Chlorides Normal Values ¾ 110–250 mEq/24 hours ¾ 10–20 g NaCl/24 hours. Vary widely with intake amount and perspiration. The test findings have meaning only in relation to salt intake
1. Acute porphyria: Urine darkens on exposure to sunlight.
Positive porphobilinogen test. Spectroscopic and
2. Cutaneous porphyria: Red urine. Spectroscopic and
Many amino acids react with ferric chloride to give
distinctive colors. Ferric chloride testing is a screening test
not only for aminoacidurias but also for many abnormal
metabolites and drug excretion products. Definitive
Method: Add 10% (w/v) of Ferric chloride solution to
1–2 mL of freshly voided urine. Document color change.
α-Ketobutyric acid Purple, fading to red brown
Homogentisic acid (alkaptonuria) Rapidly fading blue or green
Valine, leucine, and isoleucine
0.2—0.5 g/24 h on purine free diet up to 2.0 g/24 h on high
Uric acid formation occurs as a result of the metabolic
breakdown of nucleic acids, purines are the main sources
of this breakdown. The test is required in the investigation
of metabolic disturbances to identify gout and diagnose
kidney disease. It also reflects the effect of uricosuric
agents when these drugs are used, by indicating the total
amount of uric acid excreted. A 24-hour sample is needed.
Method: Use routine serum biochemical methods for
¾ Cytotoxic drugs used to treat lymphoma and leukemia
often cause greatly increased urinary uric acid levels
¾ High uric acid concentration plus low urine pH may
lead to uric acid stones in the urinary tract.
Found in kidney disease (chronic glomerulonephritis)
because hampered renal function diminishes uric acid
• Chronic alcohol consumption.
2. X-ray contrast media can markedly increase uric acid
3. Many other drugs can also influence these results.
(Catecholamines or 3-Methoxy-4-Hydroxymandelic acid)
Norepinephrine 100–230 mg/24 h
Normetanephrine 12–288 mg/24 h
These investigations for adrenal medullary function are
usually needed for a person with hypertension suspected
to be having pheochromocytoma (a tumor of chromaffin
cells of the adrenal medulla). Incidence is about 1% among
hypertensives. The compounds mentioned above contain
a catechol nucleus and an amine group and are, therefore,
called catecholamines. The major portion of the hormones
is changed into metabolites, mainly 3-methoxy-4-hydroxy
Catecholamines are adsorbed from untreated urine on to
a column of Amberlite IRC 50, eluted and condensed in
alkaline solution with ethylenediamine and the resulting
fluorescence read. However, spectrophotometric methods
are less subject to drug interference than fluorimetry.
Samples should be collected in 10 mL hydrochloric acid
1. High levels found in pheochromocytoma
2. Mild to moderate elevations seen in:
Acetoacetic acid Red or red-brown
Melanin Gray, changing to black
intestinal stasis, malabsorption)
Aspirin, salicylates Stable red-wine color
Phenothiazine derivatives Immediate purple pink
p-Aminosalicylic acid (PAS) Red-brown
86 Concise Book of Medical Laboratory Technology: Methods and Interpretations ¾ Ganglioneuromas
¾ Progressive muscular dystrophy
Increased VMA Levels are Caused by
1. Starvation (patients on nil orally: THerapy should not
2. Foods: Tea, coffee, cocoa, vanilla, gelatin foods,
fruit juice, chocolate, fruit, especially bananas, cider
vinegar, salad dresssing, carbonated drinks, jelly and
jam, candy gum, artificially flavored or colored foods,
3. Drugs causing increased VMA levels:
• Para-aminosalicylic acid (PAS)
False Decreased Levels of VMA are Caused by
¾ Uremia (impairs VMA excretion)
¾ Radiographic contrast agents
Interfering Factors in Determining Catecholamine
¾ Vigorous exercise may increase catecholamine levels
¾ Explain that it is a 24-hour collection test
¾ Explain diet and drug restrictions
¾ Exclude all restricted foods for at least 3 days before test
¾ Exclude all drug intake for 3 to 7 days before the test date
¾ Rest and adequate food and fluids are encouraged, and
stress is to be avoided during the test
¾ Patients can resume all restricted foods, drugs, and
activity as soon as test is completed.
17-ketosteroids (17-KS)17-Ketogenic Steroids
(17–KGS) 17-Hydroxycorticosteroids (17-OHCS)
17-hydroxycorticosteroids: Up to 10 mg/24 h.
The above mentioned substances are urinary steroids
and their estimation is indicated in investigation of
endocrine disturbances of the adrenals and testes.
17-ketosteroids have 19 carbon atoms with a ketone
group at C-17. These steroids are composed of adrenal
hormones and metabolites of testicular androgens. In
men, the adrenals produce 2/3rd of these hormones, while
the testes produce the remainder. In women, the adrenals
17-ketogenic steroids are composed of glucocorticoid
derivatives and pregnanediol, have 21 carbon atoms and
a hydroxyl group at C-17. Their estimation gives a good
reflection of adrenal cortex activity.
17-hydroxycorticosteroids have 21 carbons with
hydroxy groups at C-17 and C-21 and a ketone at C-20.
These are also known as Porter-Silber chromogens.
Their assessment is a colorimetric assay. Urine is subjected
to acid hydrolysis and the steroids are extracted with
ethylene dichloride. A solvent aliquot is evaporated to
dryness under a nitrogen stream and the resultant residue
is reacted with m-dinitrobenzene (Zimmerman reaction),
which in the presence of alkali gives a red color with
compounds containing an active methylene group. This
color obtained has an absorption maximum at 520 µ.
Porter-Silber reaction: The glucuronide conjugates of urinary
corticosteroids are hydrolyzed with β-glucuronidase. The
“freed” steroids and free steroids (i.e. tetra and dihydro
derivatives) normally present in the urine are extracted in
methylene chloride. This extract is washed with a dilute
aqueous alkali to remove a considerable amount of blank
material which consists of estrogens, bile acids and other
interfering chromogens. A portion of methylene chloride
is shaken with a phenylhydrazine hydrochloride—sulfuric
acid—ethanol reagent. For correction of the residual blank
material, another portion of the extract is shaken with just the
ethanol sulfuric acid reagent. The upper layer of methylene
chloride is removed, and the lower phase after color
development is measured spectrophotometrically at 410 nm.
No need to add preservative for 24 hours urine collection for
17-OHCS, but stop all medication 2–3 days prior to test day.
Other methods available are based upon ELISA
¾ There is decrease in 17-KGS and 17-KS excretion
in Addison’s disease, hypopituitarism, Simmond’s
¾ There is an increase in 17-KGS excretion in precocious
puberty because of adrenal hyperplasia, surgery,
excessive burns and infection.
¾ Increased 17-OHCS and 17-KGS usually imply
hyperplasia of the adrenal cortex, tumor, cancer, or
some variation of the adrenogenital syndrome.
¾ Steroid levels are also enhanced in Cushing’s syndrome,
eclampsia, acute pancreatitis, and ACTH therapy. If
the beta-alpha ratio is >0.4, it is indicative of adrenal
carcinoma. Unless the 17-KS are increased, the betaalpha ratio is not likely to be abnormal.
a. Severe stress will cause increased levels of KS and KGS
b. KS levels are often increased in third trimester of
Vary widely with intake amount and perspiration. The
test findings have meaning only in relation to salt intake
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