MAUI, HAWAII Consider zinc deficiency when an infant presents with an eczema-like dermatitis limited to the diaper and perioral areas.
"Eczema tends not to affect the diaper area because it's so moist and occluded," Dr. Brandie J. Metz noted at the annual Hawaii dermatology seminar sponsored by Skin Disease Education Foundation.
Zinc deficiency in infants can be inherited, acquired, or caused by malabsorption due to cystic fibrosis or other systemic diseases. All forms of zinc deficiency, however, present with the same clinical picture, including the typical rash, diarrhea, and irritability, explained Dr. Metz, a pediatric dermatologist at the University of California, Irvine.
The perioral part of the rash often occurs in a U-shaped distribution below the mouth. One clue that the perioral and diaper-area dermatitis is not eczema is complete lack of improvement with topical corticosteroids.
Acquired zinc deficiency is caused by abnormal excretion of zinc into breast milk. Affected babies will present while breast feeding and clear a few days after being switched to cow's milk or formula.
In contrast, infants with acrodermatitis enteropathica, the inherited form of zinc deficiency, are fine early on while breast feeding because the zinc in breast milk has good bioavailability. These infants become symptomatic a week or two after weaning from breast milk or at 4-10 weeks of age if they are exclusively breast fed, Dr. Metz continued.
Acrodermatitis enteropathica is a rare autosomal recessive disorder thought to involve a defect in intestinal absorption or zinc transport. It has been linked to the human ZIP4 gene, she noted.
Acquired zinc deficiency can't be diagnosed on the basis of a low maternal plasma zinc level because maternal breast milk zinc levels are independent of maternal blood levels. For the same reason, maternal zinc supplements are ineffective for the treatment of a zinc-deficient baby.
Pediatric plasma zinc levels can be misleadingly normal in children with mild deficiency, particularly if the specimen is contained in a plastic tube or a tube with a rubber stopper, which can leak zinc into the sample, Dr. Metz explained.
SDEF and this news organization are owned by Elsevier.
Acquired zinc deficiency is caused by abnormal excretion of zinc into breast milk. DR. METZ