Subclinical Hypothyroidism and the Risk of Coronary Heart Disease and Mortality

Abstract

for the Thyroid Studies Collaboration C ONTROVERSY PERSISTS ON THEindications for screening and threshold levels of thyroidstimulating hormone (TSH) for treatment of subclinical hypothyroidism, 1-3 defined as elevated serum TSH levels with normal thyroxine (T 4 ) concentrations. Because subclinical hypothyroidism has been associated with hypercholesterolemia 4 and atherosclerosis, 5 screening and treatment have been advocated to prevent cardiovascular disease. 3 However, data on the associations with coronary heart disease (CHD) events and mortality are conflicting among several large prospective cohorts. [6][7][8][9] Three recent study-level metaanalyses 10-12 found modestly increased risks for CHD and mortality, but with heterogeneity among individual studies that used different TSH cutoffs, dif-See also Patient Page. CME available online at www.jamaarchivescme.com and questions on p 1392.

Natural history of mild subclinical hypothyroidism in a middle-aged and elderly Chinese population: a prospective study

“…Although these results are less comparable because of different characteristics of participants in the different studies, we found a regression rate higher than most previous studies in our study, which was the only one to enroll only patients with mild SCH from both sexes. Based on previous studies and expert reviews, we used 7.0 mIU/L of TSH as cut-off points [1,13] and found that higher TSH concentrations significantly impaired the likelihood of TSH normalization in our logistic regression analysis, similar to previous studies [6,8,10]. Accordingly, the generally lower TSH levels among our cases compared with previous studies may be one of the reasons that TSH normalization occurred in a high proportion of our patients.…”

“…SCH was defined as a combination of elevated TSH and normal FT4, and classified into mild or severe when TSH ≤10 mIU/L or >10 mIU/L, respectively [4]. Positivity for TPOAb was considered when the serum mortality in those with higher TSH levels [13]. Other possible adverse consequences include depression, Alzheimer disease, the worsening of renal function in patients with chronic kidney diseases (CKD), symptomatic OH and disordered lipid metabolism, particularly elevation of total cholesterol (TC) [2,4].…”

Risk assessment of the subclinical hypothyroidism in non-alcoholic fatty liver disease patients with different levels of cardiovascular risk

“…A systematic review of 13 heterogeneous studies has demonstrated the effect of substitution therapy with Levothyroxine at SH on reducing the concentrations of LDL cholesterol and total cholesterol [7]. Similar results have been demonstrated in other RCTs [8].…”

“…On the background of substitution therapy with Levothyroxine in patients with SH a decrease of carotid arteries intima-media thickness [6], an improvement of endothelial function [5], improvement of cardiac function [4] were observed. Such therapy may reduce the risk of coronary heart disease in relatively young patients with SH, but not in people aged over 70 years [8]. Adequate RCTs devoted to the study of cardiovascular events in the renew of euthyroidism is still few.…”

Prevalence of subclinical hypothyroidism in adults visiting primary health-care setting in Riyadh

“…Although elevated TSH in older adults was found to be associated with decreased mortality [3], there is a great body of literature that suggests many negative effects of elevated TSH on health. It was found to be associated with cardiac dysfunction [4], higher low-density lipoprotein cholesterol [5]. Some studies even found association with depression and cognitive dysfunction [6] although the evidence for this is not conclusive [7].…”