DHEA-S levels in hypopituitaric patients with severe GH deficiency are strongly reduced across lifespan. Comparison with IGF-I levels before and during rhGH replacement

Abstract

Both IGF-I and DHEA-S undergo an age-related decrease and their decrease could be involved in age-related changes in body composition, structure functions and metabolism. On the other hand, it is well known that mean IGF-I levels are clearly reduced in hypopituitaric patients with GH deficiency (GHD) while data about dehydroepiandrosterone sulfate (DHEA-S) levels in hypopituitarism are scanty. We evaluated DHEA-S and IGF-I levels and their relationship in 90 patients with panhypopituitarism (HYPOPIT) with severe GHD [49 women and 41 men; age, mean+/-SE: 47.9+/-1.49 yr, range: 20-80 yr, BMI: 26.4+/-0.6 kg/m2; 21 with childhood-onset (CO) and 69 with adult-onset (AO) HYPOPIT]. DHEA-S and IGF-I levels were also evaluated in 24 HYPOPIT with GHD after 3-month recombinant human GH (rhGH) replacement. Data in HYPOPIT were compared with those in a large group of healthy controls (NS, 233 women and 103 men, aged 20-80 yr; all subjects were within +/-15% of their ideal body weight). In NS both DHEA-S levels and IGF-I were gender-independent while showed a strong, inverse correlation with age (r=-0.6; p<0.001 and r=-0.56; p<0.0001, respectively). Nevertheless, no relationship was found between DHEA-S and IGF-I levels in NS. In HYPOPIT, age-adjusted mean DHEA-S and IGF-I levels were clearly lower than those in NS (2.3+/-0.4 vs 16.0+/-0.7 microg/l, p<0.005; 71.1 +/- 4.5 vs 170+/-4.7 microg/l, p<0.005). IGF-I levels in CO-HYPOPIT were lower (p<0.01) than those in AO-HYPOPIT (49.6+/-4.8 vs 77.0+/-5.4 microg/l), while DHEA-S levels were similar in both subgroups (2.6+/-0.7 vs 2.3+/-0.4 microg/l). In HYPOPIT both DHEA-S and IGF-I were independent of age and gender while there was a trend toward a positive association between each other (r=0.45; p<0.003). Analyzing individual levels in HYPOPIT with respect to age-adjusted normal ranges, IGF-I levels were below normal in 84, 62 and 0% between 20-40, 40-60 and 60-80 yr, respectively. On the other hand, DHEA-S levels were below normal in 84, 86 and 67% between 20-40, 40-60 and 60-80, respectively. In HYPOPIT rhGH treatment strikingly increased IGF-I levels (150+/-3.2 vs 85.3+/-4.1 microg/l, p<0.005) while did not modify DHEA-S levels (1.7+/-0.2 vs 1.6+/-0.2 microg/l). In conclusion, our results demonstrate that DHEA-S and IGF-I are negatively and independently associated to age in physiological conditions but not in hypopituitaric patients in whom both are strikingly reduced. Both DHEA-S and IGF-I levels in HYPOPIT show some overlap with those in normal subjects; thus the assay of these parameters is not diagnostic for hypopituitarism. DHEA-S reduction in HYPOPIT does not depend on IGF-I as indicated also by evidence that GH replacement restores IGF-I but does not modify DHEA-S levels.