Paricalcitol Doesn't Up Calcium Level In Renal Failure.
ORLANDO, FLA. -- The vitamin D analog paricalcitol is unlikely to raise serum levels of calcium and phosphorus when treating secondary hypoparathyroidism Hypoparathyroidism Definition
Hypoparathyroidism is the result of a decrease in production of parathyroid hormones by the parathyroid glands located behind the thyroid glands in the neck. The result is a low level of calcium in the blood. among patients with chronic renal failure chronic renal failure Chronic kidney failure Nephrology A slow decline in renal function, which may be 2º to chronic HTN, DM, CHF, SLE, or sickle cell anemia and, if extreme, leads to ESRD, mandating kidney dialysis; an abrupt decline in renal function may be .
Paricalcitol (Zemplar), which has been on the U.S. market since 1998, "suppresses parathyroid hormone [PTH PTH
Parathyroid hormone (PTH)
A chemical substance produced by the parathyroid glands. This hormone is a major element in regulating calcium in the body. ] at doses that do not raise serum levels of calcium and phosphorus," Dr. Kevin J. Martin said at a meeting on clinical nephrology sponsored by the National Kidney Foundation. In several placebo-controlled trials, treatment with paricalcitol cut PTH levels by about 60% and left serum calcium and phosphorus levels virtually unchanged.
Paricalcitol has about one-fourth to one-third the potency of calcitriol for reducing PTH levels, but with one-eighth the potency of calcitriol for increasing serum calcium and phosphorus, said Dr. Martin, a professor of internal medicine at St. Louis University.
Another calcitriol analog, doxercalciferol (Hectorol), also controls PTH while modestly increasing serum calcium and phosphorus. Direct clinical comparisons of doxercalciferol and paricalcitol have not yet been reported, but comparison-studies in animals showed that paricalcitol caused less of an increase in serum calcium than did doxercalciferol, according to Dr. Martin. A head-to-head clinical study of the two analogs is needed to resolve this issue.
About 60%-70% of dialysis patients have a PTH level higher than 400 pg/mL and need some form of treatment to control their secondary hyperparathyroidism Hyperparathyroidism Definition
Parathyroid glands are four pea-sized glands located just behind the thyroid gland in the front of the neck. The function of parathyroid glands is to produce a hormone called parathyroid hormone (parathormone), which helps , Dr. Martin said.