Free and protein-bound cobalamin absorption in healthy middle-aged and older subjects
Free and protein-bound cobalamin absorption in healthy middle-aged and older subjects
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DOI：
10.1111/j.1532-5415.1996.tb01866.x
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发表时间：
1996-08-01
影响因子：
6.3
通讯作者：
Hoefnagels, WH
中科院分区：
文献类型：
--
作者：
vanAsselt, DZ;vandenBroek, WJ;Hoefnagels, WH
目的：研究健康中老年受试者游离态和蛋白结合态钴胺的吸收及其与萎缩性胃炎的相关性。设计：一项横断面研究。中年受试者被定义为年龄小于65岁的人(中位年龄为57岁)，年龄在65岁以上的受试者(中位年龄为75岁)。测量：口服炒鸡蛋黄后，用48小时尿排出法测定蛋白结合钴胺的吸收，通过向母鸡注射钴-57-氰基钴胺在体内标记钴-57-钴胺。钴-57-钴胺与蛋白质的结合率为65%。口服结晶钴-57-氰基钴胺后48小时尿排泄法测定游离钴胺吸收。结果：中年组蛋黄Co-57-钴胺尿液中位数为12.3%(第25和75百分位数10.5%~14.5%)，老年组为11.7%(第25和75百分位数9.8%~13.6%)。中年受试者服用Co-57-钴胺后尿液中位数为25.7%(第25和第75百分位数20.6%~30.7%)，而老年组为27.9%(第25和75百分位数21.4%~34.5%)(P=.694)。蛋黄和游离钴-57-钴胺排泄量与年龄无关。13名受试者胃蛋白酶原A/C比值小于1.6，提示萎缩性胃炎。萎缩性胃炎组中，11例胃蛋白酶原A浓度大于或等于17微克/L，提示轻度至中度萎缩性胃炎，2例胃蛋白酶原A浓度小于17微克/L，提示重度萎缩性胃炎或胃萎缩。所有受试者的空腹血浆胃泌素浓度均正常。与非萎缩性胃炎组相比，萎缩性胃炎组的游离钴和蛋黄钴-57-钴胺排泄量并没有减少，中位血浆钴胺浓度在老年人中也没有显著降低(P=.205)。尽管如此，血浆钴胺浓度与年龄呈负相关(r=-.36；P=.008)。结论：我们发现健康中年人和老年人在游离态或蛋白质结合态钴胺吸收方面没有显著差异。此外，在被确认为轻度至中度萎缩性胃炎的受试者中，没有发现钴胺吸收的变化。因此，根据我们的结果，低钴胺水平在老年人中的高发生率既不能用衰老过程解释，也不能用轻到中度萎缩性胃炎来解释。
OBJECTIVE: To study free- and protein-bound cobalamin absorption and the correlation with atrophic gastritis in healthy middle-aged and older subjects.DESIGN: A cross-sectional study.PARTICIPANTS: Fifty-two healthy subjects, aged 26 to 87 years, apparently free from conditions known to influence the cobalamin status. Middle-aged subjects were defined as those younger than 65 years of age (median age 57 years) and older subjects as those 65 years and older (median age 75 years).MEASUREMENTS: Protein-bound cobalamin absorption was assessed by 48-hour urinary excretion method following oral administration of scrambled egg yolk, labeled in vivo with Co-57-cobalamin by injecting a hen with Co-57-cyanocobalamin. The percentage of Co-57-cobalamin bound to protein was 65%. Free cobalamin absorption was assessed by 48-hour urinary excretion method following oral administration of crystalline Co-57-cyanocobalamin. Plasma cobalamin, folate and fasting plasma gastrin, and pepsinogen A and C concentrations were determined.RESULTS: The median urinary excretion of egg yolk Co-57-cobalamin in middle-aged subjects was 12.3% (25th and 75th percentiles 10.5%-14.5%) compared with 11.7% (25th and 75th percentiles 9.8%-13.6%) in older subjects (P = .283). The median urinary excretion after administration of free Co-57-cobalamin in middle-aged subjects was 25.7% (25th and 75th percentiles 20.6%-30.7%) compared with 27.9% (25th and 75th percentiles 21.4%-34.5%) in older subjects (P = .694). Neither egg yolk nor free Co-57- cobalamin excretion correlated with age.A ratio of pepsinogen A to pepsinogen C less than 1.6, indicating atrophic gastritis, was found in 13 subjects. Within the atrophic gastritis group, 11 subjects had a pepsinogen A concentration greater than or equal to 17 mu g/L, indicating mild to moderate atrophic gastritis, and two subjects had a pepsinogen A concentration less than 17 mu g/L, indicating severe atrophic gastritis or gastric atrophy. All subjects had normal fasting plasma gastrin concentrations. Free and egg yolk Co-57-cobalamin excretions were not reduced in the atrophic gastritis group when compared with the non-atrophic gastritis group.Median plasma cobalamin concentration was not significantly lower in older subjects (P = .205). Nonetheless, plasma cobalamin concentration correlated negatively with age (r = -.36; P = .008).CONCLUSIONS: We demonstrated no significant difference in either free or protein-bound cobalamin absorption between healthy middle-aged and older adults. In addition, no alteration in cobalamin absorption was found in subjects identified as having mild to moderate atrophic gastritis. Therefore, based on our results, the high prevalence of low cobalamin levels in older people cannot be explained by either the aging process or mild to moderate atrophic gastritis.