Lower ability to oxidize lipids in adult patients with growth hormone (GH) deficiency: reversal under GH treatment.
BACKGROUND
The aim of the study was to characterize lipid oxidation at exercise in adults with growth hormone deficiency (GHD) and to evaluate the effect of 6 and 12 months of GH replacement therapy on substrate carbohydrate (CHO) and lipid utilization at exercise.


METHODS
Twenty-five patients with GHD and 40 matched controls participated in the study. Ten of the 25 GH-deficient patients were treated with recombinant GH for 12 months. Anthropometric measurements and exercise calorimetry were performed before and after treatment. Maximal fat oxidation and the crossover point [that is the percentage of the theoretical maximal power (Wmax th) where CHO become the predominant fuel used for oxidation] were determined.


CONCLUSIONS
The GH-deficient patients exhibited a highly significant shift in the balance of substrate oxidation during exercise, towards a decrease in fat oxidation, and a shift towards lower intensities of the crossover (52 +/- 5.5%vs. 72.6 +/- 6.6% of Wmax th, P < 0.03) and maximal fat oxidation (131.04 +/- 14 vs. 234.4 +/- 30.1 mg/min, P < 0.03) in the GHD and control groups, respectively. However, GH treatment at 6 and 12 months partially reversed this defect, resulting in an increase (+83%, P < 0.001) in the maximal ability to oxidize fat during exercise. These findings are consistent with the hypothesis that a lack of GH reduces the ability to oxidize lipids during exercise and that GH treatment restores this muscular metabolic property.
Brandou
F
F
Service Central de Physiologie Clinique, Centre d'Exploration et de Réadaptation des Anomalies du Métabolisme Musculaire, CHU Montpellier, France. fredbrandou@yahoo.fr
Aloulou
I
I
Razimbaud
A
A
Fédou
C
C
Mercier
J
J
Brun
J F
JF
D000236:Adenoma / Q000378:metabolism; D000328:Adult; D000704:Analysis of Variance; D001823:Body Composition; D050260:Carbohydrate Metabolism; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D013006:Growth Hormone / Q000172:deficiency* / Q000378:metabolism; D019382:Human Growth Hormone / Q000627:therapeutic use; D006801:Humans; D007018:Hypopituitarism / Q000188:drug therapy / Q000378:metabolism*; D050356:Lipid Metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D010101:Oxygen Consumption; D010911:Pituitary Neoplasms / Q000378:metabolism; D013997:Time Factors
D019382:Human Growth Hormone; D013006:Growth Hormone