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Updated: Jun 21, 2026

Human Circadian Phenotyping and Diurnal Performance Testing in the Real World
Published on: April 7, 2020
Pineal volume and circadian melatonin profile in healthy volunteers: an interdisciplinary approach
Ingo Nölte1, Ann-Theres Lütkhoff, Boris A Stuck
1Department of Neuroradiology, Medical Faculty Mannheim of the University of Heidelberg, Germany. Ingo.noelte@rad.ma.uni-heidelberg.de
Purpose:
To correlate pineal parenchyma volume (PP) to circadian melatonin profiles and to determine the 24-hour melatonin per volume of pineal tissue (MLPV). Furthermore, we compared melatonin profiles of cystic and solid glands.
Methods:
In 15 healthy male subjects (20-27 years) the PP was determined using high-resolution magnetic resonance imaging (trueFISP, isotropic voxel: 0.8 mm(3)). Melatonin plasma concentrations (MC) were determined every 2 hours for 24 hours.
Results:
Mean PP was 125 +/- 54 mm(3). PP correlated linearly to maximum MC and to 24-hour melatonin (r = 0.61 and r = 0.64, P < 0.05) but not to minimum MC. The 24-hour melatonin was 653 +/- 242.6 pg/mL, MLPV was 5.8 +/- 2.3 pg/mL*ml(-1). Nine pineal glands were solid and six were cystic. PP of solid glands showed higher linear correlations to maximum melatonin, to 24-hour melatonin, and to the slope of the melatonin increase of the curve (P < 0.05).
Conclusion:
PP correlates linearly to melatonin plasma concentrations in humans. MLPV displays similar interindividual differences as 24-hour melatonin. PP of solid glands show better correlation to melatonin profiles than cystic.
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