Many persons have at least one sign or symptom that could suggest thyroid disease. Unfortunately, most of these signs and symptoms are not specific for thyroid dysfunction. Enumeration of the classic signs and symptoms of thyroid disease is the best way to emphasize these facts.


Thyrotoxicosis from excess secretion of thyroid hormone is usually caused by a diffusely hyperactive thyroid (Graves’ disease, about 75% of hyperthyroid cases) or by a hyperfunctioning thyroid nodule (Plummer’s disease, about 15% of hyperthyroid cases). A much less common cause is iodine-induced hyperthyroidism (Jod-Basedow disease), and rare causes include pituitary overproduction of TSH, ectopic production of thyroid hormone by the ovary (struma ovarii), high levels of chorionic gonadotropin (with some thyroid-stimulating activity) from trophoblastic tumors, and functioning metastic thyroid carcinoma. Thyroiditis (discussed later) may produce symptoms of thyrotoxicosis (comprising about 10% of hyperthyroid cases), but the symptoms are caused by leakage of thyroid hormones from damaged thyroid tissue rather than over secretion from intact tissue. Many hyperthyroid patients have eye signs such as exophthalmos, lid lag, or stare. Other symptoms include tachycardia; warm, moist skin; heat intolerance; nervous hyperactive appearance; loss of weight; and tremor of fingers. Less frequent symptoms are diarrhea, atrial fibrillation, and congestive heart failure. The hemoglobin level is usually normal; the white blood cell (WBC) count is normal or slightly decreased. There is sometimes an increase in the lymphocyte level. The serum alkaline phosphatase level is elevated in 42%-89% of patients. In elderly patients the clinical picture is said to be more frequently atypical, with a higher incidence of gastrointestinal symptoms, atrial fibrillation, and apathetic appearance.


Myxedema develops from thyroid hormone deficiency. Most common signs and symptoms include nonpitting edema of eyelids, face, and extremities; loss of hair in the outer third of the eyebrows; large tongue; cold, dry skin; cold intolerance; mood depression; lethargic appearance; and slow mental activity. Cardiac shadow enlargement on chest x-ray film is common, with normal or slow heart rate. Anorexia and constipation are frequent. Laboratory tests show anemia in 50% or more of myxedema patients, with a macrocytic but non- megaloblastic type in approximately 25%. The WBC count is usually normal. The cerebrospinal fluid (CSF) usually has an elevated protein level with normal cell counts, for unknown reasons. Serum creatine kinase (CK) is elevated in about 80% (range, 20%-100%) of patients; aspartate aminotransferase (AST; formerly SGOT) is elevated in about 40%-50%; and serum cholesterol is frequently over 250 mg/dl in overt cases.

Hypothyroidism in the infant is known as “cretinism.” Conditions that superficially resemble or simulate cretinism include mongolism and Hurler’s disease (because of mental defect, facial appearance, and short stature); various types of dwarfism, including achondroplasia (because of short stature and retarded bone age); and nephrosis (because of edema, high cholesterol levels, and low T4 levels). Myxedema in older children and adults may be simulated by the nephrotic syndrome, mental deficiency (because of mental slowness), simple obesity, and psychiatric depression.