goiter

Goiter (rarely thyromegaly) refers to enlargement of the thyroid gland. It can occur from multiple conditions. Clearly the absence of thyroid enlargement does not preclude significant thyroid pathology.

The definition of a goiter depends on age and sex; below are the upper limits of normal for thyroid gland volume :

  • adult males: 25 mL
  • adult females: 18 mL
  • 13-14 years: 8-10 mL
  • 3-4 years: 3 mL
  • neonate: 0.8-1.5 mL

Epidemiology

The prevalence of goiter varies widely depending on the level of iodine deficiency. In severely iodine-deficient areas the prevalence may be as a high as 80%. Goiter is more common in women (M:F = 1:4) and incidence declines with age .

Pathology

The thyroid gland may become so enlarged that it becomes a substernal (retrosternal) goiter.

Etiology

The causes of goiter are diverse :

Radiographic features

Ultrasound/CT
  • each lobe normally measures :
    • length: 4-7 cm
    • depth: <2 cm
    • isthmus ≤0.5 cm deep

Thyroid volume can be estimated by measuring each lobe and applying the following correction factor for an ellipsoid formula :

  • height (cm) x width (cm) x depth (cm) x 0.529*

* various correction factors between 0.494-0.554 have also been proposed

  • volume (excluding isthmus, unless its thickness is >3 mm) 
    • 10-15 mL for females
    • 12-18 mL for males

History and etymology

Goiter derives from the old French "goitron" meaning gullet. Goitron comes from the Latin "guttur" meaning throat.

Differential diagnosis

See main article: midline neck mass

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