Mechanism
Cause
Primary Hypothyroidism
Primary Hypothyroidism
Loss of functional thyroid tissue
- Autoimmune hypothyroidism:
- Hashimoto's
- Destructive thyroiditis
- Postpartum
- Subacute
- Iatrogenic - treatment for malignancy or hyperthyroidism
- Infiltrative disease (sarcoidosis)
Functional defects in thyroid hormone synthesis and release
- Iodine deficiency (Most common worldwide)
- Drugs (Amiodarone, lithium, interferon)
- Congenital syndromes
Secondary Hypothyroidism
Secondary Hypothyroidism
Loss of functional hypothalamic or pituitary tissue
- Hypopituitarism
- Congenital lesions
Functional defects in TSH synthesis and release
- Drugs (Dopamine, glucocorticoids)
- Congenital syndromes
Peripheral Hypothyroidism
Peripheral Hypothyroidism
Resistance to thyroid hormones
- Congenital syndromes