The use of gelatin capsules for ingestion of formula in dietary treatment of maternal phenylketonuria

Summary

Maternal phenylketonuria (PKU) represents a high risk for birth defects, including mental retardation, in offspring. Thus, it could cancel gains represented by the prevention of PKU-induced mental retardation in the current generation. Effective dietary treatment of maternal PKU pregnancies could avoid this potentially tragic occurrence. However, dietary compliance is often difficult because a necessary component of the diet, medical nutritional formulas, often have an unpleasant taste and odour. We treated the second pregnancy of a phenylketonuric women who had required extended hospitalization during her first pregnancy because of poor formula tolerance, and who had similar difficulty in the second pregnancy. To alleviate this problem, we developed a system whereby she could pack the formula into gelatin capsules for ingestion. Packing and ingestion of 20 capsules required less than 30 minutes three times a day. With capsules her blood phenylalanine level was almost always within the recommended range of 120–360 µmol/L (2–6 mg/dl) and hospitalization was not required. The phenylalanine content of the capsules was easily accommodated by a small reduction in allowable food. Other amino acid levels, including tyrosine and other essential nutrient levels, were normal. We believe that using gelatin capsules for formula ingestion can be very beneficial in the management of maternal PKU pregnancies and could be extended to the dietary treatment of other inborn errors of metabolism.