Clinical usefulness of urinary growth hormone measurements in normal and short children according to different expressions of urinary growth hormone data

Abstract

To assess the clinical usefulness of urinary growth hormone (UGH) measurements, a UGH determination technique, including dialysis, ultrafiltration, and measurement by polyclonal-coated tube RIA, was established. Sixty-three short children were studied: 56 idiopathic growth retarded (37 prepubertal and 19 pubertal) and seven prepubertal with classic GH (growth hormone) deficiency. Forty-two healthy children (32 prepubertal and 10 pubertal) served as controls. Two groups of adults were studied: eight with active acromegaly and 11 healthy controls. UGH was measured in 24-h urine samples from all patients and controls. Mean ± SD UGH excretion expressed as ng/24 h was significantly lower in the GH-deficient group compared with prepubertal growth-retarded and control children (p < 0.01). No differences were found between UGH excreted by controls and by the growth-retarded groups. Pubertal children excreted significantly higher amounts of GH when UGH was expressed as ng/24 h (p < 0.02 and p < 0.03, respectively), but this difference disappeared when UGH was expressed as ng/g creatinine. UGH was significantly higher in acromegalic patients compared with adult controls (p < 0.001). Differences between day, night, and 24-h UGH were studied in 23 children. UGH in night urine was significantly lower whether expressed as the total amount or as ng/g creatinine. The effect of recombinant hGH administration on UGH was studied in 13 children after 6 and 12 mo of treatment. UGH increased significantly under recombinant hGH treatment. An endogenous GH secretion study was performed in 41 children: UGH expressed as ng/24 h correlated significantly with mean serum 24-h GH, IGF-I concentration, chronologic age, and growth velocity, whereas when expressed as ng/g creatinine, UGH correlated only with mean serum 24-h GH and growth velocity. In conclusion, UGH determination is a noninvasive, easily repeatable way of assessing GH secretion. UGH expressed as the total amount per 24 h would appear to be a more advantageous approach to the expression of UGH data for clinical purposes. © 1992 International Pediatric Research Foundation, Inc.