68: Prolactin response to TRH in children with hypopituitarism

Abstract

Prolactin (PR) and TSH responses to IV TRH (0.2 mg/m2) were studied in 49 hGH deficient children (33 boys, 16 girls): 29 tumoral hypopituitarisms (TH) including 20 craniopharyngioma (5 before and 15 after surgery) and 20 idiopathic hypopituitarisms (IH). Results were expressed as ng/ml of NIH hPR F3. In IH, the mean PR basal value was 19.8 (range from non detectable ND to 60); 5 values were above the 95 th. percentile of normal range; the mean peak value was 41.6 (range 5 - 114, 6 values were under the 5 th. percentile). In CP, the mean PR basal value was 6.9 (range ND - 16) and the mean peak value was 15.8 (range ND - 33, 12 values under the 5 th. percentile). In other TH, the mean basal value was 21.9 (range 3 -55) and the mean peak value was 42 (range 9 - 90, 3 values under the 5 th. and 3 values above the 95 th. percentiles). In both groups no correlation was found between PR responses and TSH responses or thyroxine (T4) levels. However, in IH normal or high PR responses were always associated with normal or high TSH responses, while low T4 levels were encountered in 7 subjects of this subgroup. In CP, low PR responses with low TSH responses and low T4 levels were observed only after surgical removal. These data demonstrated that PR response to TRH is normal in about 50 % of hGH deficient children, while low responses are frequently observed in CP before and after surgery. Elevated basal and peak levels in some IH or TH lead to speculate a prolactostatin (PIF) deficiency.