Sorva A, Välimäki M, Risteli J, Risteli L, Elfving S, Takkunen H, Tilvis R
Koskela Hospital, Helsinki, Finland.
Eur J Clin Invest. 1994 Dec;24(12):806-12. doi: 10.1111/j.1365-2362.1994.tb02023.x.
Chronic immobilization could markedly affect calcium and bone metabolism in elderly people. To investigate this, and to test the theory of 'type II' osteoporosis in bedridden elderly patients with low vitamin D status, 55 such subjects were examined. Serum concentrations of ionized calcium (Ca++), intact parathyrin (PTH) and two novel markers of bone collagen formation (carboxyterminal propeptide of type I procollagen; PICP) and resorption (carboxyterminal crosslinked telopeptide of type I collagen; ICTP) were measured. The effects on these parameters after 40 weeks of supplementation with vitamin D (1000 IU d-1) and/or calcium (1 g d-1) were subsequently prospectively evaluated. Despite low (mean 11.6 nmoll-1) serum 25-hydroxyvitamin D levels (25-OHD), those of 1,25-dihydroxy-vitamin D (1,25-(OH)2D) were mostly normal. Neither correlated with Ca++ or PTH. PTH correlated negatively not only with Ca++ (r = -0.328, P < 0.05) but also with ICTP (r = -0.306, P < 0.05). Mean PICP was normal but ICTP was elevated and tended to correlate positively with Ca++ (r = 0.268, P = 0.06). Vitamin D supplementation did not change PICP or ICTP considerably, despite slightly increased 1,25-(OH)2D and slightly decreased PTH. Ca++ values were normal and remained stable. In conclusion, Ca++ and PTH are poor indicators of vitamin D status in chronically immobilized elderly subjects. Furthermore, the results suggest that the increased bone resorption is not due to 'type II' secondary hyperparathyroidism; rather the resorption is primarily increased. Correction of vitamin D deficiency does not seem to benefit ageing bones unless adequate mechanical loading is provided.
长期固定不动会显著影响老年人的钙和骨代谢。为了对此进行研究，并验证维生素D水平较低的卧床老年患者中“II型”骨质疏松症的理论，对55名此类受试者进行了检查。测量了血清离子钙（Ca++）、完整甲状旁腺素（PTH）以及两种新的骨胶原形成标志物（I型前胶原羧基末端前肽；PICP）和骨吸收标志物（I型胶原羧基末端交联端肽；ICTP）的浓度。随后前瞻性评估了补充维生素D（1000 IU/天）和/或钙（1克/天）40周后对这些参数的影响。尽管血清25-羟维生素D（25-OHD）水平较低（平均11.6 nmol/L），但1,25-二羟维生素D（1,25-(OH)2D）水平大多正常。两者均与Ca++或PTH无相关性。PTH不仅与Ca++呈负相关（r = -0.328，P < 0.05），还与ICTP呈负相关（r = -0.306，P < 0.05）。平均PICP正常，但ICTP升高，且倾向于与Ca++呈正相关（r = 0.268，P = 0.06）。尽管1,25-(OH)2D略有升高且PTH略有降低，但补充维生素D并未使PICP或ICTP有显著变化。Ca++值正常且保持稳定。总之，在长期固定不动的老年受试者中，Ca++和PTH并非维生素D状态的良好指标。此外，结果表明骨吸收增加并非由于“II型”继发性甲状旁腺功能亢进；而是骨吸收主要增加。除非提供足够的机械负荷，纠正维生素D缺乏似乎对老化骨骼并无益处。
