Definition of Endemic goiter? (other source)
Endemic goiter refers to the enlargement of the thyroid gland (goiter) that is widespread within a specific geographic area or population
Stages and degrees of enlargement of thyroid gland?
WHO Classification of Goiter:
Grade 0: No goiter is palpable or visible.
Grade 1A: The goiter is palpable but not visible with the neck in a normal position.
Grade 1B: The goiter is palpable and visible with the neck in extension.
Grade 2: The goiter is clearly visible when the neck is in a normal position.
Grade 3: The goiter is very large seen from a distance
Etiology and pathophysiology of endemic goiter?
Etiology:
- The main reason for goiter formation is an iodine deficiency.
- For the normal production of hormones - the gland needs at least 200 micrograms of iodine per 24 hours.
If the consumption is:
- 100-200 gg — there is no risk;
- 50-80 ug - high risk for disease, risk for fetal anomalies;
- 25-50 ug - presence of goiter, fetal anomalies during pregnancy;
- 10-25 gg - presence of high degree goiter.
Additional factors are:
- Factors that deepen the iodine deficiency - smoking.
- Factors that suppress the hormone synthesis - insufficient level of microelements in the blood inactivates the enzymes that support the hormone synthesis.
- Medications — some lithium medications.
- Probably genetic factors — some HLA types.
Pathogenesis:
- The iodine deficiency leads to suppressed production of thyroid hormones.
- It is followed by increasing the secretion of TSH. That is the factor leading to hypertrophy of thyrocytes.
- The iodine deficiency also leads to increasing thyroid growth factors:
- epidermal growth factor
- insulin-like growth factor.
- Presence of specific antibodies — thyroid growth antibody (TGA)