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PLASMA IMMUNOREACTIVE GHRH AND SERUM GH CONCENTRATIONS FOLLOWING PULSATILE GHRH 1‐40 ADMINISTRATION IN GH DEFICIENT CHILDREN
Author(s) -
SMITH P. J.,
PRINGLE P. J.,
BROOK C. G. D.,
SCHULSTER D.,
RAFFERTY B.
Publication year - 1987
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1987.tb01179.x
Subject(s) - medicine , endocrinology , pulsatile flow , bolus (digestion) , growth hormone–releasing hormone , hormone , growth hormone , peptide hormone , chemistry
SUMMARY We have studied the clearance from plasma of immunoreactive growth hormone releasing hormone 1‐40 (IR‐GHRH) following intravenous (i.v.) and subcutaneous (s.c.) administration and the relationship between exogenous plasma IR‐GHRH concentrations and GH secretion in five GH insufficient children receiving long term nocturnal pulsatile GHRH 1‐40. The i.v. studies with GHRH 140 1μg/kg demonstrated a distribution half life (t 1/2 ) of 3‐9 (SD 0‐9) min and an elimination t 1/2 of 53‐1 (SD 3‐2) min. In the s.c. studies the elimination phase was similar to the i.v. results but the transit time to the GHRH peak was slower than the i.v. distribuition t 1/2 9‐9 (SD 3‐6) min. These characteristics were maintained during successive pulses of subcutaneous GHRH. The mean IR‐GHRH peaks following s.c. GHRH 1‐40 administration of 1 μg/kg and 2 μg/kg were 37‐ and 18‐fold lower respectively than the mean IR‐GHRH peak observed after the i.v. 1 μg/kg bolus study. A significant correlation was shown between peak plasma IR‐GHRH and serum GH concentrations during the s.c. ( r = 0‐75) but not the i.v. studies. Pulsatile GHRH administration has been shown to stimulate GH secretion and growth acceleration in GH insufficient children. Knowledge of the relationship between GHRH 1^40 absorption from the subcutaneous site and GH secretion is important for the development of an optimal GHRH treatment regimen in GH insufficient children.