Ijaz Sardar H, Jamal Shakeel M, Qayyum Rehan
Internal Medicine, Oklahoma University of Health Sciences, Oklahoma City, USA.
Internal Medicine, Central Michigan University College of Medicine, Saginaw, USA.
Cureus. 2018 Oct 8;10(10):e3421. doi: 10.7759/cureus.3421.
Background The hormones of the hypophysis-thyroid axis (HTA), thyroid stimulating hormone (TSH), and thyroid hormones, L-thyroxine (T4) and 3, 3', 5-L-triiodothyronine (T3), modulate the metabolism, differentiation, and proliferation of almost every cell in the body. Several studies have examined the effect of HTA hormones on platelet count and mean platelet volume (MPV), but have reported inconsistent results. Our aim was to examine the association between HTA hormones and platelet count and MPV in a large cohort of the adult population of the United States. Methods We used the continuous National Health and Nutritional Examination Survey (NHANES) which made available data on HTA hormones (1999-2000, 2001-2002, 2007-2008, 2009-2010, and 2011-2012) to examine the association between HTA hormones and platelet count and MPV. Analyses were performed with adjustments for the complex survey sampling methods of NHANES data. Unadjusted and adjusted generalized linear regressions were performed to examine the relationship between HTA hormones and platelet count and MPV. Regression models were adjusted for age, sex, race, alcohol use, smoking status, serum c-reactive protein, red blood cell folate, diabetes mellitus, glomerular filtration rate, body mass index, and hypertension. Results Of the 10,619 individuals eligible for inclusion in the analyses, 5,267 (49.6%) were females and 2,132 (20.08%) were African Americans. The mean ± standard deviation of platelet count was 256.4 ± 67.1 10/L, MPV 8.04 ± 0.92 fL, serum T4 7.92 ± 1.68 mg/dL, and serum T3 114.08 ± 24.6 ng/dL. In unadjusted analyses, an increase in the serum levels of T4 or T3 was associated with a significant increase in the platelet count and MPV (all -values < 0.05). In contrast, an increase in serum TSH level was associated with a significant decrease in the platelet count (-value = 0.05) but had no effect on MPV. After adjustment for potential confounders, serum T4 levels were significantly associated with platelet count but not with MPV. Individuals in the lowest quartile of T4 had 18.73 x 10/L lower platelet count than individuals in the upper-most quartile (-value = 0.03). Serum TSH and serum T3 levels had no effect on platelet count or MPV after adjusting for potential confounding variables. Conclusions We report that only serum T4 levels, and not TSH or T3 levels, are independently associated with platelet count and there is no independent association between HTA hormones and MPV. Our findings suggest a possible role of serum T4 on thrombopoiesis or on platelet lifespan.
背景 垂体 - 甲状腺轴（HTA）的激素、促甲状腺激素（TSH）以及甲状腺激素——左旋甲状腺素（T4）和3,3',5 - 三碘甲状腺原氨酸（T3），调节着体内几乎每个细胞的代谢、分化和增殖。多项研究探讨了HTA激素对血小板计数和平均血小板体积（MPV）的影响，但报告结果并不一致。我们的目的是在美国成年人群的大型队列中研究HTA激素与血小板计数及MPV之间的关联。
方法 我们使用连续的国家健康和营养检查调查（NHANES）（1999 - 2000年、2001 - 2002年、2007 - 2008年、2009 - 2010年以及2011 - 2012年）的数据来研究HTA激素与血小板计数及MPV之间的关联。分析针对NHANES数据的复杂调查抽样方法进行了调整。进行了未调整和调整后的广义线性回归，以研究HTA激素与血小板计数及MPV之间的关系。回归模型针对年龄、性别、种族、饮酒情况、吸烟状况、血清C反应蛋白、红细胞叶酸、糖尿病、肾小球滤过率、体重指数和高血压进行了调整。
结果 在符合纳入分析条件的10619名个体中，5267名（49.6%）为女性，2132名（20.08%）为非裔美国人。血小板计数的平均值±标准差为256.4±67.1×10⁹/L，MPV为8.04±0.92 fL，血清T4为7.92±1.68μg/dL，血清T3为114.08±24.6 ng/dL。在未调整分析中，血清T4或T3水平升高与血小板计数和MPV显著增加相关（所有P值<0.05）。相比之下，血清TSH水平升高与血小板计数显著降低相关（P值 = 0.05），但对MPV无影响。在对潜在混杂因素进行调整后，血清T4水平与血小板计数显著相关，但与MPV无关。T4处于最低四分位数的个体比最高四分位数的个体血小板计数低18.73×10⁹/L（P值 = 0.03）。在调整潜在混杂变量后，血清TSH和血清T3水平对血小板计数或MPV均无影响。
结论 我们报告，仅血清T4水平而非TSH或T3水平与血小板计数独立相关，且HTA激素与MPV之间不存在独立关联。我们的研究结果提示血清T4在血小板生成或血小板寿命方面可能发挥作用。
