General weakness as an indication for parathyroid surgery in patients with secondary hyperparathyroidism

Hypotheses: There are factors that affect patients with general weakness owing to secondary hyperparathyroidism and as reported by results noted after parathyroidectomy and autotransplantation. Design: Case series and consecutive samples. Setting: Tertiary care center. Patients: From July 1996 to June 1998, 56 patients with secondary hyperparathyroidism underwent total parathyroidectomy and autotransplantation. Their ages were 45 +/- 13 years (mean +/- SD) and preoperative duration of dialysis was 75 +/- 37 months. Prior to surgery the patients were divided into 2 groups: group A comprised 2 men and 19 women who had some general weakness; and group B, 15 men and 20 women who reported no general weakness. The etiologies of renal failure, such as diabetic nephropathy (n= 3) or hypertensive nephropathy (n=3), were found only in group A patients. Interventions: Serum levels of calcium, phosphorus, alkaline phosphatase, and parathyroid hormone (intact) were checked preoperatively and 1 day, 1 week, and 3 months after surgery. Extension force of the quadriceps femoris muscle was measured at 60 degrees of right knee flexion preoperatively and 3 months after surgery. The extension force was expressed as newtons (N) in 2 different quantities: peak force and average force. The degree of general weakness was classified into 4 groups: 0, no weakness; 1, some subjective weakness and/or walking with assistance; 2, the patient was wheelchair bound; and 3, the patient was bedridden. Main Outcome Measures: The t test was used for paired and unpaired data; Wilcoxon signed rank and Fisher exact tests were incorporated for nonparametric data. Any values of P<.05 were considered significant. Results: Prior to surgery, 2 patients in group A reported degree 3 weakness; 5, degree 2 weakness, and 14, degree 1 weakness. Three months after surgery, the peak force was noticed to have increased from 185 +/- 56 N to 249 +/- 82 N (mean +/- SD) (n=11, P =.003), and the average force showed an increase from 136 45 N to 202 +/- 69 N (n = 11,P =.003). Postoperatively, only 5 patients had degree 1 weakness, 1 had degree 2 weakness, and none had degree 3 weakness. The patient with degree 2 weakness after surgery had diabetes mellitus and a femoral neck fracture prior to parathyroidectomy. Improvement in condition of general weakness was found (P<.001) between preoperative and postoperative periods. Serum levels of calcium were higher in group A (2.82 +/- 0.23 mmol/L [11.3 +/- 0.9 mg/dL]) than in group B (2.64 +/- 0.27 mmol/L [10.6 +/- 1.1 mg/dL]) (P =.013), and serum levels of parathyroid hormone (intact) were lower in group A (108.9 +/- 39.2 pmol/L) than in group B (139.8 +/- 39.6 pmol/L) (P=.006). Except for sex, other data such as phosphorus and alkaline phosphatase levels, age, and duration of dialysis were not significantly different between the 2 groups. Conclusions: General weakness that is commonly observed in patients with secondary hyperparathyroidism is found more frequently in women and only in patients with diabetic nephropathy or hypertensive nephropathy. Patients with general weakness had relatively higher levels of calcium and lower levels of parathyroid hormone (intact). We found that improvement of muscle power and general weakness can be achieved by parathyroidectomy and autotransplantation. In addition to itchy skin, bone pain, and soft tissue calcification, general weakness that may cause disability is also an indication for surgery in secondary hyperparathyrodism.