Limited effects of growth hormone replacement in patients with GH deficiency during long-term cure of acromegaly

The aim of this study was to assess the effects of replacement with recombinant human growth hormone (rhGH) in patients with GH deficiency (GHD) after treatment of acromegaly. Intervention study. Sixteen patients (8 men, age 56 years), treated for acromegaly by surgery and radiotherapy, with an insufficient GH response to insulin-induced hypoglycaemia, were treated with 1 year of rhGH replacement. Study parameters were assessed at baseline and after 1 year of rhGH replacement. Study parameters were cardiac function, body composition, bone mineral density (BMD), fasting lipids, glucose, bone turnover markers, and Quality of Life (QoL). During rhGH replacement IGF-I concentrations increased from −0.4 ± 0.7 to 1.0 ± 1.5 SD (P = 0.001), with a mean daily dose of 0.2 ± 0.1 mg in men and 0.3 ± 0.2 mg in women. Nonetheless, rhGH replacement did not alter cardiac function, lipid and glucose concentrations, body composition or QoL. Bone turnover markers (PINP and β crosslaps) levels increased (P = 0.005 and P = 0.021, respectively), paralleled by a small, but significant decrease in BMD of the hip. The beneficial effects of rhGH replacement in patients with GHD during cure from acromegaly are limited in this study

Advantages of IRMA over RIA in the Measurement of ACTH

A technically simple and rapid two-site immunoradiometric assay (IRMA) for human ACTH, based on monoclonal antibodies (MAbs), was compared with a clinically validated ACTH radioimmunoassay (RIA). Both methods measure ACTH 1-39 in unextracted plasma and cross-react <0.5% with ACTH fragments. ACTH levels were assessed in 103 patient samples: for concentrations in the range 5.3-1000 ng/L, results by the two methods were significantly correlated (r = 0.82, n = 86, P <0.001). The IRMA was more sensitive and had a wider working range than the RIA (detection limits 5.3 ng/L (IRMA) vs 11 ng/L (RIA); CV <10% between 19 and 1000 ng/L (IRMA) and CV <15% between 30 and 400 ng/L (RIA)). In two patients for whom discrepant results were obtained, measurement of ACTH by bioassay and ACTH precursors by direct IRMA demonstrated the greater accuracy of the ACTH IRMA result. The improved performance of the IRMA combined with its many practical advantages compared to RIA, make it ideal for use in detailed clinical and physiological studies which have previously been hampered by the poor reliability of ACTH measurement