Explain the Assessment of Zn Status?

Sensitive indices for assessing zinc status are unknown at present. Static indices, such as zinc concentration in plasma, blood cells and hair, and urinary zinc excretion are decreased in severe zinc deficiency. A number of conditions that are unrelated to zinc status can affect all these indices, especially zinc plasma levels. Food intake, stress situations such as fever, infection and pregnancy lower plasma zinc concentrations whereas, for example, long term fasting increases it. However, on a population basis, reduced plasma zinc concentrations seem to be a marker for zinc- responsive growth reductions. A number of functional indices of zinc status have also been suggested, for example, wound healing, taste acuity and visual adaptation to the dark. Changes in these functions are, however, not specific to zinc and these indices have not been proven useful for identifying marginal zinc deficiency in humans thus far.