90 DOSE URINARY GROWTH HROMONE (GH) REFLECT PLASMA GROWTH GORMONE LEVELS?

Abstract

In 40 children, a 24 h-plasma GH profile has been compared to urinary GH excretion. Plasma was assayed with a conventional radioimmnunoassay (kit CEA). For urine, a radiometric assay has been developed with a solid-phase goat antibody for immunextraction and a I125 monoclonal antibody for quantification. The assay is insensitive to pH 5-8, NaCl/urea 0.1-0.5 mol and to sample volumes up to 10 ml. The sensitivity of 2 pg in the standard results in a detection limit of 1 pg/ml, if 2.5 ml of urine are used. Coefficients of variation are 10-14% for inter-, and 2.5-3.5% for intra-assay. Plasma GH was expressed as integrated concentration (IC, ng/ml/h) per 24 h or night/day periods, urinary GH as pg per 24 h or night/day and was related to creatinine. 1) Correlations for plasma were: IC 24 h to a) IC night 0.93, b) IC day 0.77. 2) Correlations for urine (± creatinine): 24 h to a) day 0.73, b) night 0.8, 24 h/cr. to a) day/cr. 0.53, b) night/cr. 0.83. 3) Correlations for plasma to urine: Plasma IC 24 h to a) urine 24 h 0.45, b) urine 24 h/cr. 0.60, c) urine night/cr. 0.69. It can thus be concluded that urinary GH reflects plasma levels and a daily GH-production. GH-assays in urine are an additional help for the diagnosis of states of deficiency or excess and for the control of suppressive or stimulating therapies.