Hypothyroidism is a disorder of the endocrine system in which the thyroid gland does not produce enough hormone. Hypothyroidism is a condition where the body lacks sufficient thyroid hormone. Since the main purpose of thyroid hormone is to "run the body’s metabolism," people with this condition experience symptoms related to a slowed metabolism.
Causes of Hypothyroidism
- Primary Hypothyroidism: The chief cause is an autoimmune disorder in which the body’s immune system attacks the thyroid gland, leading to its destruction. Another common cause is iodine deficiency.
- Secondary Hypothyroidism: This occurs when the hypothalamus produces insufficient thyrotropin-releasing hormone (TRH) or when the pituitary gland produces insufficient thyroid-stimulating hormone (TSH).
Signs and Symptoms
The symptoms and signs of primary hypothyroidism are often subtle and develop gradually. Various organ systems can be affected.
- Metabolic Symptoms: Cold intolerance, modest weight gain (due to fluid retention and decreased metabolism).
- Neurologic Symptoms: Forgetfulness, numbness of the hands and feet.
- Psychiatric Symptoms: Personality changes, depression, dull facial expression, dementia, or psychosis.
- Skin Symptoms: Facial puffiness, myxedema, sparse and coarse dry hair, coarse and scaly thick skin, carotenemia (particularly noticeable on palms and soles), macroglossia (enlarged tongue due to proteinaceous ground substance deposition).
- Ocular Symptoms: Puffy swelling around the eyes.
- Gastrointestinal Symptoms: Constipation.
- Gynecologic Symptoms: Irregular menstrual flow, increase or decrease in menstrual flow.
- Cardiovascular Symptoms: Slow heart rate (bradycardia due to reduced thyroid hormone and adrenergic stimulation), enlarged heart on examination or imaging.
- Other Symptoms: Pleural or abdominal effusions (usually slow-developing), hoarse voice, and slow speech.
