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Unit Code 8620:
Zinc, Serum

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Useful For

Detecting zinc deficiency

Clinical Information

Zinc is an essential element; it is a critical co-factor 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 phyate (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 causes excess loss of zinc by enhancing renal

excretion.  Zinc depletion occurs in burn patients who loose zinc in the

exudates from their burn sites.

 

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

0.66-1.10 ug/mL

 

(U for NIH)

66-110 ug/dL

Interpretation

Normal serum zinc is 0.66-1.10 ug/mL.

 

Burn patients with acrodermatiitis may have zinc as low as 0.4 ug/mL;

these patients respond quickly to zinc supplementation.

 

Other diseases that cause low serum zinc are hepatic cirrhosis,

ulcerative colitis, Crohn's disease, regional enteritis, sprue,

intestinal bypass, neoplastic disease, and increased catabolism

induced by anabolic steroids.  The conditions of anorexia and

starvation also result in low zinc levels.

 

Elevated serum zinc is of minimal clinical interest.

Cautions

Hemolyzed specimens will cause false elevation of serum zinc levels.

 

Gadolinium is known to interfere with most metals tests. If gadolinium-

containing contrast media has been administered a specimen can

not be collected for 48 hours.

 

It is essential that the specimen is collected following the trace metals

collection procedure (see "Metals Analysis - Collection and Transport"

in Special Instructions.)

Special Instructions and Forms

• Metals Analysis - Collection and Transport 

Clinical Reference

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

deficiency:  cutaneous manifestations typical of acrodermatitis

enteropathica.  JAMA 1976;235:2399-2402

Key