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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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282 Laboratory Medicine in Psychiatry and Behavioral Science
Urine dipstick testing
Type of test Urine
Background and explanation
of test
Dipstick testing is a quick and inexpensive way to test urine
for infection and other abnormalities without the need to
involve the laboratory. Specific instructions for test kits
must be followed to ensure the accuracy of the results, and
interpretation is made in the context of clinical signs and
symptoms.
Relevance to psychiatry and
behavioral science
This test could be conducted in the outpatient office setting.
It may be of particular use to physicians caring for geriatric
patients.
Preparation of patient Follow test kit instructions.
Indications Suspected uncomplicated urinary tract infection (UTI)
Normal test A dipstick test that is negative for leukocyte esterase (LE)
and nitrite has a negative predictive value (i.e., absence of
UTI) of ≥95%.
Abnormal test • If either nitrite or LE and blood are positive, UTI is
probable.
• If nitrite, LE, blood, and protein are all negative, UTI is
unlikely. Urethral syndrome may be present.
• If nitrite is negative and either LE or blood is positive,
UTI or urethral syndrome is probable.
• If nitrite, LE, and blood are all negative but protein is pos-
itive, a diagnosis other than UTI should be suspected.
Interfering factors If the test kit instructions are not followed, results may not
be valid. Unless the first morning urine specimen is used,
nitrite testing may yield false-negative results. If infecting
bacteria do not reduce urinary nitrates, nitrite testing may
yield false-negative results.
Cross-references Urinalysis
Urinary Tract Infection
Urine Blood, Hemoglobin, and Myoglobin
Urine Leukocyte Esterase
Urine Nitrite
Urine Protein
Devillé WL, Yzermans JC, van Duijn NP, et al: The urine dipstick test useful to rule out infections: a meta-
analysis of the accuracy.BMC Urol 4:4, 2004
Fischbach FT, Fischbach MA: A Manual of Laboratory and Diagnostic Tests, 10th Edition. Philadelphia,
PA, Wolters Kluwer Health/Lippincott Williams and Wilkins, 2018
Simerville JA, Maxted WC, Pahira JJ: Urinalysis: a comprehensive review. Am Fam Physician 71:1153–
1162, 2005
https://t.me/med1917
283 Laboratory Tests
Urine drug screen
Type of test
Background and explanation
of test
Urine
Screening for drugs of abuse can be performed on blood,
urine, hair, nails, and breath. Urine is most commonly used
because it is easy to obtain and has a reasonable window of
detection for clinical purposes. For initial screening, urine
dipstick tests are often used. These are immunoassays that
return positive results when specified thresholds are ex-
ceeded. These tests are prone to false-negative and false-
positive results, so they must be followed up with more
sensitive and specific tests that use gas chromatography/
mass spectrometry or high-performance liquid chromatogra-
phy. These methods return quantitative results and identify
the specific drugs detected.
Although drug tests can be ordered individually, more often
a standard panel of drugs is requested. For use in medical
and mental health settings, that panel usually includes
opioids, cocaine, amphetamines, barbiturates, benzodiaze
-
pines, phencyclidine (PCP), and cannabinoids (THC).
Alcohol may or may not be included, depending on the
laboratory protocol and panel requested. Standard panels
often do not include “club drugs” such as MDMA (Ecstasy),
gamma-hydroxybutyrate (GHB), flunitrazepam (Rohyp
-
nol), and ketamine or synthetic opioids such as fentanyl,
methadone, and buprenorphine. Sensitivity to semisyn
-
thetic opioids such as oxycodone and hydrocodone may be
low, such that specific drug testing may be needed. All of
these issues should be discussed with the laboratory before
the specimen is collected. For GHB, the half-life of the drug
is so short that detection is always difficult.
Complicating the interpretation of opioid screening results is
the fact that some opioids are metabolized to other opioids,
such that their presence may indicate metabolism rather than
additional abuse. For example, if free morphine as a percent-
age of free codeine is <55%, the morphine may be a product
of codeine metabolism. The detection of 6-acetylmorphine
with morphine is definitive evidence of heroin use, but this
intermediate metabolite is short-lived (<8 hours).
Urine testing for buprenorphine can be requested, either to
screen for illicit use or to confirm compliance with treatment.
The major metabolite norbuprenorphine should be included.
Urine methadone screening is subject to confounding by pa
-
tients who are diverting the drug and then adding metha-
done itself to the urine sample. In this case, the metabolite
EDDP (2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine)
could be tested; its presence indicates that methadone has
been taken and metabolized.
https://t.me/med1917
284 Laboratory Medicine in Psychiatry and Behavioral Science
Urine drug screen (continued)
Background and explanation
of test (continued)
Most urine assays for benzodiazepines are designed to detect
only diazepam, nordiazepam, and oxazepam. Metabolites of
alprazolam, lorazepam, and clonazepam are often not de
-
tected, but the par ent drugs may be detectable if the cutoff for
detection is lowered because only a small proportion of these
drugs is excreted unchanged. A lower cutoff may also be
required for very potent drugs, such as alprazolam, because
only small doses are used.
Interpretation of screening results for the stimulants amphet-
amine and methamphetamine is difficult because of poor
specificity; positive results should be confirmed with quanti
-
tative testing. Methylphenidate detection requires a separate
test. With cocaine, on the other hand, the detection of the
metabolite benzoylecgonine is straightforward.
Urine screening for marijuana use detects a metabolite of
THC, with the window of detection dependent on the pattern
of use, ranging from 3 days in a one-time user to 30 days in a
heavy, chronic user. Positive results are unlikely to be found
from passive inhalation. Testing for synthetic cannabinoids
(e.g., Spice, K2) is not routine but can be specifically re-
quested.
Urine detection windows for various drugs are shown in a
table prepared by ARUP Laboratories, which at this writing
can be found at
www.aruplab.com/files/resources/
pain-management/DrugAnalytesPlasmaUrine.pdf.
Relevance to psychiatry and
behavioral science
Urine drug screening is commonly used in the emergency
setting and in general psychiatry and substance abuse treat
-
ment settings. Screening can detect illicit drug use or confirm
compliance with treatment (e.g., with methadone). Screen-
ing can also flag possible diversion of prescribed medication.
Use in occupational and forensic settings involves different
protocols and detection cutoff levels and is not covered here.
Unobserved urine sampling can result in false-negative re-
sults because of tampering (e.g., diluting urine). In these
cases, a simultaneous urinalysis can assist in interpretation.
A comprehensive history of recent substances used (includ-
ing over-the-counter drugs) can help in the interpretation of
false-positive results.
Preparation of patient Patients should be informed of the reason for drug testing,
and agreement should be made as to how the results will be
used and who will see them. The consequences of interfering
with drug testing (e.g., diluting urine) should be made clear.
Indications • Patient in emergency setting with unexplained symptoms
• Patient in emergency setting after an accident in which
alcohol or substance use is suspected
• Patient suspected of drug use
• Pregnant patient at risk of drug use
• Monitoring a known drug user
https://t.me/med1917
285 Laboratory Tests
Urine drug screen (continued)
Reference range Refer to lab documentation.
Critical value(s) Not applicable
Positive test Positive screening tests are confirmed by more sensitive and
specific assays. Positive confirmation in the absence of con
-
founding factors means the patient has ingested the drug.
Negative test If the drug is not present or is present below the predeter-
mined cutoff for positive test, the r eport is returned as “not
detected.”
Note: A negative result does not necessarily mean the drug
was never taken; it may have been eliminated by the time the
test was taken or may have been present below the assay’s
detection limit. Dilution of urine and rapid drug metabolism
both cause false-negative results. It is also possible that the
drug taken was not included in the drug screening panel
requested.
Interfering factors Amphetamines: False-positive results may occur with ari-
piprazole, atomoxetine, bupropion, ephedrine, labetalol,
MDMA (3,4-methyl enedioxy methamphetamine), phenter
-
mine, pseudoephedrine, ranitidine, selegiline, trazodone,
and Vicks inhalers.
Benzodiazepines: False-positive results may occur with efa-
virenz and sertraline.
Opioids: False-positive results may occur with dextrometho-
rphan, diphenhydramine, rifampin, quinolone antibiotics,
and poppy seeds.
PCP: False-positive results may occur with dextrometho-
rphan, doxylamine, ketamine, tramadol, and venlafaxine.
THC: False-positive results may occur with dronabinol,
efavirenz, and nabilone.
Cross-references Blood Alcohol Level
Drug Abuse
ARUP Laboratories: Drug Plasma Half-Life and Urine Detection Window. Salt Lake City, UT, ARUP Lab-
oratories, 2021. Available at:
https://www.aruplab.com/files/resources/pain-management/
DrugAnalytesPlasmaUrine.pdf. Accessed June
2021
Dadiomov D: Laboratory testing for substance use disorders, in Absolute Addiction Psychiatry Review.
Edited by Marienfeld C. Cham, Switzerland, Springer, 2020.
Moeller KE, Lee KC, Kissack JC: Urine drug screening: practical guide for clinicians. Mayo Clin Proc
83:66–76, 2008
Reisfield GM, Bertholf RL: “Practical guide” to urine drug screening clarified. Mayo Clin Proc 83:848–849,
2008
https://t.me/med1917
286 Laboratory Medicine in Psychiatry and Behavioral Science
Urine epithelial cells and epithelial casts
Type of test Component of routine urinalysis
Background and explanation
of test
Three types of epithelial cells appear in urine:
• Renal tubule epithelial cells, which may be seen with nor-
mal sloughing or may indicate renal disease. In acute tu -
bular necrosis, epithelial cells containing large vacuoles
known as bubble cells may be seen. When lipids cross the
glomerulus, oval fat bodies may be seen.
• Bladder or transitional epithelial cells
• Squamous epithelial cells, mostly from the urethra and
vagina
Epithelial casts form from sloughed tubule cells that have
degenerated. These casts are rare.
Relevance to psychiatry and
behavioral science
Epithelial cells or casts are not a commonly encountered ab-
normality in psychiatric practice, although they may be
found in heavy metal poisoning or aspirin overdose.
Preparation of patient See Urinalysis.
Indications Component of routine urinalysis
Reference range Renal tubule epithelial cells: 0–3/hpf
Renal tubule epithelial casts: 0
Squamous epithelial cells are common in normal urine.
Critical value(s) None
Positive test Renal tubule epithelial cells (>3/hpf):
• Acute tubular necrosis
• Acute glomerulonephritis
• Pyelonephritis
• Salicylate overdose
• Impending allograft rejection
• Viral infection (e.g., cytomegalovirus)
• Heavy metal poisoning or other toxins
Epithelial cell casts are also found with exposure to toxic
agents or vir
uses.
Negative test None
Interfering factors None
Cross-references Urinalysis
Fischbach FT, Fischbach MA: A Manual of Laboratory and Diagnostic Tests, 10th Edition. Philadelphia,
PA, Wolters Kluwer Health/Lippincott Williams and Wilkins, 2018
Simerville JA, Maxted WC, Pahira JJ: Urinalysis: a comprehensive review. Am Fam Physician 71:1153–
1162, 2005
Skoberne A, Konieczny A, Schiffer M: Glomerular epithelial cells in the urine: what has to be done to
make them worthwhile?Am J Physiol Renal Physiol 296(2):F230–F241, 2009
https://t.me/med1917
287 Laboratory Tests
Urine glucose
Type of test Component of routine urinalysis
Background and explanation
of test
Most glucose filtered by the glomerulus is reabsorbed in the
proximal convoluted tubule. If blood glucose is high enough
that the tubule’s capacity is exceeded, glucose appears in the
urine, a sign known as glycosuria. This occurs at a blood glu
-
cose level between 160 mg/dL and 180 mg/dL.
Relevance to psychiatry and
behavioral science
Glycosuria occurs in several conditions of interest to psy-
chiatrists and behavioral health clinicians. See Increased Levels
section below.
Preparation of patient See Urinalysis.
Indications Component of routine urinalysis
Reference range Random specimen: negative for glucose
Critical value(s) Urine glucose >1,000 mg/dL (4+) indicates need to check
blood glucose immediately and begin prompt treatment.
Increased levels •
Diabetes mellitus
• Endocrine disease (Cushing’s syndrome, thyrotoxicosis)
• Liver disease
• Pancreatic disease
• TBI
• Stroke
• Impaired tubular reabsorption (Fanconi syndrome, renal
tubular disease)
• Gestational diabetes
Decreased levels Not applicable
Interfering factors False-positive results (usually trace) may be seen with
stress, MI, testing after heavy meal, or testing after IV glu-
cose administration.
Many drugs interfere with this assay.
Cross-references Urinalysis
Fischbach FT, Fischbach MA: A Manual of Laboratory and Diagnostic Tests, 10th Edition. Philadelphia,
PA, Wolters Kluwer Health/Lippincott Williams and Wilkins, 2018
Simerville JA, Maxted WC, Pahira JJ: Urinalysis: a comprehensive review. Am Fam Physician 71:1153–
1162, 2005
https://t.me/med1917
288 Laboratory Medicine in Psychiatry and Behavioral Science
Urine ketones
Type of test Component of routine urinalysis
Background and explanation
of test
Ketones are breakdown products of fats that are formed in
the liver. Normally, ketones are completely metabolized, so
they do not appear in the urine. When carbohydrate metab
-
olism is altered such that fat is preferentially metabolized,
excessive amounts of ketones are formed that do appear in
the urine. Although ketonuria is most closely associated
with diabetes mellitus, it can also occur in nondiabetic indi
-
viduals who are fasting or on a ketogenic diet, after stren-
uous exercise, during acute illness, after certain types of
anesthesia, with fever, with severe stress, or with pregnancy
and lactation.
Relevance to psychiatry and
behavioral science
Ketonuria in a patient with diabetes is an important sign
that diabetes is not controlled and that medication and/or
dietary intervention is needed. Prolonged vomiting or diar
-
rhea in patients with purging behaviors can be associated
with ketonuria. A false-positive result on urine ketone test
-
ing can occur with the use of valproate or phenothiazine
drugs.
Preparation of patient See Urinalysis.
Indications • Component of routine urinalysis
• Screening and monitoring of pregnant patient
• Determining severity of acidosis
• Various uses in patients with diabetes: monitoring ele-
vated glucose in blood and/or urine, switching from
insulin to oral hypoglycemic, monitoring patients tak-
ing oral hypoglycemic agents, distinguishing diabetic
coma from insulin shock
Reference range Negative or <0.2 mg/dL
Critical value(s) >80 mg/dL signifies a large amount of urinary ketones.
Increased levels • Diabetes—in diabetic patients, ketonuria indicates dia-
betes is not controlled and medication and/or dietary
intervention is needed.
• Starvation—in nondiabetic patients, ketonuria indicates
fat metabolism in preference to carbohydrate metabo-
lism.
• Carbohydrate-restricted diet
• Excessive amount of fat in diet
• Renal glycosuria
• Glycogen storage disease
• Prolonged vomiting or diarrhea
• Hyperthyroidism
Decreased levels Not applicable
https://t.me/med1917
289 Laboratory Tests
Urine ketones (continued)
Interfering factors False-negative results can occur if urine is allowed to stand
too long before analysis.
False-positive results can occur with certain drugs: valpro-
ate, phenothiazines, levodopa, aspirin, insulin, metformin,
acetylcysteine, captopril, niacin, isoniazid, phenazopyri
-
dine, penicillamine, and isopropyl alcohol, among others.
Cross-references Diabetes Mellitus
Urinalysis
American Association for Clinical Chemistry: Testing.com. Available at: https://www.testing.com. Ac-
cessed October 2021.
Fischbach FT, Fischbach MA: A Manual of Laboratory and Diagnostic Tests, 10th Edition. Philadelphia,
PA, Wolters Kluwer Health/Lippincott Williams and Wilkins, 2018
Simerville JA, Maxted WC, Pahira JJ: Urinalysis: a comprehensive review. Am Fam Physician 71:1153–
1162, 2005
https://t.me/med1917
290 Laboratory Medicine in Psychiatry and Behavioral Science
Urine leukocyte esterase
Type of test Component of routine urinalysis
Background and explanation
of test
Urine dipstick testing detects the enzyme esterase that is re-
leased by leukocytes (WBCs). Positive results on dipstick
analysis for leukocyte esterase (LE) should be followed up
with a microscopic exam to look for WBCs and bacteria.
Positive results on both nitrite and LE are highly suggestive
of urinary tract infection (UTI) and should be followed up
with a urine culture.
Relevance to psychiatry and
behavioral science
Testing for LE is helpful in the detection of a UTI, which can
be associated with delirium and other mental status
changes, particularly in elderly patients.
Preparation of patient See Urinalysis.
Indications • Component of routine urinalysis
• Clinical suspicion of UTI
Reference range Negative for LE
Critical value(s) None
Positive test • Cystitis (bladder infection)
• Acute pyelonephritis
• Acute nephritis
• Bladder tumor
• SLE
• Tuberculosis
Negative test UTI is not likely present. Unless other evidence of a UTI is
found, microscopic exam and culture are not indicated.
Interfering factors False-positive results can occur with vaginal discharge, par-
asites, certain drugs (e.g., ampicillin, kanamycin), salicylate
toxicity, or strenuous exercise.
False-negative results can occur with large amounts of glu-
cose or protein in the urine, high urine specific gravity, or
certain drugs (e.g., tetracycline).
Cross-references Urinalysis
Urinary Tract Infection
Urine Dipstick Testing
American Association for Clinical Chemistry: Testing.com. Available at: https://www.testing.com. Ac-
cessed October 2021.
Fischbach FT, Fischbach MA: A Manual of Laboratory and Diagnostic Tests, 10th Edition. Philadelphia,
PA, Wolters Kluwer Health/Lippincott Williams and Wilkins, 2018
Simerville JA, Maxted WC, Pahira JJ: Urinalysis: a comprehensive review. Am Fam Physician 71:1153–
1162, 2005
https://t.me/med1917
291 Laboratory Tests
Urine microalbumin
Type of test Urine (random “spot” specimen or 24-hour collection)
Background and explanation
of test
A normally functioning kidney does not allow albumin or
other proteins to pass into the urine, so the presence of al
-
bumin in a urine sample signals dysfunction of the glomer-
ular filtration barrier. This albuminuria is now understood
to reflect not only kidney disease but also risk of cardiovas
-
cular disease and vascular retinopathy. Microalbumin-
uria—now termed moderately increased albuminuria—is
defined by an albumin excretion of 30–300 mg in a 24-hour
urine collection. Macroalbuminuria or proteinuria—now
termed severely increased albuminuria—is defined by an albu-
min excretion >300 mg in 24 hours.
Individuals at risk of albuminuria include those with
known kidney disease, diabetes, hypertension, obesity, or
family history of chronic kidney disease. Those who are el
-
derly or who belong to certain racial or ethnic groups also
are at risk.
The definitive test for urine albumin requires a 24-hour
urine sample, but screening is usually done with a first-void
morning urine specimen for which both albumin and creat
-
inine are measured, and the albumin-to-creatinine ratio is
determined. The urine dipstick has been considered an in
-
sensitive marker for albuminuria.
Relevance to psychiatry and
behavioral science
Urine microalbumin has been underutilized for patients
treated in behavioral health settings who are diabetic, hy
-
pertensive, or treated chronically with analgesic drugs.
Preparation of patient Heavy exercise should be avoided before and during the
24-hour urine collection. Urine should not be collected
during menstruation because blood contamination invali
-
dates the results.
Indications Detection of protein on urine dipstick testing
Routine screening indicated for patients with the following
conditions:
• Diabetes (testing every 12 months)
• Hypertension
• Family history of kidney disease
•
Extensive analgesic use (including acetaminophen, as-
pirin, ibuprofen, and other NSAIDs)
Reference range 24-hour urine: <15 mg/24 hours
Spot urine: <10 mg/L
Albumin-to-creatinine ratio:
•Males <10 mg/g
•Females <15 mg/g
Critical value(s) Moderately increased albuminuria: 30–300 mg/24 hours
Severely increased albuminuria: >300 mg/24 hours
https://t.me/med1917
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