The impact of baseline intact parathyroid hormone levels on severity of primary hyperparathyroidism and outcomes in patients undergoing surgery.

OBJECTIVE

To determine the impact of intact parathyroid hormone (iPTH) baseline levels on severity of primary hyperparathyroidism (PHPT) and outcomes following parathyroidectomy for PHPT.

DESIGN

Single institution retrospective review.

SETTING

Academic tertiary care center.

PATIENTS: A total of 447 consecutive patients undergoing parathyroid surgery for PHPT.

MAIN OUTCOME MEASURES: Comparison of patients with high (> or =150 pg/mL) and low (<150 pg/mL) baseline iPTH values; preoperative serum calcium, alkaline phosphatase, and 25-hydroxyvitamin D levels; and 6-month postoperative serum calcium and iPTH levels.

RESULTS

A total of 304 patients had baseline iPTH values of at least 150 pg/mL (high baseline group), and 143 patients had baseline iPTH values lower than 150 pg/mL (low baseline group). Patients in the high baseline group had significantly higher levels of preoperative serum calcium, serum alkaline phosphatase, and adenoma weights (P < .001 for all comparisons). Serum 25-hydroxyvitamin D levels were significantly lower in patients in the high baseline group (P < .001). Sestamibi scans were more likely to localize an adenoma in the high baseline group (83.7%) than in the low baseline group (68.9%) (P < .01). There were no differences in the serum calcium and iPTH levels between the 2 groups 6 months after surgery.

CONCLUSIONS

Patients in the high baseline group undergoing surgery for PHPT had higher baseline levels of serum calcium, serum alkaline phosphatase, and parathyroid adenoma weights and lower serum 25-hydroxyvitamin D levels compared with the lower baseline group. Sestamibi scans were more likely to localize an adenoma in the high baseline group (83.7%) than in the low baseline group (68.9%) (P < .01). Despite an apparently lower rate of positive preoperative sestamibi scans for the low baseline group, patients were able to achieve a similar rate of disease cure as other patients with higher baseline iPTH levels. It seems that baseline iPTH level should not be used as a criterion to perform surgery or not perform surgery for patients with PHPT.