Department of Endocrinology and Metabolism, Chosun University Hospital, Gwangju, Republic of Korea.
Thyroid. 2013 Jan;23(1):31-7. doi: 10.1089/thy.2012.0033. Epub 2012 Nov 15.
A possible prothrombotic effect of elevated thyrotropin (TSH) has been suggested. The mean platelet volume (MPV), which is used to measure the platelet size, can reflect platelet activity. Although limited and inconsistent data regarding the effects of thyroid function on the MPV are available from small-scale case-control studies, no study has been based on a general population, particularly in euthyroid states. The objective of the present study was to determine whether there is an association between the MPV and serum TSH concentrations in an apparently healthy Korean population without overt thyroid disease, but including subjects with unsuspected subclinical hypothyroidism (SCH).
We retrospectively studied 6893 asymptomatic Korean adults who were 20 years of age or older and who underwent voluntary regular health check-ups at the Health Promotion Center of Chosun University Hospital. The subjects who met the inclusion and exclusion criteria were subdivided into four groups, such as tertile groups for the TSH reference range and an SCH (TSH ≥4 μIU/mL with a normal free T4 concentration) group according to the TSH level. We compared the mean values of the MPVs among the groups. Multivariate logistic regression analyses were used to identify associations between the highest tertile of the MPV and the TSH subgroups.
The mean level of the MPV in all study subjects was 8.12±0.75 femtoliters (fL), and the mean value of the MPV was significantly different in each group. The mean MPV in SCH was significantly higher compared with those of the first tertile (T1) and second tertile (T2). Moreover, the mean MPV increased statistical significantly by increasing tertiles of the TSH concentration and was highest in SCH (T1, 8.08±0.81 fL; T2, 8.09±0.62 fL; T3, 8.13±0.77 fL; SCH, 8.21±0.81 fL; p for trend=0.012). After adjusting for risk factors associated with increasing MPVs and platelet counts, SCH was independently associated with the highest tertile of the MPV (all subjects, odds radio (OR) 1.58 [95% confidence interval (CI) 1.19-2.09]; men, OR 1.70 [CI 1.10-2.64]; women, OR 1.55 [CI 1.06-2.26]).
The MPV was positively correlated with the TSH level. SCH is an independently associated factor with the highest tertile of MPV in a general Korean population. We propose that the MPV may contribute to the prothrombotic condition that is associated with SCH and perhaps even in putative euthyroid states where the TSH level is the higher part of the normal range.
促甲状腺激素（TSH）升高可能存在促血栓形成作用。血小板平均体积（MPV）用于测量血小板大小，可以反映血小板活性。虽然小型病例对照研究提供了关于甲状腺功能对MPV 影响的有限且不一致的数据，但尚无研究基于一般人群，特别是在甲状腺功能正常的人群中进行。本研究旨在确定在无明显甲状腺疾病的情况下，甲状腺功能正常的韩国人群中，MPV 是否与血清 TSH 浓度有关，包括亚临床甲状腺功能减退症（SCH）患者。
我们回顾性研究了 6893 名年龄在 20 岁或以上且在朝鲜大学医院健康促进中心进行自愿定期健康检查的无症状韩国成年人。根据 TSH 水平，将符合纳入和排除标准的受试者分为四组，如 TSH 参考范围的三分位组和 SCH（TSH≥4μIU/ml 且游离 T4 浓度正常）组。我们比较了各组之间的 MPV 平均值。使用多变量逻辑回归分析来确定 MPV 最高三分位与 TSH 亚组之间的关联。
所有研究对象的平均 MPV 水平为 8.12±0.75 飞升（fL），并且每个组的 MPV 值均存在显著差异。SCH 的平均 MPV 明显高于第一三分位（T1）和第二三分位（T2）。此外，随着 TSH 浓度三分位的增加，MPV 呈统计学显著增加，且在 SCH 中最高（T1：8.08±0.81fL；T2：8.09±0.62fL；T3：8.13±0.77fL；SCH：8.21±0.81fL；p 趋势=0.012）。在校正与 MPV 和血小板计数增加相关的危险因素后，SCH 与 MPV 的最高三分位独立相关（所有受试者，优势比（OR）1.58（95%置信区间（CI）1.19-2.09）；男性，OR 1.70（CI 1.10-2.64）；女性，OR 1.55（CI 1.06-2.26））。
MPV 与 TSH 水平呈正相关。SCH 是一般韩国人群中与 MPV 最高三分位相关的独立相关因素。我们提出，MPV 可能导致与 SCH 相关的促血栓形成状态，甚至可能导致 TSH 水平处于正常范围较高部分的潜在甲状腺功能正常状态。
