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112 Laboratory Medicine in Psychiatry and Behavioral Science
Electroencephalogram (EEG) (continued)
Fauci AS, Braunwald E, Kasper DL, et al (eds): Harrison’s Principles of Internal Medicine, 17th Edition.
New York, McGraw-Hill, 2008
Fernandes ML, Oliveira WM, Santos MV, Gomez RS: Sedation for electroencephalography with dex-
medetomidine or chloral hydrate: a comparative study on the qualitative and quantitative electroen-
cephalogram pattern. J Neurosurg Anesthesiol 27(1):21–25, 2015
Jacobson S, Jerrier H: EEG in delirium. Semin Clin Neuropsychiatry 5:86–92, 2000
https://t.me/med1917
113 Laboratory Tests
Electrolytes panel
Type of test Blood
Background and explanation
of test
This panel includes the following four tests:
• Sodium
• Potassium
• Chloride
• Carbon dioxide
Relevance to psychiatry and
behavioral science
This panel is used to screen and monitor for basic electrolyte
abnormalities in patients considering treatment with lith
-
ium and certain other psychotropic drugs.
Preparation of patient None needed
Indications •
Detecting or ruling out a specific lab abnormality
• Monitoring a known condition and its associated lab ab-
normality
Reference range See entries for individual tests.
Critical value(s) See entries for individual tests.
Increased levels See entries for individual tests.
Decreased levels See entries for individual tests.
Interfering factors See entries for individual tests.
Cross-references Basic Metabolic Panel
Comprehensive Metabolic Panel
See entries for individual tests.
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114 Laboratory Medicine in Psychiatry and Behavioral Science
Electromyography (EMG) and nerve conduction testing (NCT)
Type of test Neurophysiology
Background and explanation
of test
An EMG evaluates the electrical activity of muscles, and
NCT evaluates the activity of nerves. In an EMG, needles are
inserted into muscle tissue, and electrodes are attached to
the skin. Recordings are made at rest and with voluntary
muscle contraction. In NCT, electric current is applied to the
nerve so the velocity of nerve transmission can be measured
for either motor or sensory nerves. Neurological conditions
with abnormal test results are listed below.
Relevance to psychiatry and
behavioral science
The primary use of electromyography in psychiatric prac-
tice relates to the workup of functional neurological symp-
tom disorders, for which normal test results aid in excluding
muscle or nerve pathology as a cause of symptoms such as
weakness or paralysis.
Preparation of patient Patients should be instructed to bathe or shower, avoid ap-
plication of deodorants and cosmetics (including powders
and lotions), and avoid caffeine and tobacco prior to testing.
An EMG takes 30–60 minutes.
Indications • Neuromuscular disease
• Primary myopathy
• Neuropathy
Reference range EMG: No electrical activity at rest
NCT: Nerve conduction velocities range from 40 ms to
70 ms, varying with particular nerve studied.
Critical value(s) None
Abnormal test • Peripheral neuropathy
• Carpal tunnel syndrome
• Muscular dystrophy and other myopathies
• Guillain-Barré syndrome
• Myositis
Interfering factors Drugs affecting neuromuscular conduction
Poor patient cooperation
Cross-references Peripheral Neuropathy
Chemali KR, Tsao B: Electrodiagnostic testing of nerves and muscles: when, why, and how to order. Cleve
Clin J Med 72:37–48, 2005
Daube JR: Clinical Neurophysiology. Philadelphia, PA, FA Davis, 1996
https://t.me/med1917
115 Laboratory Tests
Erythrocyte sedimentation rate (ESR)
Type of test Blood
Background and explanation
of test
The ESR is a measure of how rapidly RBCs settle out of an-
ticoagulated blood. The sample is placed in a narrow verti-
cal tube, and after 1 hour, the height of the clear supernatant
is measured. The ESR of normal blood is low because RBCs
do not normally aggregate. In the presence of infectious or
inflammatory processes, blood proteins are altered such
that RBCs become heavier and settle faster, so the measured
supernatant value is larger. In general, the ESR is correlated
with the plasma fibrinogen level.
The ESR has been widely used in the diagnosis of inflamma-
tory, infectious, and autoimmune diseases. It is sensitive
and inexpensive and thus remains a screening test of choice.
It is not specific to any particular disease process, so positive
results are followed up with other tests. It should not be
used to screen asymptomatic patients for disease.
Several laboratory methods are used to measure ESR, the
Westergren method being the standard. Automated meth-
ods are now common. In recent years, CRP has been increas-
ingly used in preference to the ESR for many indications
because the CRP more closely parallels the inflammatory
state. At present, the cost difference between the two tests is
minimal.
Relevance to psychiatry and
behavioral science
The ESR has been used in the diagnostic workup for pa-
tients with unexplained mental status changes, including
delirium. In geriatrics, it has been the blood test of choice
when temporal arteritis is among the diagnostic consider
-
ations. The ESR is elevated in SLE and heavy metal poison-
ing and in response to several psychotropic drugs as noted
below.
Preparation of patient None needed
Indications •
Diagnosing temporal arteritis and polymyalgia rheu-
matica
•
Monitoring the course and treatment of temporal arteri-
tis, polymyalgia rheumatica, and rheumatoid arthritis
• Evaluating patients with suspected inflammatory, infec-
tious, or neoplastic disease when the diagnosis cannot
be made by other means
•
Monitoring the course of chronic inflammatory diseases
• Assessing elderly patients who have vague symptoms
and nonspecific exam findings
Note: ESR may be normal in patients with cancer, infection,
or connective tissue disease.
Reference range Adult males: 0–15 mm/hour (>50 years, 0–20 mm/hour)
Adult females: 0–20 mm/hour (>50 years, 0–30 mm/hour)
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116 Laboratory Medicine in Psychiatry and Behavioral Science
Erythrocyte sedimentation rate (ESR) (continued)
Critical value(s) Extreme ESR elevations may be seen with malignant lym-
phocarcinoma of colon or breast, rheumatoid arthritis, or
myeloma.
Increased levels • Temporal arteritis
• Polymyalgia rheumatica
• SLE
• Infection
• Inflammatory disease
• Acute heavy metal poisoning
• Tissue destruction (e.g., MI)
• Malignant neoplasm
• Macroglobulinemia
• Multiple myeloma
• Anemia (acute or chronic disease)
• Late pregnancy, eclampsia
• Hypothyroidism or hyperthyroidism
Decreased levels Certain medications, as noted below
Interfering factors Some elderly females have ESR elevations up to 60 mm/
hour in the absence of disease. In younger females, menstru
-
ation and pregnancy can cause ESR elevations.
Other factors associated with increased ESR include ane-
mia, macrocytosis, and elevated blood levels of cholesterol,
fibrinogen, or globulins.
Certain drugs tend to increase ESR, including carbamaze-
pine and other anticonvulsants, clozapine, isotretinoin, oral
contraceptives, misoprostol, sulfamethoxazole, and zol
-
pidem.
Other drugs tend to decrease ESR, including corticotropin,
cortisone, prednisone, hydroxychloroquine, methotrexate,
NSAIDs, quinine, sulfasalazine, and trimethoprim.
Cross-references C-Reactive Protein
Systemic Lupus Erythematosus
American Association for Clinical Chemistry: Testing.com. Available at: https://www.testing.com. Ac-
cessed June 2021.
Fischbach FT, Fischbach MA: A Manual of Laboratory and Diagnostic Tests, 10th Edition. Philadelphia,
PA, Wolters Kluwer Health/Lippincott Williams and Wilkins, 2018
https://t.me/med1917
117 Laboratory Tests
Estrogens
Type of test Blood
Background and explanation
of test
The estrogens are hormones that regulate the development
of female sex organs and secondary sex characteristics. Total
estrogen measurement has largely been replaced by specific
hormone assays. The three most important estrogen frac
-
tions are estrone (E1), estradiol (E2), and estriol (E3). Estra-
diol is the most active of the estrogens and the most often
tested. In females, estradiol is produced mainly in the ova
-
ries and is responsible for ovulation, conception, and preg-
nancy. It also regulates cholesterol levels and promotes bone
health. Estriol is the estrogen of pregnancy, produced in the
placenta. Estrone is the major estrogen present after meno
-
pause, derived from adrenal gland metabolites and pro-
duced in adipose tissue.
Relevance to psychiatry and
behavioral science
Reduced estradiol levels with menopause may be associated
with low energy, fatigue, insomnia, and depression. When
these symptoms are present in a female age 45 years or older
with a history of typical symptoms of menopause, it is not
necessary to measure estradiol levels. Specific indications
for hormone measurement are listed below. In psychiatry,
estradiol may be measured in cases of precocious puberty,
female characteristics developing in a male, individuals un
-
dergoing male-to-female transition, or amenorrhea in the
context of anorexia nervosa.
Preparation of patient None needed
Indications Estradiol
• Abnormal or heavy menstrual bleeding
• Unexplained abnormal menstrual cycles (e.g., amenor-
rhea)
• Symptoms of menopause in female <45 years of age
• Infertility workup
• Early development of sex organs in a female
• Female characteristics in a male (e.g., gynecomastia)
• Evaluating ovarian estrogen-producing tumors in non-
menstruating females
• Monitoring hormone replacement therapy after meno-
pause
• Monitoring feminizing hormone therapy
Estriol: Evaluating fetal-placental
status in early pregnancy
Reference range Estradiol
For menstruating females, dependent on menstrual phase:
• Midfollicular: 24–114 pg/mL
• Midluteal: 80–273 pg/mL
• Periovulatory: 62–534 pg/mL
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118 Laboratory Medicine in Psychiatry and Behavioral Science
Estrogens (continued)
Reference range (continued) Postmenopausal females: 20–88 pg/mL
Females taking oral contraceptives: 12–50 pg/mL
Adult males: 20–75 pg/mL
Feminizing hormone therapy: maintain estradiol level
<200 pg/mL (and testosterone level <50 ng/dL)
Estriol: dependent on duration of pregnancy, time of day (di-
urnal variation)
Critical value(s) None
Increased levels Estradiol: precocious puberty, cirrhosis, gynecomastia in
males, hyperthyroidism, Klinefelter’s syndrome, polycystic
ovary syndrome, and tumors of the adrenal glands, ovary,
or testes
Estriol: precocious puberty, cirrhosis, multiple pregnancy,
feminizing tumors
Decreased levels Estradiol: amenorrhea, anorexia nervosa, extreme exercise,
hypopituitarism, menopause, infertility, osteoporosis, hy-
pogonadism, Turner syndrome
Estriol: failing pregnancy, increased risk of various fetal ab-
normalities
Interfering factors Diurnal variation, menstrual cycle variation, hypertension,
anemia, and liver or kidney dysfunction
Certain drugs tend to increase estrogen levels: steroids, am-
picillin, phenothiazines, tetracyclines, hydrochlorothiazide,
prochlorperazine, cascara sagrada (stimulant laxative), and
estrogen-containing drugs.
Clomiphene may decrease estrogen levels.
Cross-references Anorexia Nervosa
Cirrhosis
Klinefelter’s Syndrome
Thyrotoxicosis
American Association for Clinical Chemistry: Testing.com. Available at: https://www.testing.com. Ac-
cessed June 2021.
Fauci AS, Braunwald E, Kasper DL, et al (eds): Harrison’s Principles of Internal Medicine, 17th Edition.
New York, McGraw-Hill, 2008
Fischbach FT, Fischbach MA: A Manual of Laboratory and Diagnostic Tests, 10th Edition. Philadelphia,
PA, Wolters Kluwer Health/Lippincott Williams and Wilkins, 2018
Klein DA, Paradise SL, Goodwin ET: Caring for transgender and gender-diverse persons: what clinicians
should know. Am Fam Physician 98(11):645–653, 2018
Wu AHB: Tietz Clinical Guide to Laboratory Tests, 4th Edition. St. Louis, MO, WB Saunders, 2006
https://t.me/med1917
119 Laboratory Tests
Ethylene glycol level
Type of test Blood
Background and explanation
of test
Ethylene glycol is an odorless, sweet-tasting substance
found in certain detergents, paints, de-icing products, brake
fluid, and antifreeze. Ingestion of as little as 4 fl oz of eth
-
ylene glycol can be fatal for an average-sized adult. Eth-
ylene glycol can be accidentally ingested by children,
intentionally taken in overdose, or abused as a substance in
place of ethanol. Symptoms of toxicity include drunken
-
ness, CNS depression, metabolic acidosis, hypocalcemia,
and kidney injury. An elevated osmolal gap may be seen.
The diagnosis of ethylene glycol poisoning can be con-
firmed by the ethylene glycol level, although this test is not
available in all settings.
Relevance to psychiatry and
behavioral science
Alcoholic patients without access to ethanol sometimes
abuse ethylene glycol. Initial symptoms of ethylene glycol
poisoning resemble those of alcohol intoxication, except
that the patient’s breath does not smell like alcohol.
Preparation of patient None needed
Indications Clinical suspicion of ethylene glycol ingestion
Reference range Assay will not detect level <5 mg/dL.
Critical value(s) Toxicity common at levels >20 mg/dL.
In susceptible individuals, any amount in plasma may be
associated with toxicity.
Increased levels • Accidental ingestion (e.g., by a child)
• Intentional overdose
• Abuse in place of ethanol
Decreased levels Not applicable
Interfering factors Plasma level may be below assay’s limit of detection even
though patient shows signs of toxicity.
Cross-references Ethylene Glycol Poisoning
Osmolality
ARUP Laboratories: Ethylene glycol, in Lab Test Directory. Salt Lake City, UT, ARUP Laboratories, 2021.
Available at: https://ltd.aruplab.com/Tests/Pub/0090110. Accessed June 2021.
Barceloux DG, Krenzelok EP, Olson K, Watson W: American Academy of Clinical Toxicology practice
guidelines on the treatment of ethylene glycol poisoning. Ad Hoc Committee. J Toxicol Clin Toxicol
37:537–560, 1999
Bobbitt WH, Williams RM, Freed CR: Severe ethylene glycol intoxication with multisystem failure. West
J Med 144:225–228, 1986
Brent J: Current management of ethylene glycol poisoning. Drugs 61:979–988, 2001
https://t.me/med1917
120 Laboratory Medicine in Psychiatry and Behavioral Science
Event-related potential (ERP) testing
Type of test Neurophysiology
Background and explanation
of test
Whereas evoked potential testing involves stimuli intro-
duced to test the integrity of primary sensory pathways,
ERP testing introduces an anomaly into the stimulus set so
that the brain’s processing of that anomaly can be examined.
The anomaly can be as simple as a rare or unexpected tone,
and in response to the tone, a late-appearing wave known
as the P300 (or P3) is generated. The stimulus set is repeated
many times, and the responses are averaged so that the tar
-
get waveform can be distinguished from background EEG
activity, which varies from sample to sample. The P300 and
other late-appearing waves reflect higher-order cognitive
processes such as selective attention, language processing,
and decision-making.
Relevance to psychiatry and
behavioral science
ERP testing has been used clinically to assist in the evalua-
tion of patients who are unable to undergo cognitive testing
to determine whether problems reside in language only, in
-
volve more global cognitive deficits, or involve a primary
psychiatric disorder such as depression or psychosis.
Preparation of patient Hair should be washed and rinsed before testing, but hair
products other than shampoo should not be used.
Indications Suspected dementia in absence of confirmatory cognitive
testing
Reference range Depends on testing protocol
Critical value(s) None
Abnormal test Abnormal ERP latencies have been identified in conditions
such as the following:
• Alzheimer’s disease
• Schizophrenia
• Metabolic encephalopathy (delirium)
• Brain tumor
• Hydrocephalus
• Epilepsy
Interfering factors None
Cross-references Evoked Potential Testing
Bennys K, Portet F, Touchon J, et al: Diagnostic value of event-related evoked potentials N200 and P300
subcomponents in early diagnosis of Alzheimer’s disease and mild cognitive impairment. J Clin Neu
-
rophysiol 24:405–412, 2007
Daube JR: Clinical Neurophysiology. Philadelphia, PA, FA Davis, 1996
https://t.me/med1917
121 Laboratory Tests
Evoked potential (EP) testing
Type of test Neurophysiology
Background and explanation
of test
In EP testing, electroencephalographic electrodes are placed
at specific sites on the scalp, and the brain’s electrical re
-
sponse to stimuli such as clicks, checkerboard pattern
flashes, or electrical stimulation is captured digitally for
computerized analysis. The latency of the response yields
information about the integrity of the tested sensory circuit.
Three circuits are commonly tested: brainstem auditory,
somatosensory, and visual. Indications are listed below.
Relevance to psychiatry and
behavioral science
Evoked responses are usually ordered in consultation with
a neurologist or neurosurgeon. These tests may be useful in
the evaluation of children with hearing impairment or de-
velopmental language problems. Less commonly, the tests
are used in the evaluation of patients with disorders mani
-
festing as sensorimotor symptoms in the extremities, to ex-
clude functional neurological symptom disorders.
Preparation of patient Hair should be washed and rinsed before testing, but hair
products other than shampoo should not be used.
Indications Brainstem auditory evoked response
• Evaluation of coma and coma-like states (brain death vs.
reversible coma)
• Suspected neurological hearing impairment
• Evaluation of children with language impairment
• Evaluation of mass lesions of cerebellopontine angle or
brainstem
• Multiple sclerosis
• Brainstem stroke
• Migraine headaches
• Evaluation of acoustic neuroma
Somatosensory evoked response
• Spinal cord lesions
• Spinal cord stroke
• Weakness or numbness of extremities
Visual evoked response
• Diagnosis of lesions involving optic nerve and tracts
• Multiple sclerosis
Reference range Normal values for each wave in complex waveform re-
sponses included in lab report
Critical value(s) None
Abnormal test See Indications section above.
Interfering factors None
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