Sita-Lumsden A, Lapthorn G, Swaminathan R, Milburn H J
Department of Respiratory Medicine, Guy's and St Thomas' Foundation Trust, London, UK.
Thorax. 2007 Nov;62(11):1003-7. doi: 10.1136/thx.2006.070060. Epub 2007 May 25.
As well as its role in the regulation of calcium metabolism, vitamin D is an immunoregulatory hormone. Epidemiological evidence also suggests a link between vitamin D deficiency and tuberculosis (TB). A study was undertaken to examine serum vitamin D concentrations before treatment in patients with active TB and their contacts from the same ethnic and social background and to investigate the relative contributions of diet and sunlight exposure.
Serum vitamin D concentrations were measured before treatment in 178 patients with active TB and 130 healthy contacts. The prevalence of vitamin D deficiency and its relation to skin colour, month of estimation and TB diagnosis were determined. 35 patients and 35 frequency-matched contacts completed dietary and sun exposure questionnaires to determine the relative contribution of these to serum vitamin D concentrations.
There was a statistically significant difference in serum vitamin D concentrations between patients and contacts (20.1 vs 30.8 nmol/l, 95% CI 7.1 to 14.3; p<0.001) and significantly more patients had severely deficient concentrations (<21 nmol/l) than controls (114/178 (64%) vs 40/130 (31%), p<0.001). There was no association between serum concentrations of vitamin D and skin pigmentation. The healthy contacts showed a predictable seasonal pattern, rising to peak concentrations in the summer months, but this response was absent in patients with TB. Dietary intake was the same in both patients with TB and contacts matched for age, sex and skin colour, but patients with TB displayed a stronger correlation between serum vitamin D concentrations and dietary intake (r = 0.42, p = 0.016) than controls (r = 0.13, p>0.1). There was no difference in sunlight exposure between the groups.
Patients with active TB have lower serum vitamin D concentrations than contacts from similar ethnic and social backgrounds and with comparable dietary intake and sun exposure, and do not show the expected seasonal variation. These observations indicate that other factors are contributing to vitamin D deficiency in patients with TB and suggest abnormal handling of this vitamin.
维生素D除了在钙代谢调节中发挥作用外，还是一种免疫调节激素。流行病学证据也表明维生素D缺乏与结核病（TB）之间存在联系。开展了一项研究，以检测活动性结核病患者及其来自相同种族和社会背景的接触者在治疗前的血清维生素D浓度，并调查饮食和阳光照射的相对影响。
检测了178例活动性结核病患者和130名健康接触者治疗前的血清维生素D浓度。确定了维生素D缺乏的患病率及其与肤色、检测月份和结核病诊断的关系。35例患者和35名频率匹配的接触者完成了饮食和阳光照射问卷，以确定这些因素对血清维生素D浓度的相对影响。
患者与接触者的血清维生素D浓度存在统计学显著差异（20.1对30.8nmol/L，95%CI7.1至14.3；p<0.001），且严重缺乏浓度（<21nmol/L）的患者明显多于对照组（114/178（64%）对40/130（31%），p<0.001）。血清维生素D浓度与皮肤色素沉着之间无关联。健康接触者呈现出可预测的季节性模式，在夏季月份浓度升至峰值，但结核病患者无此反应。结核病患者与年龄、性别和肤色匹配的接触者的饮食摄入量相同，但结核病患者血清维生素D浓度与饮食摄入量之间的相关性（r = 0.42，p = 0.016）强于对照组（r = 0.13，p>0.1）。两组之间的阳光照射无差异。
活动性结核病患者的血清维生素D浓度低于来自相似种族和社会背景、饮食摄入量和阳光照射相当的接触者，且未表现出预期的季节性变化。这些观察结果表明，其他因素导致了结核病患者的维生素D缺乏，并提示该维生素的处理存在异常。
