Study of thyroid hormone level in mild cognitive impairment dysfunction patients in Xinjiang Uygur and Han nationalities

Objective To investigate the level of thyroid hormone in Xinjiang Uygur and Han old people with mild cognitive dysfunction (MCI), and to provide basis for early intervention of MCI. Methods Case control study was carried out among 5398 residents who was above 60 years old in Xinjiang, Han and Uyghur ,from July 2008 to October 2010.According to the diagnosis of MCI by American Psychiatric Society and DSM-Ⅳ, 314 patients were diagnosed with MCI matching 299 healthy people as control group.Serum T3 (triiodothyronine), T4 (thyroxine) and TSH (thyroid stimulating hormone) level was determined and compared between control group and MCI group with different nationalities and genders SPSS 17.0 statistical software was used to depict median and quartile of the data, two groups of distribution between the location of the median use Wilcoxon compares the rank of testing and analysis. Results (1) the level of serum T3 in MCI group was lower than that of the control group (1.26 μg/L vs.1.28 μg/L, Z=2.41, P<0.05), serum TSH level of MCI group was 5.37 mIU/L higher than that of the control group (Z=4.13, P<0.05). (2) Male serum TSH level of MCI was 5.74 mIU/L higher than that of the control group (Z=5.09, P<0.05).Women serum T3 level of MCI was 1.29 μg/L lower than that of the control group 1.53 μg/L (Z=2.62, P<0.05). (3) Serum TSH level of MCI in Han nationality was 6.79 mIU/L higher than that of the control group (Z=4.95, P<0.05).Serum T3 level of MCI in Uygur nationality was 1.29 μg/L lower than those of the control group 1.39 μg/L (Z=2.58, P<0.05), and T4 level was 82.37 μg/L lower than that of the control group 92.71 μg/L (Z=4.28, P<0.05).(4) Uygur′s T4 level was 82.3 μg/L, higher than the 42.12 μg/L in Han nationality (Z=9.83, P<0.05), level of TSH in Uygur with MCI was 6.79 lower than that of the Han nationality (Z=4.28, P<0.05). (5) The unconditional Logistic regression analysis showed hypertension, sugar metabolism disorders, hyperlipidemia, low level of T3 were independent risk factors for MCI (OR values were 2.014, 2.466, 2.096, 0.470，respectively, 95% CI were 1.361-2.981, 1.649-3.687, 1.396-3.149, 0.334-0.663, respectively, P<0.05). Conclusions (1) Thyroid hormone level in old people related to the occurrence of MCI；(2) Aside recognized independent risk factors for MCI as hypertension, sugar metabolism disorders, hyperlipidemia, low T3 level may be one of the MCI independent risk factors.（Chin J Lab Med，2012,35：921-925） Key words: Cognition disorders; Thyroid hormones; Aged