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Lack of pineal growth during childhood
F Schmidt1, B Penka, M Trauner
1Department of Radiology, University of Graz, Graz Institute of Statistics, Vienna, Austria.
Insights
Pineal gland growth appears to stop after infancy, unlike the pituitary gland which continues to develop throughout childhood. This lack of pineal growth may explain stable melatonin excretion despite falling serum melatonin levels in children.
Area of Science:
- Pediatric endocrinology
- Neuroimaging
- Chronobiology
Background:
- Serum melatonin concentrations decrease significantly during childhood, yet 24-hour melatonin excretion remains stable.
- A proposed mechanism for this phenomenon is the cessation of pineal gland growth after infancy.
Purpose of the Study:
- To investigate the growth patterns of the pineal and pituitary glands in children.
- To test the hypothesis that pineal gland growth arrests after infancy.
Main Methods:
- Review of 332 normal magnetic resonance imaging brain studies of children aged 1 day to 15 years.
- Estimation of pineal and pituitary gland sizes.
- Analysis of pineal cyst prevalence and distribution across age groups.
Main Results:
- The pineal gland showed no significant size difference with age after 1 year.
- Pituitary gland size increased approximately 100% from age 1 to 15 years.
- The pituitary gland was slightly larger in females than in males.
Conclusions:
- The findings support the hypothesis of a growth arrest in the pineal gland after infancy.
- This contrasts with the continuous development observed in the pituitary gland during the same period.
- The lack of pineal growth may be a key factor in the observed melatonin secretion patterns in children.
Abstract:
During childhood, serum melatonin concentrations drop by approximately 80%, but the 24-h melatonin excretion is stable. Arrest of pineal growth after the end of infancy has been proposed as one possible mechanism underlying that phenomenon. To test this hypothesis, we reviewed 332 magnetic resonance imaging brain studies, classified as normal, of endocrine-normal children, aged 1 day to 15 yr, and estimated the pineal and pituitary sizes. The pineal was identified in 277 of 332 magnetic resonance imaging studies (83%). The average size (mean +/- SEM) of the pineal gland (transaxial diameter, 5.6 +/- 2.1; midsagittal diameter, 5.0 +/- 2.4; planimetric area, 28.5 +/- 17.8) did not differ with age. A total of 74 of 277 pineals with cysts (26.7%) were found. The occurrence of pineal cysts was equally distributed among the different age groups (chi 2 = 11.6; df = 14; P = 0.7). Ten pineals showed more than 1 cyst (3.6%). The pituitary was identified in 325 of 332 brain images (97.9%). The average pituitary size increased by some 100% from 1 to 15 yr of age [transaxial diameter: F = 2.2; P = 0.005 (by two-way analysis of variance); midsagittal diameter: F = 3.7; P = 0.0001; planimetric area: F = 7.1; P = 0.0001]. The pituitary was slightly larger in females than in males [midsagittal diameter: F = 8.8; P = 0.003 (by two-way analysis of variance); planimetric area: F = 7.9, P = 0.005]. The data presented indicate a lack of a discernible pineal growth after age 1 yr, which contrasts with pituitary development in the same individuals. The data are in agreement with a hypothesis suggesting a growth arrest of the pineal after infancy.