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
Key diagnostic factors
- presence of risk factors
- non-specific symptoms
Other diagnostic factors
- weight gain
- menstrual irregularity
- dry or coarse skin
- change in voice
- delayed relaxation of tendon reflexes
- cold sensitivity
- coarse hair
- eyelid oedema
- 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
1st investigations to order
- serum thyroid-stimulating hormone (TSH)
Investigations to consider
- free serum T4
- antithyroid peroxidase antibodies
- fasting blood glucose
- serum cholesterol
confirmed overt primary hypothyroidism
sub-clinical hypothyroidism with TSH >10 mIU/L
Wail Malaty, MD
Adjunct Clinical Professor
Department of Family Medicine
University of North Carolina
WM declares that he has no competing interests.
Bernard Ewigman, MD
Professor of Medicine
Chair of Family Medicine
University of Chicago Medical Center
BE declares that he has no competing interests.
Salman Razvi, MD, FRCP
Queen Elizabeth Hospital
SR declares that he has no competing interests.
Lakdasa Premawardhana, MBBS, FRCP, FRCPE
Caerphilly Miners' Hospital
LP declares that he has no competing interests.
Birte Nygaard, MD, PhD
University of Copenhagen
BN declares that she has no competing interests.
Joaquin Lado, MD, PhD
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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