ELEVATED SERUM PROLACTIN CONCENTRATIONS IN PHENYLKETONURIC PATIENTS ON A LOOSE DIET

OBJECTIVE High levels of phenylalanine (Phe) have been shown to reduce dopamine (DA) and noradrenaline (NA) production, We have therefore ev aluated whether increased serum Phe concentrations lead to increased p rolactin (PRL) secretion in phenylketonuria. PATIENTS Forty-two patien ts with classical phenylketonuria were divided into two groups. Group A (n = 19) adhered very strictly to their special diet (Phe = 0.09 +/- 0.039 mmol/l) and Group B (n = 23) were on a 'loose diet' (Phe = 0.77 +/- 0.45 mmol/l). Thirty healthy children of comparable age served as controls. MEASUREMENTS PRL was measured by RIA, and Phe and tyrosine (Tyr) with an amino-acid autoanalyser. Adrenaline (A), noradrenaline ( NA), and dopamine (DA) were measured by HPLC. RESULTS Serum PRL in gro up B patients (1595 +/- 57 mU/l) was significantly raised compared to Group A patients (243 +/- 57 mU/l) and controls (201 +/- 55 mU/l) (P < 0.001). Serum DA, A and NA in group a were lower than in group A pati ents and controls. Serum Phe in group B patients was significantly cor related to serum PRL (r = 0.59) and DA (r = -0.41). Irregular menses w ere observed in 1/10 women from group A but in 10/13 in group B. CONCL USION High serum phenylalanine concentrations in phenylketonuric patie nts not strictly adhering to their diets are correlated with high seru m PRL and low serum dopamine concentrations, and a high prevalence of menstrual irregularities.