Serum alkaline phosphatase and zinc undernutrition in infants with chronic diarrhea.

III infants and children need zinc replacement in total parenteral nutrition solutions, but assessment of these needs and total body zinc status is difficult. Seven infants with severe diarrhea initially given 80 to 100 micrograms/kg/day of elemental zinc developed systemic zinc deficiency as indicated by an acrodermatitis-like skin rash and low serum alkaline phosphatase. Serum zinc levels were borderline low only in conjunction with hypoalbuminemia. Daily urinary zinc excretion was normal. With increased zinc supplementation of 200 to 300 micrograms/kg/day, the rash healed and serum alkaline phosphatase rose to normal levels for age. The activity of the metalloenzyme alkaline phosphatase accurately reflects total body zinc status in infants. With diarrheal illness, infants, need high doses zinc supplementation to replace considerable stool losses.