Hypothyroidism

Abstract

Hypothyroidism is a common condition of thyroid hormone deficiency, which is readily diagnosed and managed but potentially fatal in severe cases if untreated. The definition of hypothyroidism is based on statistical reference ranges of the relevant biochemical parameters and is increasingly a matter of debate. Clinical manifestations of hypothyroidism range from life threatening to no signs or symptoms. The most common symptoms in adults are fatigue, lethargy, cold intolerance, weight gain, constipation, change in voice, and dry skin, but clinical presentation can differ with age and sex, among other factors. The standard treatment is thyroid hormone replacement therapy with levothyroxine. However, a substantial proportion of patients who reach biochemical treatment targets have persistent complaints. In this Seminar, we discuss the epidemiology, causes, and symptoms of hypothyroidism; summarise evidence on diagnosis, long-term risk, treatment, and management; and highlight future directions for research.

Antibodies Regulate Dual-Function Enzyme IYD to Induce Functional Synergy between Metabolism and Thermogenesis

“…T4 is the main circulating hormone in the blood. Low T4 levels indicate hypothyroidism, which can affect the heart and circulatory system in various ways [ 11 , 15 , 16 , 17 , 19 , 20 ]. Despite our finding that H3 Ab-treated mice had significantly decreased free thyroxine (T4) levels, resulting from less available iodine, another feature of hypothyroidism, we cannot rule out the involvement of off-target effects of H3 Ab that may have indirectly decreased iodine without blocking the function of IYD.…”

Social Determinants of Health on Cardiovascular Disease Prevention in Special Populations: An Overview

“…Overt hypothyroidism is characterized by thyroid-stimulating hormone (TSH) levels above the reference range and free thyroxine (T4) below the reference range. Subclinical hypothyroidism (SH) is characterized by TSH levels above the reference range with normal free T4 levels [10,11,12,13]. Thyroid hormones are fundamental for the normal functioning of the cardiovascular system.…”

“…In addition, SH with TSH levels greater than 10 mlU/L increases the risk of ischemic heart disease and mortality due to CVD [11,14,15]. According to the National Health and Nutrition Examination Survey (NHANES), the prevalence of hypothyroidism in the US is 4.6% [10,11,13]. Other studies conducted in the US reported a prevalence of overt hypothyroidism and SH of 0.4% and 10%, respectively [10,11,12,13].…”

“…According to the National Health and Nutrition Examination Survey (NHANES), the prevalence of hypothyroidism in the US is 4.6% [10,11,13]. Other studies conducted in the US reported a prevalence of overt hypothyroidism and SH of 0.4% and 10%, respectively [10,11,12,13]. Multiple studies have associated some SDoH with hypothyroidism, including age, sex, race/ethnicity, socioeconomic status, and education.…”

“…Furthermore, poor access to health care and low-educated individuals were correlated with low adherence to treatment and iodine supplementation programs [15]. There is adequate data to support that treatment of hypothyroidism can reverse some cardiovascular effects [10,11,14,16]. In patients with SH and TSH levels >10 mIU/L, levothyroxine treatment reduced cardiovascular morbidity and mortality [10,11,16].…”