Clinical manifestations — Numerous signs and symptoms have been associated with zinc depletion (table 3). Mild zinc deficiency is associated with depressed immunity, impaired taste and smell, onset of night blindness, and decreased spermatogenesis. Severe zinc deficiency is characterized by severely depressed immune function, frequent infections, bullous pustular dermatitis, diarrhea, and alopecia (picture 2) [3,4,50].
In some situations, zinc depletion is documented by measurement of zinc concentration in plasma, lymphocytes, or neutrophils. Because zinc is a cofactor for alkaline phosphatase activity, alkaline phosphatase serves as a serologic marker for zinc depletion [51]. In other situations, the diagnosis of zinc depletion is inferred by the response to zinc supplementation in placebo-controlled intervention. (See 'Zinc supplementation' below