Jubiz William, Ramirez Marcela
Centro de Endocrinología, Metabolismo y Diabetes y Universidad Libre, Cali, Colombia.
J Clin Endocrinol Metab. 2014 Jun;99(6):E1031-4. doi: 10.1210/jc.2013-4360. Epub 2014 Mar 6.
Malabsorption of l-T4 is a major clinical problem. Changes in gastric pH caused by several medical illnesses are associated with difficulties in the control of patients with hypothyroidism receiving the hormone. Means to correct these alterations would be of clinical value.
Our objective was to study the effect of vitamin C on the absorption of l-T4 in patients with hypothyroidism and gastritis.
Thirty-one patients with hypothyroidism, 28 females age 47.5 ± 13.5 (mean ± SD) years and 3 males age 55.7 ± 11.2 years ingested the dose of l-T4 in 120 mL water containing or not containing 500 mg vitamin C in a solution of pH 2.9 ± 0.1 (mean ± SD). Serum concentrations of free T4 and TSH were measured at the end of 3 periods of 2 months each, 2 controls and 1 vitamin C. Serum total T3 was measured in 16 of the patients, before and at the end of the vitamin C period. Serum TSH and free T4 and T3 were measured by a solid-phase, enzyme-labeled chemiluminescent competitive immunoassay All patients had gastrointestinal pathology and were not in good control when taking l-T4 before the study, and 23 had autoimmune thyroiditis or idiopathic hypothyroidism. The median l-T4 dose was 100 μg with an interquartile range of 50 μg. The protocol was reviewed and approved by our institution's ethics committee. Patients were asked to sign a written consent to participate in the study.
Serum concentrations of TSH, free T4, and T3 improved while on vitamin C. Serum TSH decreased in all patients (control, 11.1 [10.5] μIU/mL, median [interquartile range]), vitamin C 4.2 (3.7) μIU/mL, P = .0001), and it was normalized in 17 patients (54.8%). The average decrease was 69.2%. Serum T4 was higher with vitamin C in 30 of the 31 patients (control, 1.1 [0.3] ng/dL; vitamin C, 1.3 [0.3] ng/dL; P < .0001), and serum T3 increased as well in all 16 patients in whom it was measured (control, 60.5 [16.5] ng/dL; vitamin C, 70 [21] ng/dL; P < .005).
In patients with hypothyroidism and gastrointestinal pathology, vitamin C improves the abnormalities in serum free T4, T3, and TSH concentrations. This approach is helpful in the management of these patients.
左旋甲状腺素（l-T4）吸收不良是一个主要的临床问题。多种内科疾病引起的胃pH值变化与接受该激素治疗的甲状腺功能减退患者的病情控制困难有关。纠正这些改变的方法具有临床价值。
我们的目的是研究维生素C对甲状腺功能减退合并胃炎患者l-T4吸收的影响。
31例甲状腺功能减退患者，28例女性，年龄47.5±13.5（均值±标准差）岁，3例男性，年龄55.7±11.2岁，在pH值为2.9±0.1（均值±标准差）的溶液中，于120 mL水中摄入含或不含500 mg维生素C的l-T4剂量。在每2个月的3个时间段结束时测量游离T4和促甲状腺激素（TSH）的血清浓度，2个为对照期，1个为维生素C期。16例患者在维生素C期开始前和结束时测量血清总T3。血清TSH、游离T4和T3通过固相酶标记化学发光竞争性免疫测定法进行检测。所有患者均有胃肠道病变，在研究前服用l-T4时病情控制不佳，23例患有自身免疫性甲状腺炎或特发性甲状腺功能减退。l-T4剂量中位数为100 μg，四分位间距为50 μg。该方案经我们机构的伦理委员会审查并批准。患者被要求签署书面知情同意书以参与研究。
服用维生素C期间，TSH、游离T4和T3的血清浓度有所改善。所有患者的血清TSH均下降（对照期，11.1[10.5] μIU/mL，中位数[四分位间距]），维生素C期为4.2（3.7）μIU/mL，P = 0.0001），17例患者（54.8%）恢复正常。平均下降69.2%。31例患者中有30例服用维生素C时血清T4升高（对照期，1.1[0.3] ng/dL；维生素C期，1.3[0.3] ng/dL；P < 0.0001），所有16例测量血清T3的患者血清T3也升高（对照期，60.5[16.5] ng/dL；维生素C期，70[21] ng/dL；P < 0.005）。
在甲状腺功能减退合并胃肠道病变的患者中，维生素C可改善血清游离T4、T3和TSH浓度的异常。这种方法有助于这些患者的管理。
