Hashimoto's Thyroiditis
Hashimoto's thyroiditis is the most common cause of hypothyroidism in the United States. The immune system produces antibodies that gradually damage thyroid cells, impairing hormone production over months to years. Thyroid function can fluctuate -- patients may experience swings between low and transiently elevated thyroid hormone levels before settling into hypothyroidism.
Symptoms
Fatigue, cold intolerance, weight changes, hair thinning, cognitive slowing, mood changes, palpitations during the inflammatory phase, and a mildly enlarged, non-tender thyroid. Many patients feel unwell even when TSH is in the normal range.
Causes and risk
Autoimmune predisposition combined with environmental triggers (iodine excess, selenium deficiency, viral infections, stress, pregnancy) drives the immune response. It is eight to ten times more common in women, peaks in the 30 -- 50 age range, and clusters with other autoimmune conditions (celiac disease, type 1 diabetes, rheumatoid arthritis).
How it is evaluated
Anti-TPO antibodies are elevated in 90 -- 95% of cases; anti-thyroglobulin antibodies in 60 -- 80%. TSH and free T4 establish current thyroid function status. Ultrasound shows heterogeneous, hypoechoic texture with reduced vascularity.
Treatment
If TSH is elevated, levothyroxine is initiated. Selenium supplementation (200 mcg/day) has evidence for reducing antibody levels and may improve quality of life. Gluten elimination is reasonable in confirmed celiac disease. We monitor TSH and symptoms every six to twelve months, adjusting treatment as the disease evolves.