Impaired thermoregulation in adults with growth hormone deficiency during heat exposure and exercise

It has recently been shown that patients with growth hormone deficiency have a reduced sweating capacity. We hypothesize that reduced sweating might affect thermoregulation in growth hormone deficiency patients. In the present study we have examined thermoregulation in growth hormone deficiency patients.

Six adult growth hormone deficiency patients and six matched controls were exposed to a 90-minute heat period (40 degrees C). On a second day the subjects exercised for 30 minutes under standardized conditions.

On both occasions changes in GH secretion, sweating and temperature were registered. Heat storage and evaporation were calculated from these data.

We found that during the moderate heat exposure, evaporation was less (56.7 vs 115.6 W, P = 0.0037) and heat storage greater (60.7 vs 37.0 W, P = 0.025) in growth hormone deficiency patients compared to their matched controls. Two of the six patients reacted with severe clinical symptoms of heat exhaustion, whereas the controls were unaffected. After exercise the patients reached significantly higher core temperatures than their matched controls (38.1 vs 37.8 degrees C, P = 0.0097).

Thus, our findings are indicative of a reduced thermoregulatory function in some patients with GH deficiency.