The serum growth hormone to somatostatin ratio is skewed upward in rheumatoid arthritis patients

Basal serum growth hormone, insulin-like growth factor-1 (IGF-1) and somatostatin concentration were measured by standard radioimmunoassay in patients with a diagnosis of rheumatoid arthritis (RA) according to the criteria of the American College of Rheumatology as well as in a group of age-matched normal subjects. RA patients exhibited significantly elevated (age, 45-55 yrs, p less than 0.05; 55 yrs and older, p less than 0.01) serum growth hormone levels compared to age-matched individuals from the control group. IGF-1 was unchanged. Serum somatostatin levels were reduced in RA patients between 45 and 55 yrs but reached a significant reduction (p less than 0.0001) in RA patients, 55 years and older compared to age-matched individuals from the control group. RA patients treated with prednisone did not exhibit changes in either growth hormone or IGF-1 levels compared to RA patients treated principally with non-steroidal anti-inflammatory drugs and methotrexate. These results indicated that symptomatic RA is associated with elevated serum growth hormone without concomitant changes in IGF-1 compared to individuals from the control group. Reduced somatostatin levels in older RA patients resulted in a skewed upward growth hormone to somatostatin ratio. We conclude that the serum growth hormone to somatostatin ratio may be a useful surrogate marker of disease activity in symptomatic RA.