Thyroid Dysfunction and Dysmetabolic Syndrome: The Need for Enhanced Thyrovigilance Strategies

Abstract

Thyroid dysfunction (TD) is common in metabolic disorders such as diabetes mellitus (DM), cardiovascular disease (CVD), obesity, dyslipidemia, hyperuricemia, kidney and liver dysfunctions, and polycystic ovary syndrome (PCOS). Subclinical hypothyroidism (SHypo) worsens glycemic control in patients with DM, and these patients, especially those with Type-1DM, have higher prevalence of TD. Both TD and DM increase CVD risk. Even minor alteration in thyroid hormone (TH) levels can alter cardiovascular function. While hyperthyroidism increases systolic blood pressure and leads to high-output heart failure, hypothyroidism increases diastolic blood pressure and leads to low-output heart failure. Chronic subclinical hyperthyroidism (SHyper) and SHypo both increase the risk of hypertension, coronary artery disease (CAD) events, CAD deaths, and total deaths. SHyper alters cardiac morphology and function. SHypo causes dyslipidemia and endothelial dysfunction and increases the risk for weight gain and obesity. Overweight and obese patients often have hyperleptinemia, which increases the secretion of thyroid stimulating hormone (TSH) and induces TD. Dyslipidemia associated with TD can increase serum uric acid levels. Hyperuricemia promotes inflammation and may increase the risk for dyslipidemia, atherosclerosis, and CVD. TD increases the risk for developing chronic kidney disease. In nephrotic syndrome, proteinuria is associated with urinary loss of TH leading to TD. Some correlation between TD and severity of liver disease is also seen. TD and PCOS have common risk factors and pathophysiological abnormalities. Hypothyroidism must be excluded before diagnosing PCOS. Current guidelines do not strongly recommend thyroid screening in the presence of all metabolic disorders. However, pragmatic thyrovigilance is required. Clinicians must stay alert to signs and symptoms of TD, maintain high clinical suspicion, and investigate thoroughly. Drug-induced TD should be considered when TH levels do not match clinical findings or when patients are on medications that can alter thyroid function.

Association of Subclinical Hypothyroidism with Present and Absent Anti-Thyroid Antibodies with PCOS Phenotypes and Metabolic Profile

“…The incidence of SCH in the study population (31.1%) was consistent with the results of other studies [ 13 ], while the incidence of circulating ATA (12%) and AIT (4.4%) was slightly lower [ 14 , 17 ], which may be due to the characteristics of the study population and the diagnostic criteria used. The study confirmed that TSH values > 2.5 corresponding to SCH were associated with the occurrence of significant metabolic disturbances, which was in line with the majority [ 13 , 24 , 25 , 35 ], but not all [ 36 , 37 ], of previous scientific reports, and the strongest relationship was found for hyperlipidemia and insulin resistance [ 38 ]. Interestingly, the coexistence of ATA in the subpopulation with TSH > 2.5 (AIT) did not seem to additionally affect the values of metabolic parameters and the effect of elevated TSH levels was even greater in the absence of ATA, which, however, requires further research and verification.…”

“…The coexistence of AIT with PCOS may be associated with an even greater risk of metabolic syndrome and infertility [ 22 , 23 ]. Complications pertain not only to overt hypothyroidism, but also SCH [ 24 , 25 ] and the presence of circulating anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-TG) antibodies [ 26 ]. However, not all research results are consistent in this respect.…”

A Study on the Association Between Subclinical Hypothyroidism and Polycystic Ovary Syndrome

“…Therefore, PCOS can only be diagnosed after hypothyroidism has been ruled out. The relationship between insulin resistance and hypothyroidism has been studied for decades; however, the in uence of SCH on clinical and metabolic parameters has not been su ciently investigated in the setting of PCOS [13][14][15]. Thyroid hormones are involved in the metabolism of various substances in the body and may regulate gonadal development and female reproductive endocrine function through the hypothalamic-pituitary-ovarian axis.…”

Ультраструктурні Зміни Печінки При Експериментальній Гіпергомоцистеїнемії На Тлі Гіпо- Та Гіпертиреозу

“…Гормони щитоподібної залози є регуляторами клітинного розвитку, росту та обміну речовин у ссавців [24] та контролюють ряд метаболічних процесів у клітинах, пов'язаних з анаболізмом або катаболізмом макромолекул, включаючи вуглеводи, білки, ліпіди [11]. Дисбаланс рівнів тиреоїдних гормонів в організмі повʼязаний із множинними хронічними захворюваннями, включаючи цукровий діабет, серцево-судинні захворювання та печінкові розлади [7].…”