Hypothyroidism in Context: Where We’ve Been and Where We’re Going

Abstract

Hypothyroidism affects up to 5% of the general population, with a further estimated 5% being undiagnosed. Over 99% of affected patients suffer from primary hypothyroidism. Worldwide, environmental iodine deficiency is the most common cause of all thyroid disorders, including hypothyroidism, but in areas of iodine sufficiency, Hashimoto’s disease (chronic autoimmune thyroiditis) is the most common cause of thyroid failure. Hypothyroidism is diagnosed biochemically, being overt primary hypothyroidism defined as serum thyroid-stimulating hormone (TSH) concentrations above and thyroxine concentrations below the normal reference range. Symptoms of hypothyroidism are non-specific and include mild to moderate weight gain, fatigue, poor concentration, depression, and menstrual irregularities, while the consequences of untreated or under-treated hypothyroidism include cardiovascular disease and increased mortality. Levothyroxine has long been the main tool for treating hypothyroidism and is one of the world’s most widely prescribed medicines. In adults with overt hypothyroidism, levothyroxine is usually prescribed at a starting dose of 1.6 µg/kg/day, which is then titrated to achieve optimal TSH levels (0.4–4.0 mIU/L), according to the therapeutic target. We here summarise the history of levothyroxine and discuss future issues regarding the optimal treatment of hypothyroidism. Because nearly one-third of patients with treated hypothyroidism still exhibit symptoms, it is important that levothyroxine is used more appropriately to achieve maximum benefit for patients. In order to ensure this, further research should include more accurate assessments of the true prevalence of hypothyroidism in the community, optimisation of the levothyroxine substitution dose, proper duration of treatment, and identification of patients who may benefit from combination therapy with levothyroxine plus levotriiodothyronine.Funding: Merck.Plain Language Summary: Plain language summary available for this article.

Hypothyroidism-Induced Nonalcoholic Fatty Liver Disease (HIN): Mechanisms and Emerging Therapeutic Options

“…Hypothyroidism is characterized by high plasma thyroid-stimulating hormone (TSH) in concurrence with either low plasma TH levels and a free thyroxine (fT4) that is within the reference range without obvious clinical symptoms (subclinical hypothyroidism) or with low fT4 accompanied by obvious clinical symptoms (overt hypothyroidism). Related to the cause, hypothyroidism is primarily due to thyroid dysfunction and secondary to the flawed hypothalamic–pituitary axis or to different disorders [ 27 , 28 ]. Current guidelines recommend that for subclinical hypothyroidism diagnosis, the cut-off level of TSH used should be between 4.0 and 4.5 mIU/l.…”

Minerals: An Untapped Remedy for Autoimmune Hypothyroidism?

“…The most prevalent disease entities resulting from autoimmune insult are Hashimoto's thyroiditis (HT) and Grave's disease (GD) [1]. HT manifests commonly as hypofunctioning of the gland and often reflects clinically with hypothyroidism features such as fatigue, constipation, irregular menses, cold intolerance, and weight gain, to name a few [1,2]. Meanwhile, GD manifests clinically with hyperthyroidism features such as palpitations, anxiety, menstrual dysfunction, heat intolerance, and weight loss [1,2].…”

“…HT is the most common cause of hypothyroidism in the developed world and areas with sufficient iodine repletion. In contrast, iodine deficiency still is the number one cause for hypothyroidism in regions where nutritional iodine deficiency exists [2]. HT is more commonly associated with anti-thyroid peroxidase antibody (TPO-Ab) and anti-thyroglobulin (TG) antibodies in serum resulting in lymphocyte infiltration, fibrosis in later stages.…”

“…We aim to determine if there is compelling evidence in the literature to incorporate screening for mineral deficiencies and supplement the needed minerals as part of comprehensive HT management. Figure 1 represents the various factors involved in the development of autoimmune thyroiditis [ 2 , 5 - 7 ].…”

Incidence and predictors of thyroid gland invasion by laryngeal carcinoma: a 7-year experience review

“…If untreated, it can lead to delayed wound healing and recovery, increased risk of fistula formation and major cardiovascular complications that can lead to mortality [11,12]. Treatment requires lifelong thyroid stimulation hormone (TSH) monitoring and thyroid hormone replacement therapy [13][14][15]. On the other hand, postoperative hypocalcemia, can be very agonizing to both the patient and the surgeon with the inconvenience of replacement therapy which includes multiple pills and doses throughout the day with the associated symptoms and morbidity that can be temporary or permanent [8,16].…”