SAN FRANCISCO — New guidelines for managing patients with asymptomatic primary hyperparathyroidism eliminate urine calcium as an indication for surgery and call for monitoring serum calcium annually instead of every 6 months in patients who do not have surgery.
The guidelines, the product of a 2008 international workshop and consensus panel, recommend parathyroidectomy for patients aged under 50 years with primary hyperparathyroidism and symptoms of hypercalcemia. Surgery also is recommended in asymptomatic patients with serum total calcium 1 mg/dL above the upper limit of normal, or estimated glomerular filtration rate less than 60 mL/min, or bone mineral density T scores of −2.5 or lower at the lumbar spine, hip, or distal third of the radius on dual x-ray absorptiometry (J. Clin. Endocrinol. Metab. 2009;94:335-9).
The guidelines note that medical surveillance of patients who undergo surgery for primary hyperparathyroidism is neither possible nor desirable, Dr. Dolores M. Shoback said at a meeting on diabetes and endocrinology sponsored by the University of California, San Francisco.
For patients who don't go to surgery, the only change in monitoring recommendations compared with the last version of the guidelines in 2002 is the switch from semiannual to annual monitoring of serum calcium levels, said Dr. Shoback, professor of medicine at the university.
Serum creatinine and bone mineral density should be measured at three sites—lumbar spine, hip, and distal third of the radius—yearly. Tests that were included in 1990 guidelines but are no longer recommended include 24-hour urinary calcium, creatinine clearance, and abdominal x-ray.
No medications are approved to treat primary hyperparathyroidism. Studies of alendronate therapy show that it does not reverse or control the biochemical abnormalities of hyperparathyroidism, but it does seem to stabilize or even enhance bone mineral density in these patients, Dr. Shoback said.
The calcium mimetic cinacalcet also has been studied, with some promising results. Physicians might consider using this drug in patients with primary hyperparathyroidism to control hypercalcemia if the patients are too sick for surgery or declined or failed surgery, she said.
Dr. Shoback has been a consultant for Amgen, which markets cinacalcet, and was a researcher on a study examining the use of cinacalcet in parathyroid carcinoma patients.
The natural history of the disease was highlighted in what might be the largest and longest follow-up study that will be seen for a very long time, she said.
Among 116 patients with primary hyperparathyroidism (17 of whom were symptomatic), 51% went straight to surgery, which normalized biochemistries and improved bone mineral density in all patients during 15 years of follow-up (J. Clin. Endocrinol. Metab. 2008;93:3462-70).
The 57 patients who did not have surgery initially for a variety of reasons (although it was recommended to some) tended to remain biochemically stable for the first decade but then developed significant increases in serum calcium levels. Bone density was stable in the lumbar spine but declined significantly after year 9 or 10 in the femoral neck and radius—by 10% and 35%, respectively. In comparison, bone density at these sites increased by 10% or more in patients who initially went to surgery.
Of eight patients who had kidney stones at baseline yet refused recommended surgery, six had recurrent stones during follow-up. Patients with kidney stones who agreed to initial parathyroidectomy had no recurrent stones, Dr. Shoback said.
Medical surveillance of patients who undergo surgery is neither possible nor desirable. DR. SHOBACK