Hulley S B, Vogel J M, Donaldson C L, Bayers J H, Friedman R J, Rosen S N
J Clin Invest. 1971 Dec;50(12):2506-18. doi: 10.1172/JCI106751.
Five healthy young men were studied during 24-30 wk of continuous bed rest. During the first 12 wk of bed rest, untreated subjects increased calcium excretion in the urine by 109 mg/day and in the feces by 147 mg/day. The rate of total body calcium loss was 0.5-0.7% per month. Losses of central calcaneus mineral, assessed by gamma ray transmission scanning, occurred at a tenfold higher rate, whereas the mineral content of the radius did not change. Changes in phosphorus balance resembled the calcium pattern, and increased excretion of nitrogen and hydroxyproline also occurred during bed rest. Upon reambulation, the subjects' calcium balance became positive in 1 month and recovery of their calcaneus mineral was complete within 10-20 wk. Treatment with potassium phosphate supplements (1327 mg P/day) entirely prevented the hypercalciuria of bed rest, but fecal calcium tended to increase. During the first 12 wk, calcium balance was slightly less negative (mean - 193 mg/day) than during bed rest without added phosphate (mean - 267 mg/day). This effect was not seen during the second 12 wk of bed rest. The patterns of magnesium excretion were similar to those of calcium. Fecal and urinary phosphorus excretions were doubled, and phosphorus balance became positive (+ 113 mg/day). Mineral loss from the central calcaneus was similar to that of untreated subjects. It is concluded that this form of phosphate supplementation reduces urinary calcium excretion but does not prevent bone loss during bed rest.
对5名健康年轻男性进行了为期24 - 30周的持续卧床休息研究。在卧床休息的前12周，未治疗的受试者尿钙排泄量增加了109毫克/天，粪钙排泄量增加了147毫克/天。全身钙流失率为每月0.5 - 0.7%。通过伽马射线透射扫描评估，跟骨中部矿物质流失速度高出10倍，而桡骨矿物质含量没有变化。磷平衡的变化与钙模式相似，卧床休息期间氮和羟脯氨酸的排泄也增加。重新行走后，受试者的钙平衡在1个月内变为正值，跟骨矿物质在10 - 20周内完全恢复。补充磷酸钾（1327毫克磷/天）可完全预防卧床休息引起的高钙尿症，但粪钙有增加趋势。在最初的12周内，钙平衡的负值略小于未添加磷酸盐的卧床休息期间（平均 - 193毫克/天对平均 - 267毫克/天）。在卧床休息的第二个12周期间未观察到这种效果。镁排泄模式与钙相似。粪磷和尿磷排泄量增加一倍，磷平衡变为正值（+ 113毫克/天）。跟骨中部的矿物质流失与未治疗的受试者相似。结论是，这种形式的磷酸盐补充可减少尿钙排泄，但不能预防卧床休息期间的骨质流失。
