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Subject: Zinc (Zn)
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Zinc, an essential trace element, is the intrinsic metal component or activating cofactor for more than 70 important enzyme systems, including carbonic anhydrase, the ALPs, dehydrogenases, and carboxypeptidases. It is involved in the regulation of nucleoproteins and the activity of various inflammatory cells and plays a role in growth, tissue repair and wound healing, carbohydrate tolerance, and synthesis of testicular hormones. Zinc intake is closely related to protein intake; as a result, it is an important component of nutritionally related morbidity worldwide. Symptoms attributable to severe zinc depletion include growth failure, primary hypogonadism, skin disease, impaired taste and smell, and impaired immunity and resistance to infection. Subclinical zinc deficiency may significantly increase the incidence of and morbidity and mortality from diarrhea and upper respiratory tract infections. Along with iron, iodine, and vitamin A, zinc deficiency is one of the most important micronutrient deficiencies globally. Several studies have now demonstrated that supplementation of high-risk populations can have substantial health benefits.
Normal range: (see Table 16.89).
Detecting zinc deficiency
Assist in confirming acrodermatitis enteropathica
Evaluate nutritional deficiency
Evaluate possible toxicity
Monitor replacement therapy in individuals with identified deficiencies
Monitor therapy of individuals with Wilson disease
Coronary heart disease
Primary osteosarcoma of the bone
Conditions that decrease albumin
Ulcerative colitis, Crohn disease
Regional enteritis, sprue, intestinal bypass, neoplastic disease
Increased catabolism induced by anabolic steroids
Plasma levels of zinc do not necessarily correlate with tissue levels and do not reliably identify individuals with zinc deficiency. Although plasma levels are generally a good index of zinc status in healthy individuals, these levels are depressed during inflammatory disease states.
Erythrocyte concentrations of zinc may provide a more useful measure of zinc status during acute or chronic inflammation. Several functional indices also can be used to indirectly assess zinc status. Serum superoxide dismutase and erythrocyte alkaline phosphatase activities have been proposed as indirect markers of zinc status, but these tests are not widely available.
The conditions of anorexia and starvation also result in low zinc levels.
Hemolyzed specimens cause false elevation of serum zinc levels.
Specimens should be collected in metal-free specimen containers.
Auranofin, chlorthalidone, corticotropin, oral contraceptives, and penicillamine increase zinc levels.
Anticonvulsants, cisplatin, citrates, corticosteroids, estrogens, interferon, and oral contraceptives decrease zinc levels.