The impact of gender and puberty on reference values for urinary growth hormone excretion: a study of 3 morning urine samples in 517 healthy children and adults

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Some recent studies have indicated that measurement of urinary GH (U-GH) excretion may be a useful tool for the evaluation of GH insufficiency in children with growth disorders, although some investigators are skeptical about the diagnostic value of U-GH. Most current assays are only available for specific laboratories or require time-intensive pretreatments of the specimens. This limits the possibility for many centers to compare their patients' data with others or to establish their own reference ranges for U-GH excretion. Therefore, we investigated the performance of a commercially available kit, which allows direct measurement of U-GH in untreated urine specimens. We established a reference range for the geometric mean of 3 morning urine samples in 446 healthy children and 71 adults. U-GH could be determined in all but 9 of 1526 samples (99.4%). U-GH excretion was significantly dependent on pubertal maturation (P <0.001) and sex (P <0.001), whereas age had no significant influence in the prepubertal group (P > 0.3). Peak values occurred in Tanner stages 3 and 4 (369 and 391 pg/h in females; 503 and 882 pg/h in males), corresponding to an age interval of 11-18 yr in boys and 9-15 yr in girls. Short collection periods (<6 h) were related to low values for U-GH excretion (nanograms per night; P <0.02). This time effect disappeared if U-GH excretion was expressed as picograms per h. If U-GH was related to creatinine output, there was a decrease in U-GH excretion during prepuberty, a blunting of the pubertal peak, and lower values in adults than in prepubertal children (P <0.0002). The intraindividual variation in U-GH excretion (picograms per h) ranged from 40-61%, constituting approximately two thirds of the interindividual variation. This variation was not lowered by relating U-GH to creatinine. We conclude that the assay was suitable for measurement of U-GH excretion in virtually all healthy volunteers. Sex and pubertal stage as well as urinary volume and clock times for collection periods should be registered when establishing a reference range for U-GH excretion and applying it for clinical purposes. Our reference values may be useful for further studies of patients with GH disorders.
Original languageEnglish
JournalJournal of Clinical Endocrinology and Metabolism
Issue number3
Pages (from-to)865-71
Number of pages7
Publication statusPublished - 1994

ID: 48486865