BODY-COMPOSITION AND FUEL METABOLISM AFTER KIDNEY GRAFTING

Kidney transplant patients display decreased muscle mass and increased fat mass. Whether this altered body composition is due to glucocortic oid induced altered fuel metabolism is unclear. To answer this questio n, 16 kidney transplant patients were examined immediately after kidne y transplantation (12 +/- 4 days, mean +/- SEM) and then during months 2, 5, 11 and 16, respectively, by whole body dual energy X-ray absorp tiometry (Hologic QDR 1000W) and indirect calorimetry. Results mere co mpared with those of 16 age, sex and body mass index matched healthy v olunteers examined only once. All patients received dietary counsellin g with a step 1 diet of the American Heart Association and were advise d to restrict their caloric intake to the resting energy expenditure p lus 30%. Immediately after transplantation, lean mass of the trunk was higher by 7 +/- 1% (P < 0.05) and that of the limbs was lower by more than 10% (P < 0.01) in patients than in controls. In contrast, no dif ference in fat mass and resting energy expenditure could be detected b etween patients and controls. During the 16 months of observation, tot al fat mass increased in male (+ 4.9 +/- 1.5 kg), but not in female pa tients (0.1 +/- 0.8 kg). The change in fat mass observed in men was du e to an increase in all subregions of the body analysed (trunk, arms legs as well as head + neck), whereas in women only an increase in he ad + neck by 9 +/- 2% (P = 0.05) was detected. Body fat distribution r emained unchanged in both sexes over the 16 months of observation. Lea n mass of the trunk mainly decreased between days 11 and 42 (P < 0.01) and remained stable thereafter. After day 42, lean mass of arms and l egs (mostly striated muscle) and head + neck progressively increased o ver the 14 months of observation by 1.6 +/- 0.6 kg (P < 0.05) and 0.4 +/- 0.1 kg (P < 0.01), respectively. Resting energy expenditure was si milar in controls and patients at 42 days (30.0 +/- 0.7 vs. 31.0 +/- 0 .9 kcal kg(-1) lean mass) and did not change during the following 15 m onths of observation. However, composition of fuel used to sustain res ting energy expenditure in the fasting state was altered in patients w hen compared with normal subjects, i.e. glucose oxidation was higher b y more than 45% in patients (P < 0.01) during the second month after g rafting, but gradually declined (P < 0.01) over the following 15 month s to values similar to those observed in controls. Protein oxidation w as elevated in renal transplant patients on prednisone at first measur ement, a difference which tended to decline over the study period. In contrast to glucose and protein oxidation, fat oxidation was lower in patients 42 days after grafting (P < 0.01), but increased by more than 100% reaching values similar to those observed in controls after 16 m onths of study. Mean daily dose of prednisone per kg body weight corre lated with the three components of fuel oxidation (r > 0.93, P < 0.01) , i.e. protein, glucose and fat oxidation. These results indicate that in prednisone treated renal transplant patients fuel metabolism is re gulated in a dose-dependent manner. Moreover, dietary measures, such a s caloric and fat intake restriction as well as increase of protein in take, can prevent muscle wasting as well as part of the usually observ ed fat accumulation. Furthermore, the concept of preferential upper bo dy fat accumulation as consequence of prednisone therapy in renal tran splant patients haste be revised.