Sliding Scale Calcium Dosing After Parathyroidectomy Prevents Hypocalcemia
By Kathleen Louden
Medscape Medical News
October 20, 2009 (Chicago, Illinois) — Patients with primary hyperparathyroidism can go home immediately after successful parathyroidectomy, provided that they receive postoperative supplemental oral calcium, with doses adjusted according to their assessed risk for hypocalcemia, a new study finds.
Symptomatic hypocalcemia, a common problem after this procedure, was prevented in more than 92% of 6000 patients (n = 5540) over the 4 years of the study, said lead author Marie Vasher, MD, a first-year surgical resident at the University of South Florida in Tampa.
The 460 patients (~7.7%) who did experience postoperative hypocalcemia symptoms, such as hand paresthesia, perioral tingling, and mental fog, were able to successfully self-medicate with calcium and vitamin D supplements at home in almost all cases, she said. Only 7 of the 460 patients required a visit to the emergency department for intravenous calcium, according to the abstract.
Dr. Vasher presented the results here at the American College of Surgeons 95th Annual Clinical Congress during the Posters of Exceptional Merit session.
Other Centers Can Use This Protocol
Although her center performs a high volume of parathyroidectomies, Dr. Vasher said that "for centers with a smaller volume of [primary hyperthyroidism-related] surgery, I think this calcium protocol would be applicable. They can institute a similar protocol before the patient leaves the hospital."
All patients in the study were discharged within 2.5 hours and were instructed to take oral calcium citrate–vitamin D tablets (Citracal Regular 250 mg + D [Bayer HealthCare LLC], with each tablet containing 250 mg of calcium and 200 IU of vitamin D) beginning 3 hours postoperatively, Dr. Vasher said in an interview with Medscape General Surgery. Patients reported their hypocalcemia symptoms for 2 weeks.
The calcium dosing protocol is a "sliding scale," with the physicians initially prescribing the highest doses during the first 2 postoperative weeks and decreasing these baseline doses to maintenance levels by the third week, Dr. Vasher said.
The baseline dose depends on whether the patient has an adenoma or hyperplasia. Higher calcium–vitamin D doses are prescribed after parathyroidectomy to patients who have a greater number of risk factors for symptomatic postoperative hypocalcemia, she said.
These risk factors include degree of preoperative serum calcium elevation (levels greater than 12, 13, or 14 mg/dL) in patients with adenomas, severe osteoporosis (bone density T-score less than ?3), morbid obesity (body mass index greater than or equal to 40 kg/m2), the removal of more than 1 parathyroid gland, and the manipulation or biopsy of the remaining glands. For instance, the higher the calcium level preoperatively in a patient with a parathyroid adenoma, the greater the risk for symptomatic hypocalcemia after surgery and, thus, the more calcium that is prescribed postoperatively, Dr. Vasher explained.
Each independent risk factor increases the patient's daily baseline calcium requirement by 315 mg, she said.
"Our protocol represents a baseline for the amount of calcium that a given patient will require following successful parathyroidectomy for the treatment of primary hyperparathyroidism," she told Medscape General Surgery. "Each patient . . . will ultimately require an individualized number of calcium tablets per day based upon his or her response to the baseline dosage."
The new data confirm results of a study of a smaller number of patients that Dr. Vasher's coauthors reported 2 years ago (Endocr Pract. 2007;13:105-113). That earlier study includes specific details about the calcium protocol used in this study.
Proactive Approach Justified
Clinical Congress Program Committee Chair Barbara Bass, MD, who led a discussion of the poster session, told Medscape General Surgery that this study justifies a proactive approach of prescribing calcium–vitamin D supplements after parathyroid gland removal to prevent the development of hypocalcemia symptoms.
Dr. Bass, chair of the Department of Surgery at Methodist Hospital in Houston, Texas, who was not affiliated with the study, called calcium supplementation appropriate treatment to prevent hypocalcemia. The results, she said, might help surgeons who are unsure whether to supplement with calcium their patients undergoing parathyroidectomy.
However, she added, "I would say that most surgeons around the country give every patient a calcium–vitamin D supplement after parathyroidectomy. It's easy to prevent hypocalcemia in these patients. Calcium is such an inexpensive, safe supplement."
Dr. Vasher and Dr. Bass have disclosed no relevant financial relationships.
American College of Surgeons 95th Annual Clinical Congress: Surgical Exhibit SE109. Presented October 14, 2009.
