PARATHYROID FUNCTION IN CARDIAC TRANSPLANT PATIENTS - EVALUATION DURING PHYSICAL EXERCISE

The survival rate of heart transplant patients has increased considera bly since the development of new immunosuppressive drugs. In the long term, however, cardiac transplantation results in a high incidence of osteoporosis which represents a major functional handicap. To examine whether patients in the early stages have impaired phosphocalcic metab olism, intact parathyroid hormone (PTH 1-84), native osteocalcin, ioni zed Ca++ and pH were measured at rest and during muscular exercises a dynamic test used to override circadian and ultradian PTH variations. A group of 12 patients receiving the usual immunosuppressive therapy, which is mainly an association of cyclosporin and prednisolone, and 8 sedentary control subjects performed a square-wave endurance test at t he same relative intensity for 30 min. No patient had previous bone di sease and the period since transplantation was 12.2 +/- 2.7 months. Fo r the transplant patients, initial PTH concentrations and responses to exercise were higher (P < 0.01) compared to the control subjects with a dramatic increase after 10 min of recovery. From higher (P < 0.001) resting concentrations, osteocalcin further increased during exercise (P < 0.01) in the heart transplant group but not in the control subje cts. In both groups pH showed the same time-course with a rapid fall d uring exercise (P < 0.05) and Ca++ concentrations increased during the exercise period. (P < 0.01 for patients; P < 0.05 for controls) with a significant fall in both groups after 10 min of recovery (P < 0.01). Despite a tendency for initial Ca++ concentrations to be lower in the patients (P < 0.07), there were no significant differences between bo th groups either for pH or for Ca++. These results show that in the ea rly stage of transplantation, the patients under immunosuppressive the rapy have moderate hyperparathyroidism which precedes the serious comp lications of bone loss in long-term transplant patients.