Which adults develop side-effects of growth hormone replacement?

OBJECTIVE: Although the nature of the side-effects of GH replacement in adults are well described, the factors influencing their development are ill understood. The aim of this study was to determine whether there were any characteristics of adults with GH deficiency that predicted whether or not they developed side-effects of GH replacement.

DESIGN: A 12-month study (double blind placebo controlled for the first 6 months and open for the second 6 months) of GH replacement (0.125 IU/kg/week for the first month and 0.25 IU/kg/week thereafter) in adults.

PATIENTS: Sixty-three adults (27 men, 36 women, aged 34.9 +/- 1.4 (mean +/- SE, range 20.1-59.5 years)) with GH deficiency (peak serum GH response to provocative testing of less than 10 mU/l) who took part in a 12-month study of GH replacement. Twenty-five patients (40%) did not develop side-effects, 19 patients (30%) developed side-effects which did not necessitate a reduction in dose of GH, and 19 patients (30%) required a reduction in dose of GH because of side-effects.

MEASUREMENTS: The three groups of patients were compared according to age, height, weight and body mass index (BMI) at entry into the study and to pretreatment peak serum GH response to provocative testing. They were also compared according to serum concentration of insulin-like growth factor (IGF)-I and IGF binding protein-3, and age-adjusted serum IGF-I standard deviation score (SDS), at entry into the study and by change in these measurements after 6 months of GH replacement. The patient's sex, whether GH deficiency was of childhood or adult onset, estimated duration of GH deficiency, presence or absence of additional pituitary hormone deficiencies, underlying pathological disorder and previous therapeutic interventions were also compared in the three groups of patients.

RESULTS: Those patients who required a reduction in dose of GH because of side-effects were more likely to have a peak serum GH response of greater than 1 mU/l (P = 0.005) and to have adult onset GH deficiency (P = 0.04) than those who did not develop side-effects or who did not require a reduction in dose of GH because of side-effects. In addition, those who needed a reduction in GH dose were older (P = 0.002), heavier (P = 0.04) and had a greater BMI (P = 0.003) than those who did not develop side-effects. Those who developed side-effects but did not require a reduction in dose of GH had a greater increment in IGF-I SDS after 6 months of GH replacement than those who did not develop side-effects (P = 0.03).

CONCLUSION: Side-effects of GH replacement are more likely to occur in older patients, in those with a peak serum GH response to provocative testing of greater then 1 mU/l, in those with a greater increment in serum IGF-I SDS whilst receiving GH replacement, in those with greater weight and BMI, and those with adult onset GH deficiency.