Mani Deepthi Dasari, Vaikkakara Suresh, Patil Avinash, Ganta Sandeep, Sachan Alok, Raghavendra Katakam, Kiranmayi Vinapamula S, Chowhan Amit Kumar
Department of Endocrinology, Sri Venkateswara Institute of Medical Sciences, Tirupati, India.
Department of Biochemistry, Sri Venkateswara Institute of Medical Sciences, Tirupati, India.
Int J Endocrinol Metab. 2021 Jan 19;19(1):e105751. doi: 10.5812/ijem.105751. eCollection 2021 Jan.
Glycated hemoglobin (HbA1c) levels are dependent not only on the average blood glucose levels over the preceding 2 - 3 months but also on the turnover of erythrocytes. Hyperthyroidism is known to be associated with an increase in erythrocyte turnover that may falsely lower the HbA1c in relation to the level of glycemia.
To assess the impact of medical correction of hyperthyroidism on HbA1c, independent of changes in the fasting plasma glucose and 2-hour post-oral glucose tolerance test plasma glucose.
Adult patients with overt hyperthyroidism (n = 36) were tested for their hemoglobin, reticulocyte percentage, HbA1c and fasting and post-oral glucose tolerance test (OGTT) 2-hour plasma glucose, both at baseline and following at least three months of near normalization of serum thyroxin on Carbimazole treatment.
Correction of hyperthyroidism in 36 patients was associated with an increase in the hemoglobin (P = 0.004) and a rise in HbA1c (P = 0.025), even though no significant change was observed in both the fasting (P = 0.28) and post OGTT two-hour plasma glucose (P = 0.54). Also, the proportion of patients with HbA1c ≥ 5.7% rose from 3/36 to 10/36; P = 0.016, while the proportion of patients with either abnormal fasting or abnormal post OGTT 2-hour plasma glucose or both did not show any significant change (P = 0.5). The sensitivity of HbA1c to diagnose prediabetes increased from 20% to 50% post- treatment.
Glycated hemoglobin is falsely low in relation to glycemia in patients with untreated hyperthyroidism.
糖化血红蛋白（HbA1c）水平不仅取决于前2至3个月的平均血糖水平，还取决于红细胞的更新率。已知甲状腺功能亢进与红细胞更新率增加有关，这可能会使HbA1c相对于血糖水平被错误地降低。
评估甲状腺功能亢进的药物治疗对HbA1c的影响，独立于空腹血糖和口服葡萄糖耐量试验2小时血糖的变化。
对36例显性甲状腺功能亢进成年患者在基线时以及使用卡比马唑治疗使血清甲状腺素接近正常至少三个月后，检测其血红蛋白、网织红细胞百分比、HbA1c以及空腹和口服葡萄糖耐量试验（OGTT）2小时血糖。
36例患者甲状腺功能亢进的纠正与血红蛋白增加（P = 0.004）和HbA1c升高（P = 0.025）相关，尽管空腹血糖（P = 0.28）和OGTT后2小时血糖（P = 0.54）均未观察到显著变化。此外，HbA1c≥5.7%的患者比例从3/36升至10/36；P = 0.016，而空腹或OGTT后2小时血糖异常或两者均异常的患者比例未显示任何显著变化（P = 0.5）。治疗后HbA1c诊断糖尿病前期的敏感性从20%提高到50%。
未经治疗的甲状腺功能亢进患者的糖化血红蛋白相对于血糖水平被错误地低估。
