Human growth hormone effect on serum IGF-I and muscle function in poliomyelitis survivors

Previous work showed low insulin-like growth factor I (IGF-I) in polio survivors compared with age-matched controls and it was hypothesized that the low IGF-I was caused by the lack of growth hormone (GH) secretion. The present study asked: Is the nocturnal release of GH subnormal in polio survivors? Can the low IGF-I level be raised to the range of healthy young men (240 to 460ng/mL) by human growth hormone (hGH) treatment? If so, what dose of hGH is required? Does the hormone treatment affect muscle function? Eleven polio survivors with evidence of postpoliomyelitis syndrome, aged 50 to 65 years, and low IGF-I levels (average IGF-I value of 170ng/mL) were studied. The serum level of GH was measured in the first 4 hours of sleep. The serum IGF-I level was determined before and during hGH treatment at 0.0075, 0.015 or 0.03mg/kg of ideal body weight (IBW), three times a week for successive periods of 1 month. Before and after hGH treatment, strength was determined in knee extensor and flexor muscles and the elbow flexor and elbow extensor muscles. Nocturnal GH was low in the polio survivors compared with healthy young men. Serum IGF-I was raised into the target range by either 0.0075 or 0.015mg hGH/kg three times a week. After 3 months of hGH treatment, no consistent changes in muscle strength were observed in the study group. The study provides new data that the tendency for low serum IGF-I level in polio survivors is caused at least in part by low endogenous GH secretion, and can be corrected by relatively low doses of hGH. Three months of hormone treatment does not regularly improve muscle strength in polio survivors.