Laboratory Studies

  CBC

  serum electrolytes

  liver function tests (LFTs)

  blood urea nitrogen (BUN)

  creatinine (Cr)

  thyroid functions test

  serum B12 & folate levels

  VDRL test

  urinalysis
• • Often a CT scan is performed if there are focal neurologic findings
• electroencephalogram (EEG) may be performed if there is delirium.
• Imaging of the Central Nervous System

  • Structural – provides a detailed, noninvasive visualization of the

  morphology of the brain
• Structural – provides a detailed, noninvasive visualization of the

  morphology of the brain

  • e.g. x-ray, CT, and magnetic resonance imaging (MRI)
• Functional Imaging – provides information about the physiologic activity of the brain
• • Functional – provides a visualization of the spatial distribution of specific

  biochemical processes

  e.g. PET, single-photon emission computed tomography

  (SPECT), fMRI, and magnetic resonance spectroscopy (MRS)

  • research tools that are not yet ready for routine clinical use
• MRI

  • used to distinguish structural brain abnormalities that may be

  associated with a patient’s behavioral changes

  • provide the clinician with images of anatomical structures viewed from cross-sectional, coronal, or obliques perspectives
• MRI= - particularly useful in examining the temporal lobes, the cerebellum and the deep subcortical structures

  • particular diseases: nonmeningeal neoplasms, vascular

  malformations, seizure foci, demyelinating disorders,

  neurodegenerative disorders, and infarctions
• CT

  it provides the clinician with cross-sectional x-ray images of the

  brain

  • looking for evidence of a stroke, subdural hematoma, tumor, or

  abscess; skull fractures; meningeal tumor, calcified lesions, acute

  subarachnoid or parenchymal hemorrhage; acute parenchymal

  infarction
• contrast: enhance visualization of diseases that alter the blood-

  brain barrier such as tumors, strokes, abscesses, and other infections
• PET

  • involves the detection & measurement of emitted positron

  radiation after the injection of a compound that has been tagged

  with a positron-emitting isotope
• PET typically use fluorodeoxyglucose (FDG) to measure regional brain

  glucose metabolism
• Alzheimer type dementia: pattern of temporo-parietal glucose

  hypometabolism in patients with Alzheimer type dementia
• pet scanning using FDDNP: differentiates between normal aging,

  mild cognitive impairment, and Alzheimer disease
• • fMRI

  research scan used to measure regional cerebral blood flow

  • measurement of blood flow involves the use of heme molecule as an endogenous contrast agent; the rate of flow of heme molecules can be measured, resulting in an assessment of regional cerebral metabolism
• Urine drugs of abuse screens are immunoassays that detect barbiturates, benzodiazepines, cocaine metabolites, opiates, phencyclidine, tetrahydrocannabinol, and tricyclic antidepressants
• Testing for drugs of abuse is usually performed on urine specimens; it

  also may be performed on specimens of blood, breath (alcohol), hair,

  saliva, and sweat
• Urine screens provide information about the recent use of frequently

  abused drugs
• Increase in mean corpuscular volume : alcohol use disorder
• Increased liver enzymes : alcohol use disorder or from hepatitis B or C acquired from intravenous (IV) drug abuse
• IV drug abusers : risk for bacterial endocarditis
• Alcohol can still br detected in urine after 7-12 hours
• cocaine can still br detected in urine after 6-8 hours
• cocaine metabolite can still br detected in urine after 2-4 days
• short actingbarbiturates can still br detected in urine after 24 hours
• Marijuana can still br detected in urine after 2-7 days
• Morphine can still br detected in urine after 48-72 hours
• No single test or finding on P.E. is diagnostic for alcohol use disorder
• A high BAL in a patient who clinically does not show significant

  intoxication is consistent with tolerance
• In patients with acute alcohol intoxication, a blood alcohol level (BAL)

  may be useful
• Significant clinical evidence of intoxication with a low BAL should

  suggest intoxication with additional agents
• Intoxication is commonly found with levels between 100 and 300 mg/dL
• Chronic alcohol use:

  increased liver enzymes (AST > ALT)

  elevated bilirubin

  total protein and albumin may be low

  prothrombin may be increased

  • macrocytic anemia may be present
• In withdrawal, patients may have hypertension, tremulousness, and

  tachycardia