Effects of growth hormone administration on inflammatory and other cardiovascular risk markers in men with growth hormone deficiency. A randomized, controlled clinical trial

Abstract

Background: Growth hormone-deficient adults have increased cardiovascular mortality. Growth hormone replacement may affect cardiovascular risk. Inflammation plays an important role in atherosclerosis, and inflammatory markers are predictive of cardiovascular events.

Objective: To investigate the effect of growth hormone replacement on inflammatory and other cardiovascular risk factors.

Design: Randomized, single-blind, placebo-controlled trial.

Patients: 40 men with adult-onset growth hormone deficiency.

Intervention: Growth hormone or placebo given for 18 months at a dose adjusted for normal serum insulin-like growth factor I level.

Measurements: Anthropometric, hemoglobin A1c, and central fat values were assessed every 6 months. Levels of glucose, insulin, insulin-like growth factor I, and lipids were measured at 1, 3, 6, 12, and 18 months. C-reactive protein, serum amyloid polypeptide A, inteleukin-6, and lipoprotein(a) levels were determined at baseline and 6 and 18 months.

Results: C-reactive protein and inteleukin-6 levels decreased in growth hormone recipients compared with placebo recipients (differences between groups, -1.9 +/- 0.6 mg/L [P = 0.0027] and -1.3 +/- 0.5 ng/L [P = 0.013], respectively). Changes in serum amyloid polypeptide A levels between groups did not reach statistical significance (difference between groups, -2.4 +/- 1.2 mg/L; P = 0.056). Serum cholesterol levels, low-density lipoprotein cholesterol levels, and ratios of total cholesterol to high-density lipoprotein cholesterol decreased in growth hormone recipients in the first 3 months compared with placebo recipients (differences between groups, -0.86 +/- 0.17 mmol/L [-33.2 +/- 6.6 mg/dL] [P < 0.001], -0.63 +/- 0.20 mmol/L [-24.5 +/- 5.9 mg/dL] [P < 0.001], and -0.56 +/- 0.26 [P = 0.040], respectively), but the decrease was not maintained from month 6 to month 18. Lipoprotein(a) levels increased (difference between groups, 22.0 +/- 8.0 mg/L; P = 0.0096). Short-term increases occurred in glucose levels, insulin levels, and insulin-to-glucose ratios (differences between groups, 0.54 +/- 0.16 mmol/L [9.6 +/- 2.8 mg/dL] [P = 0.0018], 37.9 +/- 9.6 pmol/L [P < 0.001], and 6.0 +/- 1.8 [P = 0.0025], respectively), but only the increase in glucose level was maintained over the long term (difference between groups, 0.56 +/- 0.17 mmol/L [10.0 +/- 3.1 mg/dL]; P = 0.0026). Hemoglobin A1c values did not change. Truncal fat-to-total fat ratios decreased (difference between groups, -0.018 +/- 0.007; P = 0.0087).

Conclusions: Long-term growth hormone replacement in men reduces levels of inflammatory cardiovascular risk markers, decreases central fat, and increases lipoprotein(a) and glucose levels without affecting lipid levels.