TY - JOUR
T1 - Role of calcium intake in modulating age-related increases in parathyroid function and bone resorption
AU - Mckane, W. Roland
AU - Khosla, Sundeep
AU - Egan, Kathleen S.
AU - Robins, Simon P.
AU - Burritt, Mary F.
AU - Riggs, B. Lawrence
PY - 1996
Y1 - 1996
N2 - Serum parathyroid hormone (PTH) and bone resorption increase in elderly women and contribute to age-related bone loss. Whether these abnormalities are caused by calcium deficiency resulting from age-related decreases in absorption and renal conservation is unclear. We studied 28 normal elderly women (mean ± SD, age 69.3 ± 2.7 yr) who were maintained for 3 yr on usual calcium intake levels (20.4 ± 7.2 mmol/day [815 ± 289 mg/day]; n = 15) (known as the usual calcium group) or high calcium intake levels (60.4 ± 6.5 mmol/day [2414 ± 260 mg/day]; n = 13) (known as the high calcium group) and a reference group of 12 normal young adult women (age 30.1 ± 4.4 yr), whose calcium intake was 23.0 ± 4.8 mmol/day (918 ± 193 mg/day) (known as the young group). Serum PTH was measured every 2 h, and urinary excretion of deoxypyridinoline (Dpd), a new marker for bone resorption, was measured in 4 h collections. Parathyroid gland secretory capacity was assessed during induced hypocalcemia. The mean 24 h serum PTH was 40% lower (P < 0.001), and the mean 24 h urinary Dpd was 35% lower (P < 0.005) in the high than in the usual calcium group. Mean parathyroid gland secretory capacity also was 47% lower (P < 0.005) in the high calcium group than in the usual calcium group. However, the usual calcium group had a mean 24 h serum PTH level that was 70% higher (P < 0.001) and a mean 24 h urinary Dpd level that was 30% higher (P < 0.005) than the young group, whereas the high calcium group was indistinguishable from the young group. Thus, failure of elderly women to increase their calcium intake to offset age-related increases in calcium requirement contributes substantially to their development of increased parathyroid activity and increased bone resorption, whereas a high calcium intake can reverse both abnormalities.
AB - Serum parathyroid hormone (PTH) and bone resorption increase in elderly women and contribute to age-related bone loss. Whether these abnormalities are caused by calcium deficiency resulting from age-related decreases in absorption and renal conservation is unclear. We studied 28 normal elderly women (mean ± SD, age 69.3 ± 2.7 yr) who were maintained for 3 yr on usual calcium intake levels (20.4 ± 7.2 mmol/day [815 ± 289 mg/day]; n = 15) (known as the usual calcium group) or high calcium intake levels (60.4 ± 6.5 mmol/day [2414 ± 260 mg/day]; n = 13) (known as the high calcium group) and a reference group of 12 normal young adult women (age 30.1 ± 4.4 yr), whose calcium intake was 23.0 ± 4.8 mmol/day (918 ± 193 mg/day) (known as the young group). Serum PTH was measured every 2 h, and urinary excretion of deoxypyridinoline (Dpd), a new marker for bone resorption, was measured in 4 h collections. Parathyroid gland secretory capacity was assessed during induced hypocalcemia. The mean 24 h serum PTH was 40% lower (P < 0.001), and the mean 24 h urinary Dpd was 35% lower (P < 0.005) in the high than in the usual calcium group. Mean parathyroid gland secretory capacity also was 47% lower (P < 0.005) in the high calcium group than in the usual calcium group. However, the usual calcium group had a mean 24 h serum PTH level that was 70% higher (P < 0.001) and a mean 24 h urinary Dpd level that was 30% higher (P < 0.005) than the young group, whereas the high calcium group was indistinguishable from the young group. Thus, failure of elderly women to increase their calcium intake to offset age-related increases in calcium requirement contributes substantially to their development of increased parathyroid activity and increased bone resorption, whereas a high calcium intake can reverse both abnormalities.
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U2 - 10.1210/jc.81.5.1699
DO - 10.1210/jc.81.5.1699
M3 - Article
C2 - 8626819
AN - SCOPUS:0030012089
SN - 0021-972X
VL - 81
SP - 1699
EP - 1703
JO - Journal of Clinical Endocrinology and Metabolism
JF - Journal of Clinical Endocrinology and Metabolism
IS - 5
ER -