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Unit Code 8591:
Zinc, Urine

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Useful For

Identifying the cause of abnormal serum zinc

Clinical Information

Zinc is an essential element; it is a critical cofactor for carbonic

anhydrase, alkaline phosphatase, RNA and DNA polymerases,

alcohol dehydrogenase, and many other physiologically important

proteins. The peptidases, kinases, and phosphorylases are most

sensitive to zinc depletion.

 

Zinc is a key element required for active wound healing.

 

Zinc depletion occurs either because it is not absorbed from the diet

or it is lost after absorption. Dietary deficiency may be due to absence

(parenteral nutrition) or because the zinc in the diet is bound to fiber and

not available for absorption. Once absorbed, the most common route of

loss is via exudates from open wounds such as 3rd-degree burn or

gastrointestinal loss as in colitis. Hepatic cirrhosis also causes excess

loss of zinc by enhancing renal excretion. The peptidase, kinase, and

phosphorylase enzymes are most sensitive to zinc depletion.

 

Zinc excess is not of major clinical concern. The popular American habit

of taking mega-vitamins (containing huge doses of zinc) produces no

direct toxicity problems. Much of this zinc passes through the gastrointestinal

tract and is excreted in the feces. The excess fraction that is absorbed is

excreted in the urine.

 

The only known effect of excessive zinc ingestion relates to the fact

that zinc interferes with copper absorption that can lead to hypocupremia.

Reference Values

300-600 ug/specimen

Specimens collected for other than a 24-hour time period are reported

in unit of ug/L, for which reference values are not established.

Interpretation

Fecal excretion of zinc is the dominant route of elimination.

 

Renal excretion is a minor, secondary elimination pathway.

 

Normal daily excretion of zinc in the urine is in the range of

300-600 ug/24 hours.

 

High urine zinc associated with low serum zinc may be caused by

hepatic cirrhosis, neoplastic disease, or increased catabolism.

 

High urine zinc with normal or elevated serum zinc indicate a large

dietary source, usually in the form of high-dose vitamins.

 

Low urine zinc with low serum zinc may be caused by diet deficiency

or loss through exudation common in burn patients and those with

gastrointestinal losses.

Cautions

Avoid specimen containers with metal cap liners.

 

High concentrations of gadolinium and iodide are known to interfere

with most metals tests. If either gadolinium or iodide-containing

contrast media has been administered a specimen can not be

collected for 48 hours.

Special Instructions and Forms

• Urine Preservatives 
• Metals Analysis - Collection and Transport 

Clinical Reference

Tucker SB, Schroeter AL, Brown PW Jr, McCall JT:  Acquired zinc

deficency:  cutaneous manifestations typical of acrodermatitis

enteropathica.  JAMA 1976;235:2399-2402

Key