Wastney M E, Henkin R I
Georgetown University Medical Center, Washington, D.C. 20007.
J Nutr. 1989 Oct;119(10):1438-43. doi: 10.1093/jn/119.10.1438.
Zinc absorption is often determined following oral administration of tracer by fecal monitoring as dose minus tracer excreted in feces. The value obtained for absorption with this method is influenced by excretion of absorbed tracer into feces during the fecal collection period and by any incomplete elimination of unabsorbed tracer. In the present study a published, physiologically based compartmental model of zinc metabolism has been used to calculate, after oral tracer administration, the fecal appearance of unabsorbed and absorbed tracer and the appearance when fractional rates of endogenous excretion and elimination were varied. Absorption was determined by fecal monitoring and compared to the value determined using parameter values of the compartmental model. The value calculated for absorption using fecal monitoring varied with length of fecal collection, rate of excretion of absorbed tracer (secretion) and rate of elimination of unabsorbed tracer. Absorption was determined correctly by fecal monitoring only when the amount of absorbed tracer excreted was equivalent to the amount of unabsorbed tracer remaining in the gut. Fecal monitoring determines a parameter representing the combined processes of absorption, endogenous excretion (or secretion) and fecal elimination.
锌的吸收通常通过口服示踪剂后监测粪便来确定，即剂量减去粪便中排出的示踪剂。用这种方法获得的吸收值受粪便收集期间吸收的示踪剂排泄到粪便中的情况以及未吸收示踪剂的任何不完全清除的影响。在本研究中，一个已发表的基于生理学的锌代谢房室模型被用于计算口服示踪剂后未吸收和吸收的示踪剂的粪便出现情况以及内源性排泄和清除的分数率变化时的出现情况。通过粪便监测确定吸收情况，并与使用房室模型参数值确定的值进行比较。使用粪便监测计算的吸收值随粪便收集时间、吸收的示踪剂排泄率（分泌）和未吸收示踪剂的清除率而变化。只有当吸收的示踪剂排泄量等于肠道中剩余的未吸收示踪剂量时，粪便监测才能正确确定吸收情况。粪便监测确定的是一个代表吸收、内源性排泄（或分泌）和粪便清除综合过程的参数。
