Extraction and Radioimmunoassay of Growth Hormone in Human Serum

Abstract

A previously described radioimmunoprecipitation assay for human growth hormone has been further developed and the sensitivity has been increased. As little as 0.2 mμg growth hormone can now be detected. Growth hormone has been extracted free of serum interfering substances by an IRC-50 chromatographic procedure. With this method, no human growth hormone was detectable in animal serum and serum from some hypophysectomized subjects. The activity of human serum extracts could be removed by absorption of the serum with anti-human growth hormone serum before extraction. Recovery of human growth hormone added before extraction to human or animal serum averaged 88.3 %. The following growth hormone levels were obtained: normal children and adults, 2.0–7.8 mμg/ml; active acromegaly, 9.1–59.0 mμg/ml; hypopituitary and hypophysectomized subjects, 0–4.6 mμg/ml; nonpituitary dwarfism, 2.3–10 mμg/ml.