Calcium requirements after parathyroidectomy in patients with refractory secondary hyperparathyroidism

Calcium supplements are often required following successful parathyroidectomy (PTX) in order to prevent overt hypocalcemia. The current study aims to quantify these calcium needs and to identify predictors of a high calcium need present at the time of surgery.

Charts of 42 patients with chronic kidney disease stage 5D, who underwent a successful subtotal PTX, were reviewed in detail. Biochemical indices of mineral metabolism available within a time frame of 4 weeks before and 6 weeks after the surgery were registered. Details concerning active vitamin D (1-alpha-calcidiol and calcitriol) and calcium supplementation were recorded as well.

Serum calcium, phosphorus and PTH levels declined whereas total alkaline phosphatase levels increased significantly in the early post-PTX period. Transient hypocalcemia was observed in 83% of the patients. The median daily postoperative elemental calcium requirements amounted to 3.2 g during week 1, and declined to 2.4 g during week 6. A high preoperative PTH level and a low serum calcium level were identified as independent predictors of a high postoperative calcium need.

Substantial amounts of elemental calcium are required following successful subtotal PTX in order to avoid frank hypocalcemia, especially in patients with a high PTH level and a low calcium level before surgery.