Zinc is an oligo-element (essential element required in very small quantities). Zinc comes from diet and is essential for the proper functioning of several biological processes. Zinc levels can be measured in blood and, especially in cases of industrial poisoning, in the urine and hair. Blood zinc levels are expressed in micromoles per litre (µmol/L).
In general, abnormally low levels indicate a zinc deficiency while abnormally high levels may indicate excess zinc. Effective treatment of a zinc deficiency or excess zinc should bring zinc levels back to the normal range. Zinc levels can be temporarily high during infections, inflammation and pregnancy. Zinc deficiency can be caused by insufficient dietary intake or intestinal absorption, loss through the kidneys or increased body needs. Symptoms of zinc deficiency include developmental delays, hair loss, diarrhea, weakness, eye and skin problems, and loss of appetite. Outside an industrial environment, excess zinc is rare. It may be accompanied by nausea, vomiting and diarrhea. In the long term, high zinc levels can impair copper absorption and cause anemia or interfere with immune response.