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WASHINGTON — A serum 25-hydroxyvitamin D level below 30 ng/mL appears to define vitamin D deficiency, Paraskevi Sapountzi, M.D., reported at the annual meeting of the American Association of Clinical Endocrinologists.
Vitamin D deficiency can lead to secondary hyperparathyroidism, decreased calcium absorption, and poor response to therapy. But recent reports of assay variability have led to confusion about interpretation of the metabolite 25(OH)D levels, and not enough data are available to guide clinicians regarding when to initiate vitamin D therapy, said Dr. Sapountzi, of Loyola University, Chicago.
In a retrospective analysis of 143 female and 20 male patients who had been evaluated for low bone mass at the university's Osteoporosis and Metabolic Bone Disease Center, the patients had a mean age of 62.5 years, a mean 25(OH)D level of 29.8 ng/mL, a mean parathyroid hormone (PTH) level of 61.7 pg/mL, a mean urine calcium level of 215.7 mg/24 hours, and a mean spine T score of −1.9. None of the patients were on vitamin D therapy or had primary hyperparathyroidism, Dr. Sapountzi said.
Initially, vitamin D insufficiency was defined as a 25(OH)D level of less than 20 ng/mL, based on the laboratory's reference range and data from one study suggesting that 20 ng/mL represents the cutoff below which the risk for secondary hyperparathyroidism increases. Using that definition, 26.4% of the 163 patients had vitamin D insufficiency.
The 25(OH)D level was significantly correlated with PTH and with urinary calcium, with the difference between the means of PTH above and below a 25(OH)D level of 30 ng/mL being significant. At 35 ng/mL, the significance was lost. Using the new cutoff of 30 ng/mL for vitamin D deficiency raised the prevalence among the patients to 48%, she said.
A 25(OH)D level of 30 ng/mL also showed significant differences in the urinary calcium levels of patients with 25(OH)D above and below that threshold. This relationship also was significant at 35 ng/mL and was lost at 40 ng/mL.
The strong correlation between urinary calcium, PTH, and 25(OH)D emphasizes the importance of this test in the work-up of osteoporosis, she remarked.
WASHINGTON — A serum 25-hydroxyvitamin D level below 30 ng/mL appears to define vitamin D deficiency, Paraskevi Sapountzi, M.D., reported at the annual meeting of the American Association of Clinical Endocrinologists.
Vitamin D deficiency can lead to secondary hyperparathyroidism, decreased calcium absorption, and poor response to therapy. But recent reports of assay variability have led to confusion about interpretation of the metabolite 25(OH)D levels, and not enough data are available to guide clinicians regarding when to initiate vitamin D therapy, said Dr. Sapountzi, of Loyola University, Chicago.
In a retrospective analysis of 143 female and 20 male patients who had been evaluated for low bone mass at the university's Osteoporosis and Metabolic Bone Disease Center, the patients had a mean age of 62.5 years, a mean 25(OH)D level of 29.8 ng/mL, a mean parathyroid hormone (PTH) level of 61.7 pg/mL, a mean urine calcium level of 215.7 mg/24 hours, and a mean spine T score of −1.9. None of the patients were on vitamin D therapy or had primary hyperparathyroidism, Dr. Sapountzi said.
Initially, vitamin D insufficiency was defined as a 25(OH)D level of less than 20 ng/mL, based on the laboratory's reference range and data from one study suggesting that 20 ng/mL represents the cutoff below which the risk for secondary hyperparathyroidism increases. Using that definition, 26.4% of the 163 patients had vitamin D insufficiency.
The 25(OH)D level was significantly correlated with PTH and with urinary calcium, with the difference between the means of PTH above and below a 25(OH)D level of 30 ng/mL being significant. At 35 ng/mL, the significance was lost. Using the new cutoff of 30 ng/mL for vitamin D deficiency raised the prevalence among the patients to 48%, she said.
A 25(OH)D level of 30 ng/mL also showed significant differences in the urinary calcium levels of patients with 25(OH)D above and below that threshold. This relationship also was significant at 35 ng/mL and was lost at 40 ng/mL.
The strong correlation between urinary calcium, PTH, and 25(OH)D emphasizes the importance of this test in the work-up of osteoporosis, she remarked.
WASHINGTON — A serum 25-hydroxyvitamin D level below 30 ng/mL appears to define vitamin D deficiency, Paraskevi Sapountzi, M.D., reported at the annual meeting of the American Association of Clinical Endocrinologists.
Vitamin D deficiency can lead to secondary hyperparathyroidism, decreased calcium absorption, and poor response to therapy. But recent reports of assay variability have led to confusion about interpretation of the metabolite 25(OH)D levels, and not enough data are available to guide clinicians regarding when to initiate vitamin D therapy, said Dr. Sapountzi, of Loyola University, Chicago.
In a retrospective analysis of 143 female and 20 male patients who had been evaluated for low bone mass at the university's Osteoporosis and Metabolic Bone Disease Center, the patients had a mean age of 62.5 years, a mean 25(OH)D level of 29.8 ng/mL, a mean parathyroid hormone (PTH) level of 61.7 pg/mL, a mean urine calcium level of 215.7 mg/24 hours, and a mean spine T score of −1.9. None of the patients were on vitamin D therapy or had primary hyperparathyroidism, Dr. Sapountzi said.
Initially, vitamin D insufficiency was defined as a 25(OH)D level of less than 20 ng/mL, based on the laboratory's reference range and data from one study suggesting that 20 ng/mL represents the cutoff below which the risk for secondary hyperparathyroidism increases. Using that definition, 26.4% of the 163 patients had vitamin D insufficiency.
The 25(OH)D level was significantly correlated with PTH and with urinary calcium, with the difference between the means of PTH above and below a 25(OH)D level of 30 ng/mL being significant. At 35 ng/mL, the significance was lost. Using the new cutoff of 30 ng/mL for vitamin D deficiency raised the prevalence among the patients to 48%, she said.
A 25(OH)D level of 30 ng/mL also showed significant differences in the urinary calcium levels of patients with 25(OH)D above and below that threshold. This relationship also was significant at 35 ng/mL and was lost at 40 ng/mL.
The strong correlation between urinary calcium, PTH, and 25(OH)D emphasizes the importance of this test in the work-up of osteoporosis, she remarked.