A radiometric assay for human growth hormone (HGH) was developed based on a polyclonal goat anti-HGH antiserum covalently coupled to nonsedimenting polyacrylamid particles. HGH can be specifically immunoextracted from sample volumes of up to 10 ml. Subsequently, bound HGH is identified and quantitatively measured by a ¹²⁵I-labelled monoclonal anti-HGH antibody. The assay is insensitive to plasma proteins from 10 to > 90%, to changing NaCl and urea molarities and to pH ranges from 6 to 8. The sensitivity in the second incubation is 2 pg/tube, corresponding to a maximum sensitivity of 300 fg/ml of a sample volume of 10 ml (urine) or of 40 pg/ml, if a volume of 50 µl (plasma) is assayed. In healthy children, a mean HGH excretion of 6.5 ng/24 h was found with a large interindividual range from undetectable to 37.4 ng. An important intraindividual night-tonight variation of HGH excretion was found in several subsequent first morning void samples in healthy children. The mean excretion in 13 HGH-deficient children was 0.9 ng/24 h off therapy and increased to a mean of 6.9 ng/24 h on therapy. In acromegalic patients, the excreted HGH amounted to 73–208 ng/24 h. Preliminary results suggest that the ultrasensitive assay applied to plasma and urine could be a considerable improvement of diagnosis and follow-up of disorders of HGH secretion.

An immunoradiometric assay for human growth hormone (HGH) has been developed which has a detection limit of 1 ng/l and can measure HGH in unextracted urine from normal children and adults. The assay is based on a two-step procedure, using a solid-phase goat-anti-HGH immunosorbent for immunoextraction and [125I]-labeled monoclonal HGH-antibody for detection and quantification. The assay is not affected by urea, NaCl or changes of pH from 5-8. The mean urine HGH concentration in normal children is 6.78 +/- 7.6 (SD) pg/ml, in patients with HGH-deficiency 1.3 +/- 0.9 pg/ml which increases to 11.7 +/- 13.4 pg/ml on the day of growth hormone injection.

During puberty, growth and circulating SIC increase require normal GH secretion txlt the respective role of GH and sex steroids is still unsettled.This question was adressed by canparing children with low or normal GH secretion &ring PP. 28 children, with PP and similar gonadal activity, were classified into 2 groups according to their GH peak response to AITT : Grcup I > 10 ng/ml, Group I1 < 5 ng/ml. They were carpared to prepubertal hypopituitary cases (Grwp 111). Plasma SmC/IGFI was measured by RIA (m + sem).Group n CA (yr) DA (yr) cm/yr GH peak (ng/ml) SmC (U/ml) I 20 7.1 + 0.5 9.8 20.6 9 + 0.6 24 ~2 . 5 2.01 + 0.17 I1 8 8.2 + 1.1 9.5 + 1.3 6.8 + 0.6 3 50.5 0.71 + 0.14 I11 7 11.3 + 1.1 6.9 20.9 1.9 + 0.5 1 + 0.3 0.07 ~0 . 0 1 Ry canparison of II/I it appears thst GH deficiency decreased the mean SmC level (p