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162 Laboratory Medicine in Psychiatry and Behavioral Science
Human growth hormone level (continued)
American Association for Clinical Chemistry: Testing.com. Available at: https://www.testing.com. Ac-
cessed July 2021.
Deal CL, Tony M, Höybye C, et al: Growth Hormone Research Society workshop summary: consensus
guidelines for recombinant human growth hormone therapy in Prader-Willi syndrome.J Clin Endo
-
crinol Metab 98(6):E1072–E1087, 2013
Fischbach FT, Fischbach MA: A Manual of Laboratory and Diagnostic Tests, 10th Edition. Philadelphia,
PA, Wolters Kluwer Health/Lippincott Williams and Wilkins, 2018
Melmed S: Pathogenesis and diagnosis of growth hormone deficiency in adults.N Engl J Med 380(26):2551–
2562, 2019
Siebert DM, Rao AL: The use and abuse of human growth hormone in sports.Sports Health 10(5):419–
426, 2018
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163 Laboratory Tests
Huntingtin gene mutation
Type of test Genetic
Background and explanation
of test
The huntingtin gene (HTT) codes for a protein with a critical
role in prenatal brain development. One area of the gene
contains a segment of DNA known as a CAG (cytosine
-
adenine-guanine) trinucleotide repeat that appears several
times in a row. A normal number of CAG repeats is 10–26.
When more repeats are present, the CAG segment becomes
unusually long. This elongated protein is processed into
smaller fragments that are neurotoxic, resulting in dysfunc
-
tion and death of neurons. The more repeats, the earlier the
onset of clinical Huntington’s disease (HD), although age at
onset is modified by environmental factors and variants
elsewhere in the genome.
As the mutation is passed to the next generation, the size of
the CAG repeat
segment often increases, a phenomenon
known as “anticipation.”
Early presentations of HD (age <20 years) are associated
with a wide range of cognitive, psychiatric, and motor
symptoms, whereas late presentations (age ≥60 years) are
marked by motor symptoms. This progression is mirrored
by neocortical atrophy, which occurs early in anterior areas
and late in occipital and parietal areas.
More sensitive testing methods as well a
s treatments that
partially reduce
variant HTT are under active
investigation.
Relevance to psychiatry and
behavioral science
Psychiatric symptoms of HD include irritability, depression,
psychosis, personality changes, apathy, and cognitive im
-
pairment. Depression and irritability can precede motor
symptoms by many years, whereas apathy and cognitive
impairment tend to occur after motor symptoms. Suicidal
ideation, suicide attempt, and completed suicide are more
common in HD patients than in the general population. In
-
voluntary movements such as chorea—the hallmark of
HD—may be subtle until later stages of the disease. Motor
abnormalities also include dystonia, ataxia, parkinsonism,
oculomotor problems, dysarthria, dysphagia, incoordina-
tion, clumsiness, and seizures.
Preparation of patient All patients require genetic counseling, both before and af-
ter testing.
Indications • Positive family history of HD confirmed by genetic testing
• Presence of mood, motor, and/or cognitive symptoms
suggestive of HD
• Presence of FTD/amyotrophic lateral sclerosis, with
concern for variant HTT
Positive test • 27–35 repeats: Patients will not develop HD, but children
are at risk because CAG repeat size may increase into
HD range as the gene is transmitted from parent to
child.
• 36–39 repeats: Patients may or may not develop HD.
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164 Laboratory Medicine in Psychiatry and Behavioral Science
Huntingtin gene mutation (continued)
Positive test (continued) •
≥
40 repeats: HD will develop.
•
≥
60 repeats: Early onset HD will develop.
Negative test A normal result is 10–26 CAG repeats.
Interfering factors None known
Cross-references Huntington’s Disease
De Luca A, Morella A, Consoli F, et al: A novel triplet-primed PCR assay to detect the full range of trinu-
cleotide CAG repeats in the huntingtin gene (HTT). Int J Mol Sci 22(4):1689, 2021
Dewan R, Chia R, Ding J, et al: Pathogenic huntingtin repeat expansions in patients with frontotemporal
dementia and amyotrophic lateral sclerosis.Neuron 109(3):448–460, 2021
Fischbach FT, Fischbach MA: A Manual of Laboratory and Diagnostic Tests, 10th Edition. Philadelphia,
PA, Wolters Kluwer Health/Lippincott Williams and Wilkins, 2018
Johnson EB, Ziegler G, Penny W, et al: Dynamics of cortical degeneration over a decade in Huntington’s
disease. Biol Psychiatry 89(8):807–816, 2021 [published correction appears in Biol Psychiatry
90(7):505, 2021].
Kachian ZR, Cohen-Zimerman S, Bega D, et al: Suicidal ideation and behavior in Huntington’s disease:
systematic review and recommendations. J Affect Disord 250:319–329, 2019
Leavitt BR, Kordasiewicz HB, Schobel SA: Huntingtin-lowering therapies for Huntington disease: a re-
view of the evidence of potential benefits and risks. JAMA Neurol 77(6):764–772, 2020 [published cor-
rection appears in JAMA Neurol 2020 77(8):1040]
McAllister B, Gusella JF, Landwehrmeyer GB, et al: Timing and impact of psychiatric, cognitive, and mo-
tor abnormalities in Huntington disease.Neurology 96(19):e2395–e2406, 2021
van der Plas E, Langbehn DR, Conrad AL, et al: Abnormal brain development in child and adolescent
carriers of mutant huntingtin. Neurology 93(10):e1021–e1030, 2019
https://t.me/med1917
165 Laboratory Tests
Iron level
Type of test Blood
Background and explanation
of test
Iron is an essential nutrient required for the production of
healthy RBCs. When iron is taken in from dietary sources,
very small amounts are absorbed. Iron is transported in the
body by the protein transferrin. Most of the iron in the blood
is incorporated into hemoglobin, which carries oxygen from
the lungs to tissue and helps to carry carbon dioxide back to
the lungs. Iron is stored in the liver and reticuloendothelial
tissues in the form of ferritin and hemosiderin and is re
-
leased from these stores as needed by the body.
Iron deficiency refers to the depletion of storage iron,
whereas anemia refers to a decrease in the amount of
hemoglobin in the blood. When iron stores are depleted,
anemia does not develop immediately, so early iron defi
-
ciency is often asymptomatic. When the hemoglobin level
drops to ≤10 g/dL, however, patients may begin to experi-
ence palpitations and fatigue. Then, with further lowering
of hemoglobin, shortness of breath, dizziness, headache,
and even angina may develop.
Chronic iron deficiency can be associated with pica (craving
for dirt, clay, or chalk), burning or smooth tongue, sores at
the corners of
the mouth,
and spoon-shaped nails.
When the serum iron level is checked in the workup of iron
deficiency or iron overload, serum ferritin, transferrin, and
total iron-binding capacity are also checked.
Relevance to psychiatry and
behavioral science
Both iron deficiency and iron overload (hemochromatosis)
are associated with psychiatric and behavioral symptoms.
Furthermore, an association between low iron levels and
schizophrenia has been discovered that is particularly
marked in patients with akathisia. The explanation for this
relationship is not known.
There is some evidence
that iron overload underlies liver
injury observed in COVID-19 patients.
Preparation of patient Some sources suggest that patients fast overnight and have
their blood drawn in the morning for iron testing. Patients
should not take iron supplements for 24 hours before test-
ing. If the patient has had a transfusion, several days should
elapse before testing.
Indications • Determining cause of anemia
• Monitoring treatment of iron deficiency
• Workup of suspected hemochromatosis
• Suspected iron poisoning
Reference range Adult males: 50–160 μg/dL
Adult females: 40–150 μg/dL
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166 Laboratory Medicine in Psychiatry and Behavioral Science
Iron level (continued)
Critical value(s) >300 μg/dL
Increased levels • Multiple blood transfusions
• Accidental overdose
• Iron injections
• Lead poisoning
• Hemochromatosis
• Acute hepatitis
• Aplastic anemia
• Hemolytic anemia
• Polycythemia
• Thalassemia
• Vitamin B
6
deficiency
• Nephritis
Decreased levels • Bleeding
• Pregnancy
• Burns
• Carcinoma
• Postoperative state
• Postgastrectomy
• Malnutrition
• Malabsorption
• Rheumatoid arthritis
• Schizophrenia
• Uremia
Interfering factors Specimen hemolysis invalidates test result.
Vitamin B
12
taken within 48 hours of testing may increase
iron level.
Cross-references Anemia
Hemochromatosis
Pica
American Association for Clinical Chemistry: Testing.com. Available at https://www.testing.com. Ac-
cessed July 2021.
Del Nonno F, Nardacci R, Colombo D, et al: Hepatic failure in COVID-19: is iron overload the dangerous
trigger? Cells 10(5):1103, 2021
Fischbach FT, Fischbach MA: A Manual of Laboratory and Diagnostic Tests, 10th Edition. Philadelphia,
PA, Wolters Kluwer Health/Lippincott Williams and Wilkins, 2018
Kuloglu M, Atmaca M, Ustundag B, et al: Serum iron levels in schizophrenic patients with or without
akathisia. Eur Neuropsychopharmacol 13:67–71, 2003
Tojo K, Sugawara Y, Oi Y, et al: The U-shaped association of serum iron level with disease severity in
adult hospitalized patients with COVID-19.Sci Rep 11(1):13431, 2021
https://t.me/med1917
167 Laboratory Tests
Lipase
Type of test Blood
Background and explanation
of test
Lipase is a pancreatic enzyme involved in the metabolism of
long-chain fatty acids. With pancreatic injury, the lipase
level in the circulation rises. When the level is ≥3 times the
upper limit of normal (ULN), acute pancreatitis may be di
-
agnosed in the presence of typical symptoms such as epigas-
tric pain, nausea, and vomiting. The lipase level in this
condition rises within 4–8 hours, peaks at 24 hours, and nor
-
malizes over the following 8–14 days. Because the duration
of the lipase elevation is longer than that of amylase, lipase
is the preferred test for pancreatitis. Past practice has been
to check both amylase and lipase simultaneously, but this
has been found to be unnecessary. Rechecking lipase (or am
-
ylase) in the course of illness is also unnecessary.
Relevance to psychiatry and
behavioral science
Patients at risk for pancreatitis include those with alcohol
use disorder (especially males), gallstones (especially fe-
males), and hyperlipidemia and those treated with medica-
tions such as valproate, corticosteroids, or isoniazid.
A false-positive report of pancreatitis can occur with other
serious conditions such as bowel obstruction or peritonitis,
so it is important to consider the differential diagnosis. On
the other hand, a false-negative report could delay critical
treatment for pancreatitis, so
the sta
ndard of care is to admit
and treat patients who demonstrate typical symptoms, even
if their lipase level does not meet the criterion.
In patients admitted to the hospital with COVID-19 infec-
tion, elevated lipase levels predict a more severe course of
illness, often with ICU admission and intubation.
Preparation of patient None needed
Indications Clinical suspicion of pancreatitis
Reference range Normal values vary according to
testing method and age of
patient; consult lab report for normal range.
≥3 times the ULN is consistent with acute pancreatitis.
Critical value(s) >600 IU/L
Increased levels • Pancreatitis
• Chronic renal failure
• Pancreatic carcinoma
• Cholecystitis
• Hemodialysis
• Bowel obstruction or infarction
• Peritonitis
• Primary biliary cirrhosis
Decreased levels Not applicable
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168 Laboratory Medicine in Psychiatry and Behavioral Science
Lipase (continued)
Interfering factors EDTA anticoagulant interferes with test.
Drugs associated with increased lipase levels include clo-
zapine, desipramine, donepezil, mirtazapine, risperidone,
valproate, many opioids, and numerous non-psychotropics,
including acetaminophen, NSAIDs, and steroids.
Drugs associated with decreased lipase levels include cal-
cium, hydroxyurea, mesalamine, protamine, and somato-
statin.
Cross-references Amylase
Pancreatitis, Acute
Aljomah AS, Hammami MM: Superfluous amylase/lipase testing at a tertiary care hospital: a retrospec-
tive study. Ann Saudi Med 39(5):354–358, 2019
Barlass U, Wiliams B, Dhana K, et al: Marked elevation of lipase in COVID-19 disease: a cohort study.
Clin Transl Gastroenterol 11(7):e00215, 2020
Cappell MS: Acute pancreatitis: etiology, clinical presentation, diagnosis, and therapy. Med Clin North
Am 92:889–923, 2008
Fischbach FT, Fischbach MA: A Manual of Laboratory and Diagnostic Tests, 10th Edition. Philadelphia,
PA, Wolters Kluwer Health/Lippincott Williams and Wilkins, 2018
Hameed AM, Lam VW, Pleass HC: Significant elevations of serum lipase not caused by pancreatitis: a
systematic review. HPB (Oxford) 17(2):99–112, 2015
Matull WR, Pereira SP, O’Donohue JW: Biochemical markers of acute pancreatitis. J Clin Pathol 59:340–
344, 2006
Ritter JP, Ghirimoldi FM, Manuel LSM, et al: Cost of unnecessary amylase and lipase testing at multiple
academic health systems.Am J Clin Pathol 153(3):346–352, 2020
Rompianesi G, Hann A, Komolafe O, et al: Serum amylase and lipase and urinary trypsinogen and am-
ylase for diagnosis of acute pancreatitis. Cochrane Database Syst Rev 4(4):CD012010, 2017
https://t.me/med1917
169 Laboratory Tests
Lipid panel
Type of test Blood
Background and explanation
of test
A standard lipid panel includes total cholesterol, low-density
lipoprotein cholesterol (LDL-C), high-density lipoprotein
cholesterol (HDL-C), and triglycerides (TG). LDL-C—the
primary target for lowering the risk of coronary heart disease
and stroke—can be calculated or measured directly. The cal
-
culated value for LDL-C is valid only if the TG content is
<400 mg/dL. With higher TG values, LDL-C is measured di
-
rectly. LDL-C is highly correlated with the risk of atheroscle-
rotic cardiovascular disease. The lower the LDL-C level, the
better, at least down to ~40 mg/dL. Guidelines emphasize
the importance of treating to get LDL-C levels as
low as
possible. U.S. guidelines suggest a target LDL-C level for
very-high-risk patients of <70 mg/dL, whereas European
guidelines suggest a target of <55 mg/dL. Both guidelines
recommend at least a 50% reduction in LDL-C. In addition to
dietary and other lifestyle
interventions, LDL-C-lowering
drugs such as PCSK9 inhibitors are now available to help
achieve these endpoints.
Hypertriglyceridemia identified from non-fasting blood sam-
ples is also associated with increased cardiovascular and
stroke risk, with the risk of an adverse event doubled for
those with TG ≥171 mg/dL. Fasting TG levels are less predic
-
tive. Very elevated non-fasting TG levels (≥ 500 mg/dL) also
increase the risk of pancreatitis.
HDL-C level is inversely related to coronary risk; interven-
tion may be indicated when this value is low.
Healthy adults should have their lipid profile checked every
4–6 years. After age 40, a 10-year cardiac risk assessment
should be performed that can guide further testing and treat
-
ment.
Relevance to psychiatry and
behavioral science
Many psychotropic medications—particularly atypical anti-
psychotics and antidepressants—have adverse effects on cho
-
lesterol levels. In addition, certain psychiatric patient
populations are at high risk of lipid abnormalities, obesity,
and the metabolic syndrome.
Preparation of patient Fasting is no longer recommended before lipid testing
Indications • Routine health screening for all adults ≥20 years of age,
obtained every 4–6 years; more often for those at higher
risk (e.g., with diabetes, known heart disease, or family
history of high cholesterol)
• Lipid panel 1–3 months after intervention to lower lipid
levels
Reference range Total cholesterol: <200 mg/dL
LDL-C: <100 mg/dL
HDL-CL ≥60 mg/dL
TG: <150
mg/dL
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170 Laboratory Medicine in Psychiatry and Behavioral Science
Lipid panel (continued)
Critical value(s) Total cholesterol: ≥240 mg/dL
LDL-C: ≥160 mg/dL
HDL-C: ≤39 mg/dL
TG: ≥200 mg/dL
Increased levels • Familial hyperlipidemias
• Glycogen storage disease
• Coronary heart disease
• Obstructive liver disease
• Primary biliary cirrhosis
• Nephrotic syndrome
• Chronic renal failure
• Cushing’s syndrome
• Diabetes, type 2
• Anorexia nervosa
• Hypothyroidism
• Obesity
• Pregnancy
• Drugs: levodopa, phenytoin
Decreased levels • Tangier disease
• Abetalipoproteinemia, hypobetalipoproteinemia
• Hepatocellular necrosis
• Hepatitis
• Porphyria
• Tuberculosis
• Malignancy
• Hyperthyroidism
• Malabsorption
• Malnutrition
• Severe acute illness
• Cirrhosis
• Depression, suicidal behavior
• Epilepsy
• Pernicious anemia
• Inflammation
• Infection
• Drugs: haloperidol, MAOIs
https://t.me/med1917
171 Laboratory Tests
Lipid panel (continued)
Interfering factors High TG concentrations the affect accuracy of methods used
by many laboratories to calculate LDL-C.
Drugs associated with reduced cholesterol levels include
thyroid hormone and all cholesterol-lowering treatments.
Drugs associated with increased cholesterol levels include
carbamazepine, steroids, levodopa, phenothiazines, and
HIV protease inhibitors.
Cross-references Cardiovascular Risk Assessment (Appendix C)
Metabolic Syndrome
Triglycerides
Atar D, Jukema JW, Molemans B, et al: New cardiovascular prevention guidelines: how to optimally man-
age dyslipidaemia and cardiovascular risk in 2021 in patients needing secondary prevention? Athero-
sclerosis 319:51–61, 2021
Doran B, Guo Y, Xu J, et al: Prognostic value of fasting versus nonfasting low-density lipoprotein choles-
terol levels on long-term mortality: insight from the National Health and Nutrition Examination Sur-
vey III (NHANES-III).Circulation 130(7):546–553, 2014
Fischbach FT, Fischbach MA: A Manual of Laboratory and Diagnostic Tests, 10th Edition. Philadelphia,
PA, Wolters Kluwer Health/Lippincott Williams and Wilkins, 2018
Oh RC, Trivette ET, Westerfield KL: Management of hypertriglyceridemia: common questions and an-
swers. Am Fam Physician 102(6):347–354, 2020
https://t.me/med1917
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