Age-dependent morphologic findings of the thyroid in sudden infant death

Age (eight days to 12 months) and degree of colloid depletion or colloid content of the follicles (normal, partially depleted, depleted) were correlated on the basis of 176 thyroid investigations in cases of sudden infant death syndrome (SIDS). In the 176 SIDS cases, a resting thyroid gland with normal colloid content could only be found in 14%, whereas partially depleted follicles were found in 35% and depleted follicles in 51%. 60% of all cases showed a large degree of epithelial desquamation up to collapse of all follicles. A marked capillary hyperemia was found in 48%. 80% of the cases showed a normal colloid content in the first month of life, and colloidfree follicles should not be detected in any case. An increased incidence of thyroid activation was obtained in the total number of cases only from the second month of life. The histomorphological appearance of the thyroid gland thus corresponds to that of healthy infants only in the first month of life. The question as to why there is an evidently raised thyroid activity in the subsequent months of life in SIDS cases is discussed.