2 TYPES OF GROWTH-HORMONE RHYTHM IN BOYS WITH CONSTITUTIONAL SHORT STATURE

The relationship between temporal and quantitative changes in pulsatil e growth hormone (GH) secretion and growth of constitutionally short c hildren (CSS) was studied in 19 prepubertal boys and 4 with early adre narche aged 7.8 to 14 years, Continuous plasma GH monitoring was perfo rmed at 30 minute intervals during 24 hours, The data were analysed by single and serial best fit (BFT) cosinor analysis for rhythm paramete rs and the Pulsar peak detection program for determining pulsatile pro perties, The pulsatile patterns were expressed in mean GH concentratio n, area under the curve, mean pulse area and maximal pulse height but not in the number of pulses, Thirteen out of 23 patterns exhibited sig nificant 24-h compatible rhythms, The studied cohort was divided into two groups, those who exhibited the 24-h circadian rhythm (CIR) and th ose who lacked it (NCIR), Ultradian 2.5-4 h rhythms were observed in a ll patients, The NCIR children were significantly shorter than the CIR group (p=0.017), The CIR boys secreted a significantly higher (p=0.01 ) amount of GH during the 24-h span, most of which was during sleep, O ur data indicate that the magnitude of pulses rather than their number is responsible for the quantitative differences observed between the two groups of boys with CSS, It is suggested that a lack of 24-h rhyth micity and the associated reduced nocturnal pulsatility play a role in the manifestation of short stature.