THYROID STATUS COMPENSATION AND CARDIOVASCULAR PARAMETERS IN PATIENTS WITH PRIMARY HYPOTHYREOSIS

Aim. To investigate the effects of primary hypothyreosis (PHT) compensation on cardiac remodelling, aortic elasticity, and vasomotor endothelial function. 

Material and methods. In total, 28 women with PHT were examined (age 42–78 years; median age 59,5 years). All patients underwent echocardiography and the assessment of aortic elasticity and vasomotor endothelial function using the method by Cleremajer et al. (1992). The examination took place twice, during the PHT decompensation and its compensation due to the treatment with levothyroxine sodium (on average, 3 months after the beginning of the therapy). 

Results. The PHT compensation was associated with a reduction in the levels of thyrotrophic hormone from 18,8 (95% confidence interval 10,7–27,0) to 2,6 (2,1–3,1) mIU/l (p<0,001) and an elevation in the levels of free thyroxin from 10,8 (9,2–12,44) to 13,7 (12,7–14,7) pmol/l (p<0,005). Left ventricular myocardial mass decreased from 192,4 (182,0–202,8) to 171,4 (160,9–181,9) g. The proportion of patients with left ventricular diastolic dysfunction decreased from 92,9 (77,4–98,0) to 71,4 (54,7–88,2)% (p<0,05), while the proportion of patients with right ventricular diastolic dysfunction decreased from 82,1 (64,4–92,1) to 25,0 (9,0–41,0)% (p<0,001). Aortic wall thickness reduced from 5,26 (4,90–5,62) to 4,53 (4,28–4,78) mm, aortic elasticity index increased from 2,26 (1,60–2,92) to 5,26 (4,36–6,15) mm 2/mm Hg, and pulse wave velocity decreased from 12,8 (11,4–14,3) to 8,42 (6,59–10,3) m/s. Relative increase in brachial artery diameter in the reactive hyperemia test, as a marker of vasomotor endothelial function, changed from 2,91 (1,69–4,14) to 9,13 (7,84–10,4)% (all p-values <0,001). 

Conclusion. PHT compensation is associated with reduced left ventricular myocardial mass, improved left and right ventricular function, increased aortic elasticity, and improved vasomotor endothelial function.

1. Fazio S, Palmiri EA, Lombardi G.et al. Effect of thyroid hormone on the cardiovascular system. Rec Progr Horm Recearch 2004; 59:31–50.

2. Klein I, Danzy S Thyroid disease and the heart. Circulat 2007; 116:1725–35.

3. Xiang G, He Y, Zhao L et al. Impairment of endothelium-dependent arterial dilation in Hashimoto´s thyroiditis patients with euthyroidism. Clin Endocrinol 2006; 64 (6):698–702.

4. Clausen P, Mersebach H, Nielsen B et al. Hypothyroidism is associated with signs of endothelial dysfunction despite 1-year replacement therapy with levothyroxine. Clin Endocrinol 2009; 70 (6):932–7.

5. Cabral MD, Teixeira PF, Silva NA et al. Normal flow-mediated vasodilatation of the brachial artery and carotid artery intima-media thickness in subclinical hypothyroidism. Braz J Med Biol Res 2009; 42 (5):426–32.

6. Chang HJ, Kim KW, Choi SH et al. Endothelial function is not changed during shortterm withdrawal of thyroxine in patients with differentiated thyroid cancer and low cardiovascular risk. Yonsei Med J 2010; 51 (4):492–8.

7. Tomita M, Masuda H, Sumi T et al. Estimation of right ventricular volume by modified echocardiographic subtraction method. Am Heart J 1992; 123:1011.

8. Rudski LG, Wyman WL, Afilalo J et al. Guidelines for the Echocardiographic Assessment of the Right Heart in Adults: A Report from the America Society of Echocardiography. J Am Soc Echocardiogr 2010; 23:685–713.

9. Andreevskaja MV, Chihladze NM, Saidova MA Aortic Stiffness Ultrasound Assessment in Cardiovascular Pathology. Ultrasonic diagnostics 2009; 2:91–9. Russian (Андреевская М. В., Чихладзе Н. М., Саидова М. А. Возможности ультразвуковой оценки ригидности аорты и ее значимость при патологии сердца и сосудов. Ультразвуковая диагностика 2009; 2:91–9).

10. Laurent S, Cockcroft J, Van Bortel L et al. Expert consensus document on arterial stiffness: methodological issues and clinical applications. Eur Heart J 2006; 27 (21):2588–605.

11. Celermajer DS, Sorensen KE, Gooch VM et al. Non-invasive detection of endothelial dysfunction in children and adults at risk of atherosclerosis. Lancet 1992; 7:1111–5.

12. Vargas F, Moreno IM, Rodriguez–Gomez R et al. Vascular and renal function in experimental thyroid disorders. Eur J Endocrinol 2006; 154 (2):197–212.

13. Hoption Cann SA. Hypothesis: dietary iodine intake in the etiology of cardiovascular disease. J Am Coll Nutr. 2006; 25 (1):1–11.

14. Mazur ES, Kilejnikov DV, Orlov JuA et al. Pathogenesis of hypertension in patients with primary hypothyroidism. Arterial Hypertension 2012; 1 (18):58–61. Russian (Мазур Е. С., Килейников Д. В., Орлов Ю. А. и др. К вопросу о патогенезе артериальной гипертензии у больных первичным гипотиреозом. Артериальная гипертензия 2012; 1

15. (18):58–61).

16. Toren AN, Kulaksizoglu S, Kulaksizoglu M et al. Serum total antioxidant status and lipid peroxidation marker malondialdehyde levels in overt and subclinical hypothyroidism. Clin. Endocrinol 2009; 70, 3:469–74.