Low IGF-I levels are often uncoupled with elevated GH levels in catabolic conditions

Increased GH together with decreased IGF-I levels pointing to peripheral GH insensitivity in critically ill patients have been reported by some but not by other authors. To clarify whether elevated GH levels are coupled with low IGF-I levels in all catabolic conditions, basal GH and IGF-I levels were evaluated in patients with sepsis (SEP, no. = 13; age [mean ± SE] = 59.2 ± 1.2 yr), trauma (TRA, no. = 16; age = 42.3 ± 3.4 yr), major burn (BUR, no. = 26; age = 52.8 ± 4.2 yr) and postsurgical patients (SUR, no. = 11; age = 55.0 ± 4.7 yr) 72 hours after ICU admission or after cardiac surgery. GH and IGF-I levels were also evaluated in normal subjects (NS, no. = 75; age = 44.0 ± 1.5 yr), in adult hypopituitaric patients with severe GH deficiency (GHD, no. = 54; age = 44.8 ± 2.3 yr), in patients with liver cirrhosis (LC, no. = 12; age = 50.4 ± 2.8 yr) and in patients with anorexia nervosa (AN, no.= 19; age = 18.7 ± 0.8 yr). Basal IGF-I and GH levels in GHD were lower than in NS (68.6 ± 6.4 vs 200.9 ± 8.7 μg/l and 0.3 ± 0.1 vs 1.4 ± 0.2 μg/l; p < 0.01). On the other hand, AN and LC showed IGF-I levels (70.4 ± 9.1 and 52.4 ± 10.5 μg/l) similar to those in GHD while GH levels (10.0 ± 2.8 and 7.9 ± 2.1 μg/l) were higher than those in NS (p < 0.01). IGF-I levels in SEP (84.5 ± 8.8 μg/l) were similar to those in GHD, AN and LC and lower than those in NS (p < 0.01). IGF-I levels in BUR (105.2 ± 10.9 μg/l were lower than in NS (p < 0.01) but higher than those in GHD, AN, LC and SEP (p < 0.01). On the other hand, in TRA (162.8 ± 17.4 μg/l) and SUR (135.0 ± 20.7 μg/l) IGF-I levels were lower but not significantly different from those in NS and clearly higher than those in GHD, AN, LC, SEP and BUR, Basal GH levels in SEP (0.6 ± 0.2 μg/l), TRA (1.8 ± 0.5 μg/l), SUR (2.2 ± 0.5 μg/l) and BUR (2.2 ± 0.5 μg/l) were similar to those in NS, higher (p < 0.05) than those in GHD and lower (p < 0.01) than those in AN and LC. In conclusion, our data demonstrate that low IGF-I levels are not always coupled with elevated GH levels in all catabolic conditions. Differently from cirrhotic and anorectic patients, in burned and septic patients GH levels are not elevated in spite of very low IGF-I levels similar to those in panhypopituitaric GHD patients. These findings suggest that in some catabolic conditions peripheral GH insensitivity and somatotrope insufficiency could be concomitantly present.