Diekman M J, van der Put N M, Blom H J, Tijssen J G, Wiersinga W M
Department of Endocrinology & Metabolism, Academic Medical Center, University of Amsterdam, The Netherlands.
Clin Endocrinol (Oxf). 2001 Feb;54(2):197-204. doi: 10.1046/j.1365-2265.2001.01170.x.
Hyperhomocysteinaemia is a risk factor for premature atherosclerotic vascular disease and venous thrombosis. The aim of the present study was to assess plasma total homocysteine (tHCys) concentrations in hypo- as well as hyperthyroid patients before and after treatment, and to evaluate the role of potential determinants of plasma tHCys levels in these patients.
Prospective follow up study.
Fifty hypothyroid and 46 hyperthyroid patients were studied in the untreated state and again after restoration of euthyroidism.
Fasting plasma levels of tHCys and its putative determinants (plasma levels of free thyroxine (fT4), folate, vitamin B(12), renal function, sex, age, smoking status and the C677T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene were measured before and after treatment.
Restoration of the euthyroid state decreased both tHCys (17.6 +/- 10.2-13.0 +/- 4.7 micromol/l; P < 0.005) and creatinine (83.9 +/- 22.0-69.8 +/- 14.2 micromol/l; P < 0.005) in hypothyroid patients and increased both tHCys (10.7 +/- 2.5-13.4 +/- 3.3 micromol/l; P < 0.005) and creatinine (49.0 +/- 15.4-66.5 +/- 15.0 micromol/l; P < 0.005) in hyperthyroid patients (values as mean +/- SD). Folate levels were lower in the hypothyroid group compared to the hyperthyroid group (11.7 +/- 6.4 and 15.1 +/- 7.6 nmol/l; P < 0.05). Pretreatment tHCys levels correlated with log fT(4) (r = - 0.47), folate (r = - 0.21), plasma creatinine (r = 0.45) and age (r = 0.35) but not with C677T genotype. Multivariate analysis indicated that pretreatment log(fT(4)) levels and age accounted for 28% the variability of pre-treatment tHCys (tHCys = 14.2-5.50 log(fT(4)) + 0.14 age). After treatment the logarithm of the change (Delta) in fT(4) (expressed as the post-treatment fT(4)/pre-treatment fT(4) ratio) accounted for 45% of the variability in change of tHCys ( tHCys = - 0.07-4.94 log ( fT(4))); there was no independent contribution of changes in creatinine which was, however, strongly related to changes in tHCys (r = 0.61).
Plasma tHCys concentrations increased in hypothyroidism and decreased in hyperthyroidism. Plasma fT(4) is an independent determinant of tHCys concentrations. Lower folate levels and a lower creatinine clearance in hypo-thyroidism, and a higher creatinine clearance in hyperthyroidism only partially explain the changes in tHCys.
高同型半胱氨酸血症是早发性动脉粥样硬化性血管疾病和静脉血栓形成的危险因素。本研究的目的是评估甲状腺功能减退和甲状腺功能亢进患者治疗前后的血浆总同型半胱氨酸（tHCys）浓度，并评估这些患者血浆tHCys水平潜在决定因素的作用。
前瞻性随访研究。
对50例甲状腺功能减退患者和46例甲状腺功能亢进患者在未治疗状态下进行研究，并在恢复甲状腺功能正常后再次进行研究。
在治疗前后测量空腹血浆tHCys水平及其假定的决定因素（游离甲状腺素（fT4）、叶酸、维生素B12的血浆水平、肾功能、性别、年龄、吸烟状况以及亚甲基四氢叶酸还原酶（MTHFR）基因中的C677T多态性）。
甲状腺功能减退患者甲状腺功能恢复正常后，tHCys（17.6±10.2 - 13.0±4.7 μmol/L；P < 0.005）和肌酐（83.9±22.0 - 69.8±14.2 μmol/L；P < 0.005）均降低；甲状腺功能亢进患者甲状腺功能恢复正常后，tHCys（10.7±2.5 - 13.4±3.3 μmol/L；P < 0.005）和肌酐（49.0±15.4 - 66.5±15.0 μmol/L；P < 0.005）均升高（数值为平均值±标准差）。甲状腺功能减退组的叶酸水平低于甲状腺功能亢进组（11.7±6.4和15.1±7.6 nmol/L；P < 0.
