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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_208_библиотеки_им_акад_М_И_Перельмана
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2 Laboratory Medicine in Psychiatry and Behavioral Science
Adrenocorticotropic hormone (ACTH)
Type of test Blood
Background and explanation
of test
ACTH produced in the pituitary acts on the adrenal glands
to stimulate the production of cortisol. The ACTH level in
-
creases when systemic cortisol levels are low and decreases
when cortisol levels are high. Cortisol regulation is a critical
component of homeostasis, because this hormone functions
to maintain blood pressure; control metabolism of glucose,
protein, and lipids; and assist in regulating the immune re
-
sponse. A normal diurnal variation is seen with ACTH, with
peak levels occurring before 8:00
A.M. and trough levels be-
fore 11:00
P.M. Diurnal variation of cortisol levels naturally
follows this variation of ACTH levels, with a slight time lag.
In patients with suspected adrenal insufficiency or sus-
pected Cushing’s syndrome, stimulation tests are given to
confirm the diagnosis and to determine the cause.
• ACTH stimulation test (also known as cosyntropin or
Cortrosyn test): Cosyntropin is a compound that acts as
an ACTH analogue, stimulating the adrenal glands to
produce cortisol. If cortisol levels remain low with stim-
ulation, the patient has primary adrenal failure (Addi-
son’s disease).
• Dexamethasone suppression test: This steroid feeds
back to the pituitary to stop ACTH production. If corti-
sol remains high, the adrenal glands themselves are pro-
ducing too much cortisol.
Relevance to psychiatry and
behavioral science
The ACTH level is increased when a person is under stress
or using amphetamines, steroids, alcohol, or lithium. ACTH
drives cortisol production and secretion, and excess or defi
-
cient cortisol causes symptoms that could be mistaken for a
primary psychiatric condition.
Preparation of patient The patient should follow a low carbohydrate diet for
48 hours before testing and should avoid stress for 12 hours
before testing.
Indications ACTH level is checked to diagnose and monitor disorders
involving abnormal cortisol levels. This test is indicated for
the following patients:
• Those with signs and symptoms of hypercortisolism, in-
cluding hypertension, hypokalemia, hyperglycemia,
truncal obesity, moon facies, abdominal striae, hirsut
-
ism, skin thinning, acne, and weakness
• Those with signs and symptoms of hypocortisolism, in-
cluding hypotension, hyperkalemia, hypoglycemia, hy-
ponatremia, hypercalcemia, fatigue, loss of appetite,
weight loss, and skin hyperpigmentation in nonexposed
areas
https://t.me/med1917
3 Laboratory Tests
Adrenocorticotropic hormone (ACTH) (continued)
Indications (continued) • Those with signs and symptoms of hypopituitarism, in-
cluding fatigue, weight loss, frequent nocturia, men-
strual irregularities, hypogonadism, and decreased
libido
Reference range 8:00
A.M. (peak): 25–100 pg/mL
6:00
P.M. (trough): 0–50 pg/mL
For ACTH stimulation test, cortisol >20 μg/dL
See Dexamethasone Suppression Test entry for that refer-
ence range.
Critical value(s) None
Increased levels • Addison’s disease (with low cortisol)
• Pituitary Cushing’s syndrome (with high cortisol)
• Ectopic ACTH production (with high cortisol)
•Pituitary adenoma
•Stress
Decreased levels • Adrenal tumor (with high cortisol)
• Hypopituitarism (with low cortisol)
Interfering factors Drugs that increase the ACTH level include amphetamines,
steroids, alcohol, lithium, insulin, levodopa, metoclopramide,
and RU 486.
Drugs that decrease the ACTH
level include dexamethasone,
other cortisol-like drugs (including prednisone, hydrocorti-
sone, prednisolone, and methylprednisolone), and mege-
strol acetate.
Cross-references Adrenal Insufficiency
Cortisol
Cushing’s Syndrome
Dexamethasone Suppression Test
American Association for Clinical Chemistry: Testing.com. Available at: https://www.testing.com. Ac-
cessed May 2021.
Dorin RI, Qualls CR, Crapo LM: Diagnosis of adrenal insufficiency. Ann Intern Med 139:194–204, 2003
Garcia C, Biller BM, Klibanski A: The role of the clinical laboratory in the diagnosis of Cushing syndrome.
Am J Clin Pathol 120(suppl):S38–S45, 2003
Karaca Z, Grossman A, Kelestimur F: Investigation of the hypothalamo-pituitary-adrenal (HPA) axis: a
contemporary synthesis. Rev Endocr Metab Disord 22(2):179–204, 2021
Khare S, Anjum F: Adrenocorticotropic hormone test, in StatPearls. Treasure Island, FL, StatPearls Publish-
ing, 2021. Available at: https://www.statpearls.com/ArticleLibrary/viewarticle/20072. Accessed
May 2021.
Malabanan AO, Meikle AW, Swenson L: Endocrine Disorders: Choose the Right Tests. The Primary Care
Guide to Diagnostic Testing. Columbus, OH, Anadem, 2004
Thomas Z, Fraser GL: An update on the diagnosis of adrenal insufficiency and the use of corticotherapy
in critical illness. Ann Pharmacother 41:1456–1465, 2007
https://t.me/med1917
4 Laboratory Medicine in Psychiatry and Behavioral Science
Alanine transaminase (ALT)
Type of test Blood
Background and explanation
of test
ALT is one of two transaminases—liver enzymes involved in
amino acid metabolism and cellular energy production. Un
-
like AST, ALT is primarily localized to the liver. Under nor-
mal conditions, ALT levels in blood are low. When the liver
is injured, ALT is released into the circulation and provides
an early sign of this injury before clinical symptoms develop.
Extreme elevations of ALT (>10 times normal) usually sug-
gest acute hepatitis, often viral in origin. In this condition,
ALT levels can remain high for as long as 6 months. In chronic
hepatitis, on the other hand, ALT levels may be only mini
-
mally elevated (<4 times normal) or even high-normal. The
most common cause of mild ALT elevation in the Western
hemisphere is non-alcoholic fatty liver disease. In liver dis
-
ease such as cirrhosis or biliary obstruction, ALT levels may
be normal.
ALT values are usually considered in relation to
other LFTs
such as
AST and
ALP. In alcoholic liver disease, the ratio of
AST to ALT is high (2:1 or more), even when neither value is
elevated. AST is more
sensitive to alcoholic liver disease, but
ALT is more specific. I
n
extrahepatic biliary obstruction,
ALT
is
usually more elevated than AST. In acute MI, AST is always
elevated, but
ALT is not unless there is
also
liver injury.
Relevance to psychiatry and
behavioral science
ALT is one
of the tests of liver health (liver “function”) that is
closely monitored in psychiatric practice, mainly because of
the potential hepatotoxicity of psychotropic drugs. ALT is
also monitored i
n
patients with alcohol use disorder
(AUD),
substance-induced liver disease, and hepatitis.
Elevation of ALT may be found on routine screening. If the
patient has no clinical symptoms and no risk factors for liver
disease, and ALT is <3 times the upper limit of normal
(ULN), a recheck is indicated after 1–3 months. If the eleva
-
tion persists, further investigation is needed.
If ALT is >3 times the ULN on a single
measurement, further
investigation is needed.
Elevation of ALT may occur with initiation of a new psycho-
tropic medication. In most cases, that ALT increase is benign,
and the laboratory value will revert to baseline within weeks
of dosage stabilization. Further investigation is needed
if the
value does not normalize or when ALP or bilirubin is also
elevated.
Pathological elevation of ALT may occur with AUD, sub-
stance-induced liver disease, or hepatitis. It is important not
to be misled by a normal ALT value in a patient with estab
-
lished cirrhosis.
In patients with cirrhosis due to hepatitis C who have a nor-
mal ALT result, active hepatitis may be present, such that
they would benefit from antiviral therapy, β-blockers to pre-
vent variceal bleeding, and other treatments.
https://t.me/med1917
5 Laboratory Tests
Alanine transaminase (ALT) (continued)
Relevance to psychiatry and AST and ALT levels may also be normal in patients with he-
behavioral science (continued) mochromatosis, in those receiving methotrexate, or after je-
junoileal bypass surgery despite advanced liver disease. In
all cases, the patients’ history should be considered and an
effort made to identify other evidence of liver disease.
Preparation of patient None needed
Indications • Component of LFT panel
• Component of CMP
• Monitoring medication effects on the liver
• Clinical symptoms of liver disease such as jaundice, abdom-
inal pain, ascites, nausea, vomiting, or darkening of urine
• Distinguishing hemolytic jaundice from jaundice due to
liver dysfunction
• Evaluating patients with hepatitis exposure or symptoms of
hepatitis
• Evaluating patients with AUD or other substance abuse
• Monitoring effects of treatment for liver disease
Reference range Males: 10–40 U/L
Females: 7–35 U/L
Normal values may vary with testing method.
Critical value(s) >300 IU/L indicates acute hepatic injury.
Increased levels • Acute viral, infectious, ischemic, or toxic hepatitis (30–
50 times normal)
• Hepatic necrosis due to drugs (e.g., acetaminophen)
• Hepatocellular disease (moderate to marked increase)
• Alcoholic cirrhosis (mild increase)
• Metastatic liver disease (mild increase)
• Biliary obstruction (mild increase)
• Fatty liver (mild increase)
• Mild increase (<1.5× ULN) can be normal for sex, ethnic-
ity, or BMI
Decreased levels Certain drugs can falsely decrease levels, as noted below.
Interfering factors Levels are normally slightly higher in males and Blacks.
Many psychotropic drugs can falsely elevate ALT values.
Aspirin, interferon, phenothiazines, and simvastatin can
falsely reduce ALT values.
Cross-references Alcohol Use Disorder
Aspartate Transaminase
Cirrhosis
Fatty Liver Disease
Hepatitis, Viral
Liver Function Tests
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6 Laboratory Medicine in Psychiatry and Behavioral Science
Alanine transaminase (ALT) (continued)
American Association for Clinical Chemistry: Testing.com. Available at: https://www.testing.com. Ac-
cessed May 2021.
Fischbach FT, Fischbach MA: A Manual of Laboratory and Diagnostic Tests, 10th Edition. Philadelphia,
PA, Wolters Kluwer Health/Lippincott Williams and Wilkins, 2018
Gopal DV, Rosen HR: Abnormal findings on liver function tests: interpreting results to narrow the diag-
nosis and establish a prognosis. Postgrad Med 107:100–102, 105–109, 113–114, 2000
Schreiner AD, Rockey DC: Evaluation of abnormal liver tests in the adult asymptomatic patient. Curr
Opin Gastroenterol 34(4):272–279, 2018
Theal RM, Scott K: Evaluating asymptomatic patients with abnormal liver function test results. Am Fam
Physician 53:2111–2119, 1996
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7 Laboratory Tests
Albumin
Type of test Blood
Background and explanation
of test
The most abundant protein in plasma, albumin serves pri-
marily to maintain oncotic pressure inside blood vessels to
keep them from becoming “leaky.” It has a similar function
in the urinary tract and for CSF. In addition, albumin trans
-
ports various drugs and nutrients, provides a source of
nourishment for tissues, and contributes to an acid-base
buffer system in the blood. Albumin is normally reabsorbed
in the kidneys, so undetectable levels are found in urine.
The presence of albumin in the urine (as microalbumin or
protein) presages or indicates kidney dysfunction. Albumin
may also be lost from the blood through the GI tract or the
skin or because of hemorrhage.
The serum albumin level is highly correlated with future
morbidity and mortality, not only in ill patients but also in
seemingly healthy patients. It is such a strong predictor of
poor surgical outcome that surgery may be postponed or
canceled in the face of low values. Even so, attempts to im-
prove nutritional status and thus raise serum albumin levels
have not been successful. In fact, it is now known that serum
albumin concentration correlates poorly with general nutri
-
tional status, such that serum albumin is no longer consid-
ered a reliable marker of undernutrition.
Relevance to psychiatry and
behavioral science
Although serum albumin is routinely checked as part of the
CMP, its clinical value has been questioned. The albumin
level may be low in numerous disease states, most promi-
nently liver disease, but the finding of low albumin helps
little with differential diagnosis. Contrary to previous teach
-
ings, the albumin level does not decline significantly in
chronic anorexia nervosa, possibly because of replacement
by protein released
from muscle breakdown.
The albumin level can assist in the interpretation of border-
line-normal calcium levels, as discussed in other tables. In
addition, low albumin is of importance in psychopharma
-
cology, in the interpretation of drug levels for highly pro-
tein-bound drugs. When the albumin level is low, the
unbound percentage of these drugs is higher, and the mea
-
sured concentration of total drug may underestimate the
amount of drug acting on the target organ. In this case, the
patient could develop symptoms of toxicity at apparently
therapeutic levels. Free drug levels, which are available for
many psychotropics, can be helpful in this situation.
Preparation of patient None needed
Indications Routine component of CMP
Reference range Adults: 3.5–5.2 g/dL
Recent research suggests that the lower limit of normal for
serum albumin may more appropriately be set at 4.3 g/dL
than the accepted value of 3.5 g/dL because values between
3.5 g/dL and 4.3 g/dL are still associated with relatively
high mortality rates.
https://t.me/med1917
8 Laboratory Medicine in Psychiatry and Behavioral Science
Albumin (continued)
Critical value(s) <1.5 g/dL (<15 g/L)
Levels of 2.0–2.5 g/dL may be associated with edema.
Increased levels Dehydration
Decreased levels • Schizophrenia, major depression
• Liver damage, cirrhosis, alcohol use disorder
• Nephrotic syndrome, renal disease
• Inflammatory bowel disease
• Heart failure
•Burns
• Severe skin disease
• Low-protein, normal calorie diet (Kwashiorkor)
• Acute inflammation
• Chronic inflammation
• Thyroid disease: Cushing’s disease, thyrotoxicosis
• Prolonged hospitalization or bed rest
Interfering factors Level declines slowly after age 40 years. Decreased albumin
levels occur in the last trimester of pregnancy.
Drugs that increase albumin levels include anabolic ste-
roids, androgens, growth hormones, and insulin.
Drugs that decrease albumin levels include estrogens.
IV fluids may invalidate results because of dilutional effects.
Cross-references Alcohol Use Disorder
Comprehensive Metabolic Panel
Protein, Serum
American Association for Clinical Chemistry: Testing.com. Available at: https://www.testing.com. Ac-
cessed May 2021.
Boldt J: Use of albumin: an update. Br J Anaesth 104:276–284, 2010
Fischbach FT, Fischbach MA: A Manual of Laboratory and Diagnostic Tests, 10th Edition. Philadelphia,
PA, Wolters Kluwer Health/Lippincott Williams and Wilkins, 2018
Levitt DG, Levitt MD: Human serum albumin homeostasis: a new look at the roles of synthesis, catabo-
lism, renal and gastrointestinal excretion, and the clinical value of serum albumin measurements. Int
J Gen Med 9:229–255, 2016
https://t.me/med1917
9 Laboratory Tests
Aldosterone
Type of test Blood
Background and explanation
of test
Aldosterone is a steroid hormone produced in the adrenal
cortex that regulates sodium retention and potassium excre
-
tion by the kidneys along with blood volume and blood
pressure. Renin is an enzyme released by the kidneys when
blood pressure drops that initiates a chain of events result
-
ing in aldosterone production. In healthy individuals, when
the renin level increases, the aldosterone level also increases.
In primary aldosteronism, aldosterone secretion is indepen
-
dent of renin secretion and is not suppressible. To differen-
tiate conditions associated with aldosterone abnormalities,
renin and cortisol levels are checked along with aldosterone.
Relevance to psychiatry and
behavioral science
When patients presenting with vague complaints of chronic
fatigue and muscle weakness in the context of refractory hy
-
pertension and hypokalemia are treated only symptomati-
cally, the underlying diagnosis of hyperaldosteronism may
be missed.
Preparation of patient Patients should avoid stress and strenuous exercise before
testing. They can be supine or sitting upright but should re
-
main in this position for 15–30 minutes before blood is
drawn. Salt intake for 2 weeks before testing should be nor-
mal. If patient is hypokalemic, potassium should be re-
placed before testing.
Indications • Signs and symptoms of hyperaldosteronism, including
hypertension, fatigue, weakness, and low potassium
• Suspected adrenal insufficiency
Reference range Upright position, adults: 7–30 ng/dL
Supine position, adults: 3–16 ng/dL
Values are 3–5 times higher with a low-sodium diet.
Critical value(s) None
Increased levels • Primary aldosteronism or Conn’s syndrome: high aldo-
sterone, low renin, and normal cortisol
• Secondary aldosteronism: high aldosterone, high renin,
and normal cortisol
Decreased levels • Cushing’s syndrome: aldosterone low to normal, renin
low, and cortisol high
• Adrenal insufficiency or Addison’s disease: aldosterone
low, renin high, and cortisol low
Interfering factors Factors affecting test results include salt intake, licorice in-
gestion, time of specimen collection, stress, posture, strenu-
ous exercise, severe illness, and certain drugs (NSAIDs,
diuretics, β-blockers, steroids, ACE inhibitors, and oral con-
traceptives).
Cross-references Adrenal Insufficiency
Cortisol
Cushing’s Syndrome
https://t.me/med1917
10 Laboratory Medicine in Psychiatry and Behavioral Science
Aldosterone (continued)
American Association for Clinical Chemistry: Testing.com. Available at: https://www.testing.com. Ac-
cessed May 2021.
Fischbach FT, Fischbach MA: A Manual of Laboratory and Diagnostic Tests, 10th Edition. Philadelphia,
PA, Wolters Kluwer Health/Lippincott Williams and Wilkins, 2018
Torpy DJ, Stratakis CA, Chrousos GP: Hyper- and hypoaldosteronism. Vitam Horm 57:177–216, 1999
Vaidya A, Carey RM: Evolution of the primary aldosteronism syndrome: updating the approach.J Clin
Endocrinol Metab 105(12):3771–3783, 2020 [published correction appears in J Clin Endocrinol Metab
106(1):e414, 2021]
White PC: Disorders of aldosterone biosynthesis and action. N Engl J Med 331:250–258, 1994
https://t.me/med1917
11 Laboratory Tests
Alkaline phosphatase (ALP)
Type of test Blood
Background and explanation
of test
ALP is an enzyme concentrated in osteoblasts (bone-forming
cells) and cells that form the bile canaliculi in the liver. Smaller
amounts of ALP are found in the placenta and bowel. Each of
these organs elaborates a different isoenzyme of ALP, which
can be distinguished by fractionation. Total ALP levels are
used to evaluate liver and bone disease, with high levels indi-
cating injury to one of these tissue s.
When ALP is elevated in tandem with other LFTs such as AST,
ALT, or bilirubin, the cause of the ALP elevation is usually
hepatic. In liver disease such as biliary obstruction, ALP and
bilirubin are increased out of proportion to increases in AST
or ALT. In hepatocellular liver injury such as occurs in hepa
-
titis, ALT and AST are increased out of proportion to ALP.
If the ALP level is high and the source of the elevation is un-
known, ALP can be fractionated or GGT can be assayed. GGT
is another enzyme produced in the liver that is not made by
bone. GGT elevation then indicates a hepatic source.
If ALP is elevated and calcium and phosphate levels are ab-
normal, the source is usually bone. Cancer metastatic to bone
or liver can cause elevation in ALP. With treatment, ALP lev
-
els may decline. In some bone diseases such as Paget’s dis-
ease, ALP may be the only laboratory abnormality, and the
elevation seen can be up to 25 times the normal value. ALP is
elevated in osteomalacia (bone softening) but not in osteopo
-
rosis, so the value can help distinguish these conditions.
Relevance to psychiatry and
behavioral science
Numerous psychotropic drugs are associated with increased
ALP levels. (See Interfering Factors section below.) A choles-
tatic drug reaction can be suggested by elevated ALP and
GGT along with either elevated transaminases or bilirubin
with a normal liver ultrasound. Alcohol overuse and cirrho
-
sis are both associated with ALP elevation. In alcohol-
related hepatitis, the ALP elevation is <2 times the upper
limit of normal (ULN), and this does not correlate well with
the bilirubin level.
Preparation of patient Overnight fasting before the test is preferred because en-
zyme activity is affected by eating, especially fatty food.
Indications • Component of the LFT panel
• Signs/symptoms of liver disease
• Signs/symptoms of bone disease
Reference range Adults: 25–100 U/L
ALP elevation may be found on routine screening.
• If ALP is <1.5 times the ULN, recheck in 1–3 months.
•If ALP is ≥ 1.5 times the ULN on two measurements
6 months apart, further investigation is needed.
• If ALP is >3 times the ULN on a single measurement,
further investigation is needed.
Critical value(s) None
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