The natural history of partial growth hormone deficiency in adults: a prospective study on the cardiovascular risk and atherosclerosis.

BACKGROUND

Partial GH deficiency (GHD) in adults is poorly studied.

OBJECTIVE

The objective of the study was to investigate the natural history and clinical implications of partial GHD.

STUDY DESIGN

This was an analytical, observational, prospective, case-control study.

PATIENTS

Twenty-seven hypopituitary patients (15 women, ages 20-60 yr) and 27 controls participated in the study.

MAIN OUTCOME MEASURES

Measures included GH peak after GHRH plus arginine [(GHRH+ARG), measured by immunoradiometric assay]; IGF-I (measured after ethanol extraction) z-sd score (SDS); glucose, insulin, total cholesterol, high-density lipoprotein (HDL) cholesterol, and triglyceride levels; and common carotid arteries intima-media thickness (IMT) measured periodically.

RESULTS

At study entry, partial GHD patients had significantly lower IGF-I and HDL-cholesterol levels and homeostasis model assessment index than controls. During the 60 months of median follow-up, 11 patients had severe GHD (40.7%), seven normalized their GH response (25.9%), and nine showed persistently partial GHD (33.3%). Patients with developed severe GHD at baseline had similar age and body mass index and lower GH peak (11.5 +/- 1.8 vs. 14.3 +/- 1.5 and 12.8 +/- 1.1 microg/liter, P = 0.008) and IGF-I SDS (-0.88 +/- 0.48 vs. 0.15 +/- 0.58 and -0.42 +/- 0.78; P = 0.01) than the patients with normal GH secretion or partial GHD. Severe GHD was accompanied by decreased IGF-I SDS and increased total to HDL cholesterol ratio, triglycerides, homeostasis model assessment index, and carotid intima-media thickness; normalization of GH secretion was accompanied by increased IGF-I SDS. By receiving-operator characteristic analysis, predictors of severe GHD were a baseline GH peak after GHRH+ARG of 11.5 microg/liter (sensitivity 64%, specificity 94%) and a baseline IGF-I SDS of -0.28 (sensitivity 91%, specificity 63%).

CONCLUSIONS

Of 27 patients with partial GHD after pituitary surgery, 40.7% developed severe GHD and 25.9% normalized their GH response. With the assay used, changes in the GH peak response to GHRH+ARG were accompanied by changes in the IGF-I SDS, metabolic profile, and carotid IMT. A peak GH of 11.5 microg/liter or less and IGF-I SDS -0.28 or less were highly predictive of delayed deterioration of GH secretion.