Primary hyperparathyroidism: do perioperative biochemical variables correlate with parathyroid adenoma weight or volume?

OBJECTIVES

To investigate the relationship between clinical variables and biochemical markers of calcium homeostasis and parathyroid adenoma size, in patients undergoing surgery for primary hyperparathyroidism. To determine the potential clinical utility of the findings in preoperative planning and prediction of postoperative hypocalcaemia.

DESIGN

Retrospective data analysis.

PARTICIPANTS

Ninety-two patients treated surgically for primary hyperparathyroidism caused by a solitary parathyroid adenoma between 1996 and 2006.

MAIN OUTCOME MEASURES

Complete data was obtained for 77 participants including patient demographics, perioperative calcium, parathyroid hormone and phosphate levels, adenoma weight and histological dimensions. Multiple and binary logistic regression analyses were used to investigate the relationship between clinical and biochemical variables and adenoma weight and volume. Similar analysis was used to identify predictors of postoperative hypocalcaemia.

SETTING

University Teaching Hospital Otolaryngology Department.

RESULTS

The mean age at presentation was 59 years. The mean preoperative calcium and PTH levels were 2.86 +/- 0.2 mmol/L and 17.2 +/- 12.3 ng/L, respectively, falling to 2.3 +/- 0.01 and 4.1 +/- 2.7 postoperatively. The mean adenoma weight was 1.71 +/- 1.41 g. No correlation existed between clinical variables and preoperative biochemical markers of calcium homeostasis and adenoma weight or volume. There was a weak correlation between the preoperative to postoperative change in calcium and PTH levels {[deltaCa(2)+] vs. [deltaPTH]} (r = 0.24; P < 0.05) but no predictors of postoperative hypocalcaemia could be identified.

CONCLUSIONS

Biochemical parameters will not accurately predict the size of a parathyroid adenoma. The size of a parathyroid adenoma does not correlate with postoperative calcium levels and is therefore not useful as a predictor of postoperative hypocalcaemia.