Hypothyroidism

Introduction

• Description: Reduced or inadequate circulating levels of thyroid hormone. Women are 5–10 times more likely to suffer from hypothyroidism than men. Menstrual disturbances may be the first indication of this abnormality. Some women develop a transient (3–4 months) hypothyroid state (painless subacute thyroiditis) after giving birth.

• Prevalence: 5–10/1000 general population; 6%–10% of women older than 65 years.

• Predominant Age: Older than 40 years.

• Genetics: No genetic pattern for idiopathic type; may be associated with type II autoimmune polyglandular syndrome ( HLA-DR3 and HLA-DR4 ).

Etiology and Pathogenesis

• Causes: Idiopathic or autoimmune (most common when goiter is present)—after ablative medical or surgical therapy. The most common cause of hypothyroidism during pregnancy is chronic autoimmune (Hashimoto) thyroiditis. Postpartum thyroiditis (silent)—abnormalities of thyroid-stimulating hormone (TSH) or thyrotropin-releasing hormone (TRH) production or release.

• Risk Factors: Age, other autoimmune disease, ablative therapy, pituitary failure.

Signs and Symptoms

• Weakness, lethargy, fatigue

• Cold intolerance, hypothermia

• Menstrual disturbances (dysfunctional bleeding, amenorrhea, menorrhagia)

• Decreased memory, hearing loss

• Constipation

• Dry, coarse skin, brittle hair (hair loss is common)

• Periorbital puffiness, swelling of hands and feet

• Bradycardia, narrowed pulse pressure

• Anemia

• Cardiomegaly, pericardial effusion

Diagnostic Approach