Infradian rhythms in urinary growth hormone excretion

Nandu K S Thalange, Matthew S. Gill, Len Gill, Andrew J. Whatmore, G. Michael Addison, D. Anthony Price, Peter E. Clayton

    Research output: Contribution to journalArticlepeer-review

    Abstract

    All studies of urinary GH excretion in normal and disordered growth have revealed marked day to day (infradian) variation. We used serial overnight urinary GH estimations as an indirect measure of endogenous GH secretion in eight normal prepubertal children (aged 3.6-7.3 yr) over 90-365 days to determine whether longer term rhythms in GH output could exist. This study constitutes a first step in examining the potential relationship between GH excretion and growth. Urinary GH was measured by immunoradiometric assay after dialysis, expressed as the total amount excreted (nanograms per night) or as the GH/creatinine ratio (nanograms per mmol), and assessed by pulse counting techniques and time-series analysis. Variability in urinary GH excretion (median coefficient of variation, 16%) was significantly greater than creatinine (median coefficient of variation, 25%; P = 0.003). Additionally, there was marked month by month variation in baseline urinary GH in all children. High frequency pulses of urinary GH were defined in all children, with periods between 3-5 days. In the two children followed for 7 months or more, time-series analysis was also undertaken on urinary GH data divided into weekly series. This revealed significant rhythms present at 2.6 and 4.1 weeks. There were, therefore, three components to urinary GH excretion: long term basal fluctuation (over months), short term pulses (over days), and intermediate rhythms (over weeks). Further work is required to establish the relationship between these patterns of GH excretion and short term growth.

    Original languageEnglish
    Pages (from-to)100-106
    Number of pages7
    JournalJournal of Clinical Endocrinology and Metabolism
    Volume81
    Issue number1
    DOIs
    Publication statusPublished - 1996

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