Zinc is an essential trace element integrally involved in a wide range of metabolic processes required for tissue growth and repair as well as being necessary for maintaining host defences. Zinc deficiency can occur from lack of adequate dietary intake, decreased intestinal absorption, and increased losses in the gastrointestinal tract, urine, and sweat. The clinical signs of zinc deficiency can present in a florid manner with dermatitis, alopecia, and diarrhea, or they can be chronic changes with dwarfism and hypogonadism or, the signs may be barely perceptible with low growth rates and hypogeusia. As with all nutritional deficiencies, the possibility of its existence must be considered before the diagnosis can be made. It is not known how severe zinc deficiency must be or how long it has to be present before the characteristic rash appears. However, as biochemical changes of zinc deficiency occur before any clinical changes do, it is likely that metabolic processes have been affected before the rash heralds the presence of zinc deficiency.
Pediatr. Clin. North Am. 1983 Jun;30(3):583-96