Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Laboratory Tests and Diagnostic Procedures
Key Points
-
The mainstay of psychiatric diagnosis involves a thorough history, mental status examination, and focused physical examination; however, laboratory tests and diagnostic studies are important adjuncts.
-
Laboratory tests and diagnostic studies are especially useful in the diagnostic work-up of high-risk populations.
-
Laboratory tests provide a clinically useful tool to monitor levels of many psychotropic drugs by guiding medication titration, preventing toxicity, and checking for compliance.
-
Although neuroimaging alone rarely establishes a psychiatric diagnosis, contemporary modalities are powerful tools in both the clinical and research realms of modern psychiatry.
Overview
Modern-day psychiatrists have many tools to help make a diagnosis and to treat patients effectively. While the heart of psychiatric diagnosis remains a careful interview and mental status examination (MSE) (while paying close attention to physical findings), laboratory tests (including blood work, neuroimaging, and an electroencephalogram [EEG]) are important adjuncts. These modalities help reveal medical and neurological causes of psychiatric symptoms, as well as aid in monitoring the progression of certain diseases. They are often of particular benefit in populations (including the elderly, the chronically medically ill, substance users and abusers, and the indigent) at high risk for medical co-morbidity. Laboratory tests are also commonly used to check blood levels of psychotropic medications and to predict potential side effects. This chapter will focus on the role of a wide array of specific serum, urine, and cerebrospinal fluid (CSF) tests, as well as several diagnostic modalities (e.g., the EEG and neuroimaging), with an emphasis on the strategy and rationale for choosing when to order and how to use the data derived from particular studies. Genetic and biological markers will be discussed in subsequent chapters.
A General Approach to Choosing Laboratory Tests and Diagnostic Studies
Diagnoses in psychiatry are primarily made by the identification of symptom patterns, that is, by clinical phenomenology, as outlined in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). In this light, the initial approach to psychiatric assessment consists of a thorough history, a comprehensive MSE, and a focused physical examination. Results in each of these arenas guide further testing. For example, historical data and a review of systems may reveal evidence of medical conditions, substance abuse, or a family history of heritable conditions (e.g., Huntington's disease)—each of these considerations would lead down a distinct pathway of diagnostic evaluation. An MSE that uncovers new-onset psychosis or delirium opens up a broad differential diagnosis and numerous possible diagnostic studies from which to choose. Findings from a physical examination may provide key information that suggests a specific underlying pathophysiological mechanism and helps hone testing choices. Although routine screening for new-onset psychiatric illness is often done, consensus is lacking on which studies should be included in a screening battery. In current clinical practice, tests are ordered selectively with specific clinical situations steering this choice. While information obtained in the history, the physical examination, and the MSE is always the starting point, subsequent sections in this chapter address tests involved in the diagnostic evaluation of specific presentations in further detail.
Routine Screening
Decisions regarding routine screening for new-onset psychiatric illness involve consideration of the ease of administration, the clinical implications of abnormal results, the sensitivity and specificity, and the cost of tests. Certain presentations (such as age of onset after age 40 years, a history of chronic medical illness, or the sudden onset or rapid progression of symptoms) are especially suggestive of a medical cause of psychiatric symptoms and should prompt administration of a screening battery of tests. In clinical practice, these tests often include the complete blood cell count (CBC); serum chemistries; urine and blood toxicology; levels of vitamin B 12 , folate, and thyroid-stimulating hormone (TSH); and rapid plasma reagent (RPR). Liver function tests (LFTs), urinalysis, and chest x-ray are often obtained, especially in patients at high risk for dysfunction in these organ systems or in the elderly. A pregnancy test is important in women of childbearing age, from both a diagnostic and treatment-guidance standpoint. Box 3-1 outlines the commonly used screening battery for new-onset psychiatric symptoms. The following sections will move from routine screening to a more tailored approach of choosing a diagnostic work-up that is based on specific signs and symptoms and a plausible differential diagnosis.
Box 3-1
Commonly-Used Screening Battery for New-Onset Psychiatric Symptoms
Screening Tests
-
Complete blood count (CBC)
-
Serum chemistry panel
-
Thyroid-stimulating hormone (TSH)
-
Vitamin B 12 level
-
Folate level
-
Syphilis serologies (e.g., rapid plasma reagent [RPR], Venereal Disease Research Laboratories [VDRL])
-
Toxicology (urine and serum)
-
Urine or serum β-human chorionic gonadotropin (in women of childbearing age)
-
Liver function tests (LFTs)
Psychosis and Delirium
New-onset psychosis or delirium merits a broad and systematic medical and neurological work-up. Table 3-1 outlines the wide array of potential medical causes of such psychiatric symptoms. Some etiologies include infections (both systemic and in the central nervous system [CNS]), CNS lesions (e.g., stroke, traumatic bleed, or tumors), metabolic abnormalities, medication effects, intoxication or states of withdrawal, states of low perfusion or low oxygenation, seizures, and autoimmune illnesses. Given the potential morbidity (if not mortality) associated with many of these conditions, prompt diagnosis is essential. A comprehensive, yet efficient and tailored approach to a differential diagnosis involves starting with a thorough history supplemented by both the physical examination and MSE. Particular attention should be paid to vital signs and examination of the neurological and cardiac systems. Table 3-2 provides an overview of selected physical findings associated with psychiatric symptoms. Based on the presence of such findings, the clinician then chooses appropriate follow-up studies to help confirm or refute the possible diagnoses. For example, tachycardia in the setting of a goiter suggests possible hyperthyroidism and prompts assessment of thyroid studies ( Figure 3-1 ). On the other hand, tachycardia with diaphoresis, tremor, and palmar erythema, along with spider nevi, is suggestive of both alcohol withdrawal and stigmata of cirrhosis from chronic alcohol use ( Figure 3-2 ). The astute clinician would treat for alcohol withdrawal and order laboratory tests (including LFTs, prothrombin time [PT]/international normalized ratio [INR], and possible abdominal imaging), in addition to the screening tests already outlined in Box 3-1 . Neuroimaging is indicated in the event of neurological findings, although many would suggest that brain imaging is prudent in any case of new-onset psychosis or acute mental status change (without a clear cause). An EEG may help to diagnose seizures or provide a further clue to the diagnosis of a toxic or metabolic encephalopathy. A lumbar puncture (LP) is indicated (after ruling-out an intracranial lesion or increased intracerebral pressure) in a patient who has fever, headache, photophobia, or meningeal symptoms. Depending on the clinical circumstances, routine CSF studies (e.g., the appearance, opening pressure, cell counts, levels of protein and glucose, culture results, and a Gram stain), as well as specialized markers (e.g., antigens for herpes simplex virus, cryptococcus, and Lyme disease; a cytological examination for malignancy; and acid-fast staining for tuberculosis), should be ordered. A history of risky sexual behavior or of intravenous (IV) or intranasal drug use makes testing for infection with the human immunodeficiency virus (HIV) and hepatitis C especially important. Based on clinical suspicion, other tests might include an antinuclear antibody (ANA) and an erythrocyte sedimentation rate (ESR) for autoimmune diseases (e.g., systemic lupus erythematosus [SLE], rheumatoid arthritis [RA]), ceruloplasmin (that is decreased in Wilson's disease), and levels of serum heavy metals (e.g., mercury, lead, arsenic, and manganese). Box 3-2 provides an initial approach to the diagnostic work-up of psychosis and delirium. Specific studies will be further discussed based on an organ-system approach to follow.
TABLE 3-1
Medical and Neurological Causes for Psychiatric Symptoms
Adapted from Roffman JL, Silverman BC, Stern TA. Diagnostic rating scales and laboratory tests. In Stern TA, Fricchione GL, Cassem NH et al, editors: Massachusetts General Hospital handbook of general hospital psychiatry, ed 6, Philadelphia, 2010, Saunders Elsevier.
| Metabolic | Hypernatremia/hyponatremia |
| Hypercalcemia/hypocalcemia | |
| Hyperglycemia/hypoglycemia | |
| Ketoacidosis | |
| Uremic encephalopathy | |
| Hepatic encephalopathy | |
| Hypoxemia | |
| Deficiency states (vitamin B 12 , folate, and thiamine) | |
| Acute intermittent porphyria | |
| Endocrine | Hyperthyroidism/hypothyroidism |
| Hyperparathyroidism/hypoparathyroidism | |
| Adrenal insufficiency (primary or secondary) | |
| Hypercortisolism | |
| Pituitary adenoma | |
| Panhypopituitarism | |
| Pheochromocytoma | |
| Infectious | HIV/AIDS |
| Meningitis | |
| Encephalitis | |
| Brain abscess | |
| Sepsis | |
| Urinary tract infection | |
| Lyme disease | |
| Neurosyphilis | |
| Tuberculosis | |
| Intoxication/withdrawal | Acute or chronic drug or alcohol intoxication/ withdrawal |
| Medications (side effects, toxic levels, interactions) | |
| Heavy metals (lead, mercury, arsenic, manganese) | |
| Environmental toxins (e.g., carbon monoxide) | |
| Autoimmune | Systemic lupus erythematosus |
| Rheumatoid arthritis | |
| Vascular | Vasculitis |
| Cerebrovascular accident | |
| Multi-infarct dementia | |
| Hypertensive encephalopathy | |
| Neoplastic | Central nervous system tumors |
| Paraneoplastic syndromes | |
| Pancreatic and endocrine tumors | |
| Epilepsy | Post-ictal or intra-ictal states |
| Complex partial seizures | |
| Structural | Normal pressure hydrocephalus |
| Degenerative | Alzheimer's disease |
| Parkinson's disease | |
| Pick's disease | |
| Huntington's disease | |
| Wilson's disease | |
| Demyelinating | Multiple sclerosis |
| Traumatic | Intracranial haemorrhage |
| Traumatic brain injury |
AIDS, Acquired immunodeficiency syndrome; HIV, human immunodeficiency virus.
TABLE 3-2
Selected Findings on the Physical Examination Associated with Neuropsychiatric Manifestations
Adapted from Smith FA, Querques J, Levenson JL, Stern TA. Psychiatric assessment and consultation. In Levenson JL, editor: The American Psychiatric Publishing textbook of psychosomatic medicine, Washington, DC, 2005, American Psychiatric Publishing.
| Elements | Possible Examples |
|---|---|
| G eneral A ppearance | |
| Body habitus—thin | Eating disorders, nutritional deficiency states, cachexia of chronic illness |
| Body habitus—obese | Eating disorders, obstructive sleep apnea, metabolic syndrome (neuroleptic side effect) |
| V ital S igns | |
| Fever | Infection or neuroleptic malignant syndrome (NMS) |
| Blood pressure or pulse abnormalities | Cardiovascular or cerebral perfusion dysfunction; intoxication or withdrawal states, thyroid disease |
| Tachypnea/low oxygen saturation | Hypoxemia |
| S kin | |
| Diaphoresis | Fever; alcohol, opiate, or benzodiazepine withdrawal |
| Dry, flushed | Anticholinergic toxicity |
| Pallor | Anemia |
| Unkempt hair or fingernails | Poor self-care or malnutrition |
| Scars | Previous trauma or self-injury |
| Track marks/abscesses | Intravenous drug use |
| Characteristic stigmata | Syphilis, cirrhosis, or self-mutilation |
| Bruises | Physical abuse, ataxia, traumatic brain injury |
| Cherry red skin and mucous membranes | Carbon monoxide poisoning |
| Goiter | Thyroid disease |
| E yes | |
| Mydriasis | Opiate withdrawal, anticholinergic toxicity |
| Miosis | Opiate intoxication |
| Kayser–Fleischer pupillary rings | Wilson's disease |
| N eurological | |
| Tremors, agitation, myoclonus | Delirium, withdrawal syndromes, parkinsonism |
| Presence of primitive reflexes (e.g., snout, glabellar, and grasp) | Dementia, frontal lobe dysfunction |
| Hyperactive deep-tendon reflexes | Alcohol or benzodiazepine withdrawal, delirium |
| Ophthalmoplegia | Wernicke's encephalopathy, brainstem dysfunction, dystonic reaction |
| Papilledema | Increased intracranial pressure |
| Hypertonia, rigidity, catatonia, parkinsonism | Extrapyramidal symptoms (EPS) of antipsychotics, NMS, organic causes of catatonia |
| Abnormal movements | Parkinson's disease, Huntington's disease, EPS |
| Gait disturbance | Normal pressure hydrocephalus, Huntington's disease, Parkinson's disease |
| Loss of position and vibratory sense | Vitamin B 12 or thiamine deficiency |
| Kernig or Brudzinski sign | Meningitis |
Box 3-2
Adapted from Smith FA. An approach to the use of laboratory tests. In Stern TA, editor: The ten-minute guide to psychiatric diagnosis and treatment, New York, 2005, Professional Publishing Group, Ltd, p 318.
Approach to the Evaluation of Psychosis and Delirium
Screening Tests
-
Complete blood count (CBC)
-
Serum chemistry panel
-
Thyroid-stimulating hormone (TSH)
-
Vitamin B 12 level
-
Folate level
-
Syphilis serologies
-
Toxicology (urine and serum)
-
Urine or serum β-human chorionic gonadotropin (in women of childbearing age)
Further Laboratory Tests Based on Clinical Suspicion
-
Liver function tests
-
Calcium
-
Phosphorus
-
Magnesium
-
Ammonia
-
Ceruloplasmin
-
Urinalysis
-
Blood or urine cultures
-
Human immunodeficiency virus (HIV) test
-
Erythrocyte sedimentation rate (ESR)
-
Serum heavy metals
-
Paraneoplastic studies
Other Diagnostic Studies Based on Clinical Suspicion
-
Lumbar puncture (cell count, appearance, opening pressure, Gram stain, culture, specialized markers)
-
Electroencephalogram (EEG)
-
Electrocardiogram (ECG)
-
Chest x-ray
-
Arterial blood gas
Neuroimaging
-
Computed tomography (CT)
-
Magnetic resonance imaging (MRI)
-
Positron emission tomography (PET)
Anxiety Disorders
Medical conditions associated with new-onset anxiety are associated with a host of organ systems. For anxiety, as with other psychiatric symptoms, a late onset, a precipitous course, atypical symptoms, or a history of chronic medical illness raises the suspicion of a medical rather than a primary psychiatric etiology. Table 3-3 lists many of the potential medical etiologies for anxiety. These include cardiac disease (including myocardial infarction [MI] and mitral valve prolapse [MVP]); respiratory compromise (e.g., chronic obstructive pulmonary disease [COPD], asthma exacerbation, pulmonary embolism, pneumonia, and obstructive sleep apnea [OSA]); endocrine dysfunction (e.g., of the thyroid or parathyroid); neurological disorders (e.g., seizures or brain injury); or use or abuse of drugs and other substances. Less common causes (e.g., pheochromocytoma, acute intermittent porphyria, and hyperadrenalism) should be investigated if warranted by the clinical presentation. See Table 3-3 for the appropriate laboratory and diagnostic tests associated with each of these diagnoses.
TABLE 3-3
Medical Etiologies of Anxiety with Diagnostic Tests
Adapted from Smith FA. An approach to the use of laboratory tests. In Stern TA, editor: The ten-minute guide to psychiatric diagnosis and treatment, New York, 2005, Professional Publishing Group, Ltd, p 319.
| Condition | Screening Test |
|---|---|
| M etabolic | |
| Hypoglycemia | Serum glucose |
| E ndocrine | |
| Thyroid dysfunction | Thyroid function tests |
| Parathyroid dysfunction | PTH, ionized calcium |
| Menopause | Estrogen, FSH |
| Hyperadrenalism | Dexamethasone suppression test or 24-hour urine cortisol |
| I ntoxication /W ithdrawal S tates | |
| Alcohol, drugs, medications | Urine/serum toxicology |
| Vital signs | |
| Specific drug levels | |
| Environmental toxins | Heavy metal screen |
| Carbon monoxide level | |
| A utoimmune | |
| Porphyria | Urine porphyrins |
| Pheochromocytoma | Urine vanillylmandelic acid (VMA) |
| C ardiac | |
| Myocardial infarction | ECG, troponin, CK-MB |
| Mitral valve prolapse | Cardiac ultrasound |
| P ulmonary | |
| COPD, asthma, pneumonia | Pulse oximetry, chest x-ray, pulmonary function tests |
| Sleep apnea | Pulse oximetry, polysomnography |
| Pulmonary embolism | D-dimer, V/Q scan, CT scan of chest |
| E pilepsy | |
| Seizure | EEG |
| T rauma | |
| Intracranial bleed, traumatic brain injury | CT, MRI of brain |
| Neuropsychiatric testing | |
CK-MB, Creatine phosphokinase-MB band; COPD, chronic obstructive pulmonary disease; CT, computed tomography; ECG, electrocardiogram; EEG, electroencephalogram; FSH, follicle-stimulating hormone; MRI, magnetic resonance imaging; PTH, parathyroid hormone; V/Q, ventilation/perfusion.
Mood Disorders
While depression may be a primary psychiatric disorder, it is also associated with medical conditions. Clinical findings suggestive of thyroid dysfunction, Addison's disease or Cushing's disease, pituitary adenoma, neurodegenerative disorders, SLE, anemia, or pancreatic cancer should guide further testing. Work-up of these conditions is described below. The new onset of mania merits a full medical and neurological evaluation on a par with that of psychosis and delirium as previously described. While not every diagnostic test and its potential manifestation are discussed here, the following sections provide a more comprehensive system-driven approach to such a diagnostic work-up.
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here