Patients with primary hypothyroidism usually present with non-specific symptoms of weakness, lethargy, depression, and mild weight gain.
Commonly, disease is sub-clinical.
Physical examination may show dry skin, thick tongue, eyelid oedema, and bradycardia.
Elevated thyroid-stimulating hormone and low free thyroxine confirms the diagnosis.
Treatment is with levothyroxine; starting dose depends on age and presence of co-existing cardiac disease.
Over-treatment is uncommon but can lead to iatrogenic hyperthyroidism.
Hypothyroidism is a clinical state resulting from underproduction of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). Most cases are due to primary hypothyroidism, a failure of the thyroid gland to produce thyroid hormones. Primary hypothyroidism is defined as thyroid-stimulating hormone (TSH) concentrations above the reference range and free thyroxine concentrations below the reference range. Secondary hypothyroidism is due to underproduction of TSH by the pituitary gland. Sub-clinical hypothyroidism is a state of usually asymptomatic, mild thyroid failure, with normal levels of T4 and T3, and minimal elevation of TSH. Myxoedema coma is a rare severe form of hypothyroidism with multi-organ failure.
History and exam
- iodine deficiency
- female sex
- middle age
- family history of autoimmune thyroiditis
- autoimmune disorders
- treatment for thyroid disease
- post-partum thyroiditis
- Turner's and Down's syndromes
- type 1 diabetes
- radiotherapy to head and neck
- infiltrative disease
- iodine excess
- amiodarone use
- lithium use
Adjunct Clinical Professor
Department of Family Medicine
University of North Carolina
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Professor of Medicine
Chair of Family Medicine
University of Chicago Medical Center
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Queen Elizabeth Hospital
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Caerphilly Miners' Hospital
LP declares that he has no competing interests.
University of Copenhagen
BN declares that she has no competing interests.
Professor of Internal Medicine
Endocrinology Division Chief
Texas Tech University Health Sciences Center - School of Medicine
JL declares that he has no competing interests.
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