Biological activity of luteinizing hormone in uraemic children: spontaneous nocturnal secretion and changes after administration of exogenous pulsatile luteinizing hormone-releasing hormone--preliminary observations.

Normal pubertal progression is associated with quantitative and qualitative changes in gonadotrophin release. Uraemic children show a delayed or disturbed puberty. We have therefore examined nocturnal gonadotrophin and sex steroid secretion in seven males and three females [age 11-15 years, pubertal stage (PS) 1-3] with chronic renal failure on conservative treatment. In addition to immunoreactive luteinizing hormone (i-LH) we have measured the biological activity of LH (b-LH). Nine children aged 12-17 years with PS 1-3 and normal renal function served as a control group. In two uraemic children, i-LH, b-LH, follicle stimulating hormone and sex steroids were evaluated before and 7 days after pulsatile LH-releasing hormone (LHRH) administration (150 ng/kg body weight subcutaneously every 120 min). Mean i-LH levels were higher in uraemic children than in controls. An increase in i-LH during sleep was found in all controls and in eight of ten uraemic subjects. Mean b-LH levels were lower during sleep and the b/i LH ratio was reduced in uraemic children with PS 2-3 whether asleep or awake compared with controls. Pulsatile administration of LHRH provoked a rise of i-LH and b-LH levels with an increased b/i LH ratio, suggesting an intact pituitary responsiveness. These preliminary data indicate that the gonadotrophin control of LH is abnormal in uraemic children, and that biopotency of LH secretion might be improved after short-term pulsatile LHRH administration.