Background: Neutrophil gelatinase-associated lipocalin (NGAL) is an inflammatory protein with gaining increasing interest for its use as marker in blood and cerebrospinal fluid (CSF) for several chronic diseases. Its biochemical properties make it an attractive marker. However, changes in blood and CSF NGAL concentrations during the diurnal rhythm in the elderly are unknown. This information is important for its optimal use as marker in studies with older people.
Methods: Serial paired plasma and CSF samples were obtained from 8 healthy elderly males over a 30-hour period. NGAL and cortisol were quantified with ELISA.
Results: No significant changes in plasma and CSF NGAL concentrations over time were found, whereas cortisol (included as internal control) concentrations displayed significant changes over time. Significant circadian patterns were found for plasma NGAL and for cortisol in both plasma and CSF. However, CSF NGAL concentrations did not follow a diurnal pattern in elderly males.
Conclusions: This study illustrates the temporal regulation of NGAL in plasma and CSF, which potentially is a useful reference for studies measuring NGAL as biomarker in older individuals.