Clinical use: Testing of zinc can be used to diagnose or rule out zinc deficiency.
Background: 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 inadequate intake or because the zinc in the diet is bound to fibre and not available for absorption. Once absorbed, the most common route of loss is via exudates from open wounds or gastrointestinal loss. Zinc depletion occurs in burn patients who lose zinc in the exudates from their burn sites. Hepatic cirrhosis causes excess loss of zinc by enhancing renal excretion. Other diseases that cause low serum zinc are ulcerative colitis, Crohn’s disease, regional enteritis, intestinal bypass, neoplastic disease, and increased catabolism induced by anabolic steroids. The conditions of anorexia and starvation also result in low zinc levels.

Zinc excess is not of major clinical concern. Excess zinc passes through the gastrointestinal tract and is excreted in the faeces. 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, which can lead to hypocupremia.

Reference ranges: 9.8 – 20.6 umol/L
Associated diseases:
Patient preparation: None required
Specimen requirements: A dark blue topped sample is required for analysis.
Turnaround time: 1 week
Additional information:
Referred test: Referred test
Location: Northern General Hospital NHS Trust