Bioactivity of Human Growth Hormone in Urine from Acromegalic Patients

Abstract
Bioactivity of hGH in urine from five acromegalic patients was determined by Nb2 bioassay and IM-9 receptor modulation assay (RMA). Urine samples were concentrated by immunoadsorbant chromatography, dialysis and lyophilization. The ratio of the bioactivity by Im-9 RMA and the immunoactivity by RIA was between 0.81 and 1.24(1.01 ± 0.19, mean ± SD). The ratio of the bioactivity by Nb2 bioassay and the immunoactivity ranged from 0.45 to 0.60 (1.37 ± 0.85). Gel chromatography of hGH in urine samples measured by sensitive sandwich enzyme immunoassay showed that more than 97% of hGH activity was the 22K form. Urinary hGH from acromegalic patients was bioactive in Nb2 bioassay and IM-9 RMA and the bioactivity showed a close correlation with the immunoactivity. The major immunoactive form of hGH (22K) seems to correspond to the bioactivity.

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