Growth Hormone: Metabolic Clearance Rates, Integrated Concentrations, and Production Rates in Normal Adults and the Effect of Prednisone

Abstract

A constant withdrawal pump was used to determine the integrated concentration of growth hormone (ICGH) which was used in conjunction with the metabolic clearance rate (MCR) of growth hormone (GH) to calculate the GH production rates (GHPR) in normal adults, acromegalics, and normal controls receiving prednisone. The mean ICGH for 22 premenopausal females on no medication was 3.0±1.6 ng/ml (sd) which is significantly lower (P < 0.005) than the mean of 6.6±2.9 for 10 women receiving oral contraceptives and significantly higher than the means of 1.5±0.75 for 5 postmenopausal females (P < 0.05) and 1.8±1.0 for 16 adult males (P < 0.01) which are comparable. The mean GHPR's in mg/24 hr per m² for the four groups are: normal females = 0.52±0.24 (sd), females receiving contraceptive pills = 1.65±0.58 (P < 0.005), postmenopausal females = 0.26±0.12 (P < 0.025), and adult males 0.35±0.23 (P < 0.025). Three untreated acromegalic patients had ICGH's of 59, 82, and 93 ng/ml and GHPR's ranging from 14.5 to 17.9 mg/24 hr. Prednisone in a dose of 20 mg t.i.d. for 8 days significantly decreased both the ICGH and GHPR. Alternate day prednisone (60 mg in a single q.o.d. dose) resulted in less consistent inhibition of GH release which may play a role in the more normal growth seen in children receiving q.o.d. prednisone.