BALTIMORE – Patients who have had parathyroidectomy for primary hyperparathyroidism can have disease recurrence 10 years or longer after surgery, raising the possibility that postop follow-up should never end, according to a study presented at the annual meeting of the American Association of Endocrine Surgeons.
Dr. Irene Lou of the University of Wisconsin–Madison reported on results of a retrospective study of 196 patients who had a presumably “curative” parathyroidectomy at the institution between November 2000 and June 2005. The mean age of the study population was 61 years.
Dr. Irene Lou
“The long-term recurrences of primary hyperparathyroidism after curative parathyroidectomy is likely higher than previously reported, with over a third of recurrences occurring 10 years after their operation,” Dr. Lou said.
The study also identified independent predictors of recurrence, among them younger age, a drop in intraoperative parathyroid hormone less than 70%, and double adenoma, Dr. Lou said. All patients after parathyroidectomy should have at minimum an annual serum calcium test, especially younger patients with longer life expectancies, she said. This recommendation, however, may be altered for older patients or those with additional comorbidities.
The study defined recurrence as serum calcium of 10.2 mg/dL or greater 6 months or longer after the initial operation. The overall 10-year recurrence rate was 14.8% and the median time to recurrence was 6.3 years. “We found that 41.4% of patients who recurred did so by 5 years and 65.5% by 10 years,” Dr. Lou said.
The University of Wisconsin and University of Alabama at Birmingham investigators undertook the study because the recent data on recurrence was limited, with the longest study topping out at 7 years, Dr. Lou said. “We previously looked at this problem in other perspectives and we found that a lot of curves separated at around 8 years,” she said.
With regard to the type of operation the patients had, whether unilateral minimally invasive parathyroidectomy or bilateral open surgery, the study found no significant differences in recurrence rates, Dr. Lou said. “This is an excellent study,” Dr. Samuel K. Snyder of Temple, Tex., said during the discussion. “You’re telling us we need to follow patients much longer than perhaps we did previously, but we all see patients who have normal calcium and still have a residual elevated parathyroid hormone level.” He asked if the study considered parathyroid hormone levels at 6 months or more after surgery or vitamin D levels, but Dr. Lou said this information was not available, therefore could not be evaluated.
Dr. Lou and her coauthors had no financial relationships to disclose.