Goiter

Excerpt

Goiter means enlargement of the thyroid gland and is a general term that conveys the information that the volume of the thyroid gland is larger than normal. The presence of goiter can be determined by inspection, palpation, or by an imaging study.

Normal thyroid gland measures 4 to 4.8 cm in sagittal, 1 to 1.8 cm in transverse, and 0.8 to 1.6 cm in anteroposterior dimensions. This corresponds to a volume of 7 to 10 mL on ultrasonography calculations and 10-20 grams in weight. Thyroid size increases with age and body size. It is larger in males as opposed to females. The size decreases with higher iodine intake.

The thyroid gland can enlarge due to a variety of physiological or pathological stimuli. Goiter during adolescence and pregnancy are two causes of a physiological goiter. Goiter can be associated with euthyroidism, hypothyroidism, or hyperthyroidism. It can be diffuse, nodular, or multinodular. The thyroid gland usually grows anteriorly in the neck, because the enlarging thyroid is not constrained by the weak anterior cervical muscles, subcutaneous tissue, or the skin. The term goiter is usually used to denote cervical goiter. If the thyroid gland enlarges inferiorly and passes through the thoracic inlet, then it is called a substernal or retrosternal goiter.