Hypothyroidism
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Basics
Description
- Decreased level of thyroid hormone leads to a variety of clinical manifestations
- More common in women and the elderly
- Myxedema coma is a rare, extreme form of hypothyroidism characterized by altered mental status and defective thermoregulation triggered by a precipitating event in a patient with hypothyroidism
Etiology
- Primary:
- Idiopathic
- Congenital
- Autoimmune:
- Thyroiditis
- Hashimoto disease
- Iatrogenic:
- Postsurgical
- External radiation
- Radioiodine therapy
- Drugs:
- Iodides, lithium, amiodarone, sunitinib, bexarotene, interferons, narcotics, sedatives
- Phenytoin and carbamazepine increase clearance of T4 in patients with hypothyroidism taking T4
- Neoplasm: Primary (carcinoma) or secondary (infiltration)
- Infection: Viral (rarely aerobic or anaerobic bacteria)
- Iodine deficiency (most common cause worldwide)
- Central (very rare):
- Pituitary or hypothalamic disorder induced by drugs or severe illness
- May have other associated hormone deficiencies
- Myxedema coma:
- Life-threatening decompensation of a patient with hypothyroidism due to a stress, often during winter months
- Stressors include:
- Infection
- Hypothermia
- Intoxication
- Drugs (e.g., opioids)
- Cerebrovascular accident
- Heart failure
- Trauma
Pregnancy Considerations
- Hypothyroidism has been associated with preterm delivery, placental abruption, preeclampsia, low birth weight, and increased rate of Caesarean section
- Hypothyroid women require increased exogenous thyroid hormone replacement during pregnancy above baseline
- Postpartum thyroiditis occurs in up to 10% of women:
- Usually 3–6 mo postpartum
- Typically resolves without treatment
-- To view the remaining sections of this topic, please log in or purchase a subscription --
Basics
Description
- Decreased level of thyroid hormone leads to a variety of clinical manifestations
- More common in women and the elderly
- Myxedema coma is a rare, extreme form of hypothyroidism characterized by altered mental status and defective thermoregulation triggered by a precipitating event in a patient with hypothyroidism
Etiology
- Primary:
- Idiopathic
- Congenital
- Autoimmune:
- Thyroiditis
- Hashimoto disease
- Iatrogenic:
- Postsurgical
- External radiation
- Radioiodine therapy
- Drugs:
- Iodides, lithium, amiodarone, sunitinib, bexarotene, interferons, narcotics, sedatives
- Phenytoin and carbamazepine increase clearance of T4 in patients with hypothyroidism taking T4
- Neoplasm: Primary (carcinoma) or secondary (infiltration)
- Infection: Viral (rarely aerobic or anaerobic bacteria)
- Iodine deficiency (most common cause worldwide)
- Central (very rare):
- Pituitary or hypothalamic disorder induced by drugs or severe illness
- May have other associated hormone deficiencies
- Myxedema coma:
- Life-threatening decompensation of a patient with hypothyroidism due to a stress, often during winter months
- Stressors include:
- Infection
- Hypothermia
- Intoxication
- Drugs (e.g., opioids)
- Cerebrovascular accident
- Heart failure
- Trauma
Pregnancy Considerations
- Hypothyroidism has been associated with preterm delivery, placental abruption, preeclampsia, low birth weight, and increased rate of Caesarean section
- Hypothyroid women require increased exogenous thyroid hormone replacement during pregnancy above baseline
- Postpartum thyroiditis occurs in up to 10% of women:
- Usually 3–6 mo postpartum
- Typically resolves without treatment
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