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This version published online on June 2, 2009 Journal of Clinical Endocrinology & Metabolism , doi:10.1210/jc.2009-0026
Submitted on January 6, 2009 Skeletal Muscle Mass in Acromegaly Assessed by Magnetic Resonance Imaging and Dual Photon X-ray AbsorptiometryPamela U. Freda*,Departments of Medicine and Radiology, Columbia University College of P & S, New York, NY 10032; New York Obesity Research Center, St. Luke's-Roosevelt Hospital, and Institute of Human Nutrition, Columbia University College of P & S., New York, NY 10025; Medicine, Mount Sinai School of Medicine, New York, NY 10029; Merck Research Laboratories, Rahway, NJ * To whom correspondence should be addressed. E-mail: puf1{at}columbia.edu.
Context: GH and IGF-I are nitrogen retaining and anabolic, but the impact of long-term exposure to supra-physiologic GH and IGF-I, either from endogenous overproduction in acromegaly or exogenous sources, on skeletal muscle (SM) mass is not clear. Objectives: To assess SM mass by whole body MRI in acromegaly and to test the hypothesis DXA lean tissue mass derived estimates of SM accurately estimate true SM mass. Design, Setting and Patients: Cross-sectional study in 27 acromegaly patients compared to predicted models developed in 315 non-acromegaly subjects and to matched controls. Outcome Measures: Mass of SM from whole-body MRI and lean tissue from DXA. Results: SM mass did not differ from predicted or control values in active acromegaly; 31.75 ± 8.6 kg (acromegaly) vs. 33.06 ± 8.9 kg (predicted); SM was 95.6 ± 12.8% of predicted (rg. 66.7 - 122%) (p=0.088). Lean tissue mass (DXA) was higher in acromegaly than controls; 65.91 ± 15.2 kg vs. 58.73 ± 13.5 kg (p <.0001). The difference between lean tissue mass (DXA) and SM in acromegaly patients was higher than that in controls (p<.0001) consistent with an enlarged non-SM lean compartment in acromegaly. SM mass predicted by DXA correlated highly with SM mass by MRI (r=0.97, p<0.0001). SM (MRI)/SM (DXA predicted) ratio was 1.018 (rg. 0.896 – 1.159) indicating high agreement of these measures of SM. Conclusions: SM mass in active acromegaly patients did not differ from predicted values. SM mass estimated from DXA agreed highly with SM by MRI, supporting the validity of the DXA model in assessing SM in acromegaly and other disorders of GH/IGF-I secretion. Key words: Acromegaly • skeletal muscle mass • growth hormone
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