Hypothyroidism Pubmed

[Ara Kistner]

Thesite is secure.

The ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Hypothyroidism is the common clinical condition of thyroid hormone deficiency and, if left untreated, can lead to serious adverse health effects on multiple organ systems, with the cardiovascular system as the most robustly studied target. Overt primary hypothyroidism is defined as elevated thyroid-stimulating hormone (TSH) concentration in combination with free thyroxine (fT4) concentration below the reference range. Subclinical hypothyroidism, commonly considered an early sign of thyroid failure, is defined by elevated TSH concentrations but fT4 concentrations within the reference range. Hypothyroidism is classified as primary, central or peripheral based on pathology in the thyroid, the pituitary or hypothalamus, or peripheral tissue, respectively. Acquired primary hypothyroidism is the most prevalent form and can be caused by severe iodine deficiency but is more frequently caused by chronic autoimmune thyroiditis in iodine-replete areas. The onset of hypothyroidism is insidious in most cases and symptoms may present relatively late in the disease process. There is a large variation in clinical presentation and the presence of hypothyroid symptoms, especially in pregnancy and in children. Levothyroxine (LT4) is the mainstay of treatment and is one of the most commonly prescribed drugs worldwide. After normalization of TSH and fT4 concentrations, a considerable proportion of patients treated with LT4 continue to have persistent complaints, compromising quality of life. Further research is needed regarding the appropriateness of currently applied reference ranges and treatment thresholds, particularly in pregnancy, and the potential benefit of LT4/liothyronine combination therapy for thyroid-related symptom relief, patient satisfaction and long-term adverse effects.

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.

Clinical hypothyroidism affects one in 300 people in the United States, with a higher prevalence among female and older patients. Symptoms range from minimal to life-threatening (myxedema coma); more common symptoms include cold intolerance, fatigue, weight gain, dry skin, constipation, and voice changes. The signs and symptoms that suggest thyroid dysfunction are nonspecific and nondiagnostic, especially early in disease presentation; therefore, a diagnosis is based on blood levels of thyroid-stimulating hormone and free thyroxine. There is no evidence that population screening is beneficial. Symptom relief and normalized thyroid-stimulating hormone levels are achieved with levothyroxine replacement therapy, started at 1.5 to 1.8 mcg per kg per day. Adding triiodothyronine is not recommended, even in patients with persistent symptoms and normal levels of thyroid-stimulating hormone. Patients older than 60 years or with known or suspected ischemic heart disease should start at a lower dosage of levothyroxine (12.5 to 50 mcg per day). Women with hypothyroidism who become pregnant should increase their weekly dosage by 30% up to nine doses per week (i.e., take one extra dose twice per week), followed by monthly evaluation and management. Patients with persistent symptoms after adequate levothyroxine dosing should be reassessed for other causes or the need for referral. Early recognition of myxedema coma and appropriate treatment is essential. Most patients with subclinical hypothyroidism do not benefit from treatment unless the thyroid-stimulating hormone level is greater than 10 mIU per L or the thyroid peroxidase antibody is elevated.

Hypothyroidism results from low levels of thyroid hormone with varied etiology and manifestations. Hypothyroidism is primarily categorized as primary and secondary (ie, central) hypothyroidism. In primary hypothyroidism, the thyroid gland cannot produce adequate amounts of thyroid hormone. The less commonly seen secondary or central hypothyroidism occurs when the thyroid gland functions normally; however, hypothyroidism results from the abnormal pituitary gland or hypothalamus function. Autoimmune thyroiditis and iodine deficiency are the most common causes of the disease. Central hypothyroidism is rare.

The drug of choice for the treatment of hypothyroidism of any etiology is thyroid hormone replacement. Untreated hypothyroidism increases morbidity and mortality. This activity for healthcare professionals aims to enhance learners' competence in selecting appropriate diagnostic tests, managing hypothyroidism, and fostering effective interprofessional teamwork to improve outcomes.

Objectives:Differentiate between primary and secondary hypothyroidism to guide appropriate treatment.Select appropriate diagnostic tests and interpret results for comprehensive patient care. Implement evidence-based treatment strategies, including medication management and lifestyle interventions. Determine appropriate strategies to optimize care coordination among interprofessional team members to improve outcomes for patients affected by hypothyroidism.Access free multiple choice questions on this topic.

Hypothyroidism results from low levels of thyroid hormone with varied etiology and manifestations. Hypothyroidism is primarily categorized as primary and secondary (ie, central) hypothyroidism. In primary hypothyroidism, the thyroid gland cannot produce adequate thyroid hormone. The less commonly seen secondary or central hypothyroidism occurs when the thyroid gland functions normally; however, hypothyroidism results from the abnormal pituitary gland or hypothalamus function. Untreated hypothyroidism increases morbidity and mortality. In the United States, autoimmune thyroid disease (ie, Hashimoto thyroiditis) is the most common cause of hypothyroidism, but globally, lack of iodine in the diet is the most common cause.[1]

The presentation can vary from an asymptomatic patient in whom hypothyroidism is only recognized on routine blood work to myxedema coma, which is an extreme presentation of this condition. Classic clinical features, including cold intolerance, puffiness, decreased sweating, and skin changes, may not always be present.[2] A serum TSH level is typically used to assess for primary hypothyroidism in most patients initially.[2] Characteristic laboratory findings of hypothyroidism include elevated TSH levels and low free T4 levels. Today, the diagnosis of hypothyroidism is easily made by the use of simple blood tests and can be treated with exogenous thyroid hormone.[3]

Hypothyroidism is primarily categorized as primary and secondary (ie, central) hypothyroidism. In primary hypothyroidism, the thyroid gland cannot produce adequate amounts of thyroid hormone. The less commonly seen secondary or central hypothyroidism occurs when the thyroid gland functions normally; however, hypothyroidism results from the abnormal pituitary gland or hypothalamus function.

The most prevalent etiology of primary hypothyroidism is an iodine deficiency in iodine-deficient geographic areas worldwide. Autoimmune thyroid diseases are the leading causes of hypothyroidism in the iodine-sufficient regions. Hashimoto thyroiditis is the most commonly seen etiology in the US and has a strong association with lymphoma. Hypothyroid etiology can be influenced locally by iodine fortification and the emergence of new iodine-deficient areas.[1]

Other conditions may also lead to primary hypothyroidism. Postpartum thyroiditis affects nearly 10% of women and often presents 8 to 20 weeks after the delivery of the infant. Only a few women require treatment with thyroid hormone. However, some women are at high risk for permanent hypothyroidism or recurrent postpartum thyroiditis in future pregnancies.[4] The use of radioactive iodine to manage Graves disease usually results in permanent hypothyroidism in about 80% to 90% of the patients within 8 to 20 weeks after treatment.[5][6] A relatively uncommon cause of primary hypothyroidism is subacute granulomatous thyroiditis, also known as de Quervain disease. Subacute granulomatous thyroiditis usually occurs in middle-aged women and is typically self-limited. Hypothyroidism can also be a part of the autoimmune polyendocrinopathy type-1 condition that results from a mutation in the AIRE gene. This condition is a constellation of Addison disease, hypoparathyroidism, and mucocutaneous candidiasis. Polyendocrinopathy type-2 includes hypothyroidism, Addison disease, and type 1 diabetes mellitus.[7][8] Other common causes of hypothyroidism include:

3a8082e126