The effect of treatment on zinc, copper and calcium status in children with phenylketonuria.

The trace element status of 25 children receiving a low phenylalanine diet for a treatment of phenylketonuria was studied using hair and serum samples. Hair trace element and calcium concentrations were assayed using X-ray microanalysis and compared with samples from sibling controls. Plasma, zinc and copper levels were compared with unselected hospital attenders. PKU patients were found to have significantly lower hair zinc (P less than 0.001) and calcium (P less than 0.01) concentrations and significantly hair copper (P less than 0.001) concentrations compared with controls. Plasma zinc levels were below the lower limit of normal (9.6 mumol l-1) in 8 of 19 patients (42%) in whom it was measured. The relative zinc deficiency in PKU patients may result from a competitive inhibition of absorption by copper or other metals supplemented in the diet.