Muscle strength and endurance after surgery for primary hyperparathyroidism.

OBJECTIVE

To evaluate the effect of surgery on muscular strength and endurance in patients with primary hyperparathyroidism (HPT).

DESIGN

Prospective open study.

SETTING

University hospital, Sweden.

SUBJECTS: Nine patients undergoing HPT surgery and nine matched patients undergoing thyroid resection who acted as controls.

INTERVENTIONS: Concentric and eccentric endurance was evaluated with a test comprising 100 repeatedly executed muscle action at 90 degrees.s-1. Blood samples obtained before and after operation were analysed for calcium, phosphate, thyroid stimulating hormone (TSH), and parathyroid hormone (PTH) concentrations.

MAIN OUTCOME MEASURES: Peak torque during maximum voluntary concentric and eccentric muscle actions at 90 degrees.s-1 before, three months and one year after operation.

RESULTS

There were no differences in concentric and eccentric peak torque before and after operation either within or between groups. Concentric and eccentric endurance were similar in the HPT group and controls before as well as after operation. The return of calcium and PTH concentrations to their reference ranges after parathyroidectomy did not correlate with changes in concentric and eccentric peak torque.

CONCLUSIONS

The subjective improvement in muscle endurance which is often encountered in patients with HPT after operation is not associated with an objective increase in muscle strength or endurance as measured by isokinetic muscle performance.