Zinc

Bluish-white metal which plays a role in dermatology in zinc deficiency dermatoses. Furthermore, zinc in the form of zinc oxide is used as a component of powders, shaking mixtures, oils(zinc oil) or pastes(zinc paste) with different indications.

Standard values: The reference range in serum and plasma is between 9 and 21 µmol/l, in whole blood between 60 and 115 µmol/l

Pathologically debilitated: alcoholism, diabetes mellitus, infections, chronic liver diseases, nephrotic syndrome, malnutrition, malassimilation, acrodermatitis enteropathica, rheumatic diseases

Pathologically increased: excessive zinc supply

Zinc assumes catalytic, structural and regulatory functions in the body.

There are 2 groups of carrier proteins that regulate the transmembrane transport of zinc: ZnT and Zip. ZnT transporters reduce intracellular zinc levels by being responsible for direct excretion or uptake into intracellular vesicles. Zip transporters cause zinc to flow from the aforementioned reservoir into the cells. Depending on the zinc supply, these zinc transporters are expressed at different levels.

The absorption of zinc occurs in the jejunum. The zinc content in serum is 70 µg/dL, values < 40 µg/dL indicate a zinc deficiency. Strong fluctuations are known, partly depending on the food intake.

The incidence of inherited zinc deficiency worldwide is 1/500,000 inhabitants.

Zinc sources in food are 33% meat and meat products, 25% milk, dairy products and eggs, 20% cereal products and 20% other sources.

Dietary zinc deficiency is a rarity, affecting developing countries and strict vegetarians.

In acrodermatitis enteropathica, the congenital, autosomal-recessive inherited primary zinc absorption disorder (gene locus 8q24.3) is discussed, caused by the absence of a zinc binding factor (Soluble Carrier SLC39A4) in the small intestine, which is present in breast milk but not in cow's milk and leads to a decrease in zinc absorption to 2-3% of normal levels.

1. Maverakis et al (2007) Acrodermatitis enteropathica and an overview of zinc metabolism. J Am Acad Dermatol 56: 116-124