Radioreceptorassay for human growth hormone in serum

Radioreceptorassay (RRA) for serum human growth hormone (hGH) using late pregnancy rabbit liver receptors is reported. The sensitivity was 90 +/- 11 pg per tube with high specificity and without cross-reactivity with other human pituitary hormones except prolactin (2.4% cross-reactivity). Accuracy of the assay was good and dilution curve of acromegalic serum parallel with standard curve. The coefficients of variation for intra- and inter-assay were 11.3-13.3 and 7.7-18.8%, respectively. The mean concentration of RRA hGH in 64 normal adults was 1.2 +/- 0.3 ng/ml. The level of RRA hGH was less than 1 ng/ml in 57 of 64 normal controls, while that of RRA hGH in 23 acromegalic sera was 98.7 +/- 33.7 ng/ml, the difference being highly significant (P less than 0.01). Thus, RRA hGH is a good index reflecting functional state of hGH.