Colloid nodular goiter is the enlargement of an otherwise normal thyroid gland.

See also: Goiter

Colloid nodular goiters are also known as endemic goiters. They are usually caused by inadequate iodine in diet.

Colloid nodular goiters tend to occur in certain geographical areas with iodine-depleted soil, usually areas away from the sea coast. An area is defined as endemic for goiter if more than 10 % of children aged 6 to 12 have goiters.

Certain things in the environment may also cause thyroid enlargement.

Small- to moderate-sized goiters are relatively common in the United States. The Great Lakes, Midwest, and Intermountain regions were once known as the "goiter belt." The routine use of iodized table salt now helps prevent this deficiency.

Risk factors for colloid nodular goiters include being female, being older than 40, not getting enough iodine in your diet, living in an endemic area, and having a family history of goiters.

• Thyroid swelling -- may be one small nodule to a very large mass
• Breathing difficulties (rare)
• Swallowing difficulties (rare)
• Enlarged neck veins
• Dizziness when the arms are raised above the head (large goiter)

• Thyroid scan
• Thyroid ultrasound
• Blood tests to monitor thyroid function including thyroid stimulating hormone (high if underactive, low if overactive)
• Radioactive iodine uptake (normal or increased)
• Urinary excretion of iodine (low)