Endocrine Abstracts

Introduction: It is known that growth hormone secretion is affected by age and patient’s sex. We have assessed pre-treatment IGF-1 levels and responses to a standard dose of exogenous growth hormone (0.4 mg daily) in males and females arbitrarily categorised into young (20–40 yrs), middle-aged (40–60 yrs) and elderly (over 60 yrs). All patients were growth hormone deficient on either an insulin tolerance test or a glucagon test, peak growth hormone did not rise above 2.0 mU/L in any patient. We studied 156 male/female patients aged 20–60+. Mean age (20–40 yrs) female 32 yrs, male 27 yrs(49pts) Mean age (40–60 yrs) female 51 yrs, male 49 yrs(79pts) Mean age (60+) female 69 yrs, male 68 yrs(28pts).

Results: Pre-treatment in the young group showed 20% with subnormal IGF-1. The time to achieve a normal IGF-1 was 16–24weeks and IGF-1 values on treatment were all below the mean. In the middle-aged group, 40% had an IGF-1 pre-treatment that was normal. The attainment of a normal IGF-1 was quicker than the younger group 8 weeks in men, 12–16weeks in women No patient showed values above the normal range. In the 60+ group, 75% had a normal pre-treatment IGF-1. Responses were rapid, IGF-1 above mid range after 4–8 weeks in men, 8–12 weeks in women. More than 50% of men showed IGF-1 values that were above normal and had to have their dose reduced.

Conclusions: 1.Young patients are less sensitive to growth hormone and should commence treatment 0.4 mg daily then titrate using IGF-1 as an indicator, average dose 0.8 mg daily.

2.Men are more sensitive to the affects of growth hormone than women and, in middle-aged women, the dose should usually be 0.3 mg per day.

3. In the 60+ group, patients require less replacement, treatment should commence with does of 0.1 mg per day. This group respond quickly to treatment and require careful monitoring for optimum results.