Altered growth hormone (GH) kinetics in rheumatoid arthritis (RA)

We have previously demonstrated alterations in GH kinetics and a reduction in body cell mass (BCM) among patients with RA compared to healthy young and elderly individuals. However, because GH production declines with age, it remains unclear whether the alteration in GH is primarily an age- or disease-related phenomenon. Therefore, we examined 24-hr GH kinetics among 12 patients with RA and 25 healthy individuals of the same age range (22-65 yr). 24-hr GH kinetics were determined by deconvolution analysis. After controlling for age and BCM, 24-hr mean and integrated GH levels were lower among RA compared to healthy subjects (0.86 ± 0.45 vs. 1.19 ± 0.96 ng/ml, and 1228.2 ± 638.2 vs. 1685.7 ± 1423.5 ng, respectively, p < 0.05). There was a trend toward lower GH production rates in the RA vs. healthy subjects (44.6 ± 25.5 vs. 51.3 ± 41.3 ng/ml/d, respectively, p = 0.08). These findings suggest that: 1) reduced circulating GH occurs in RA compared to nealthy individuals of similar age and body composition, and 2) decreased GH production rates may contribute to reduced circulating GH levels in RA.