How kidney clock works: circadian pattern of eGFR based on a population data group

Area of Science:

• Nephrology
• Chronobiology
• Public Health

Background:

• Circadian regulation of renal function is increasingly recognized.
• Intradaily variations in estimated glomerular filtration rate (eGFR) have been observed at the individual level.

Purpose of the Study:

• To investigate the existence of a circadian eGFR pattern at the population level.
• To compare population-level eGFR patterns with previously described individual patterns.

Main Methods:

• Analysis of 446,441 eGFR records from two Spanish hospitals (2015-2019).
• Selection of eGFR values between 60-140 mL/min/1.73 m² for patients aged 18-85.
• Application of four nested mixed linear and sinusoidal regression models to determine intradaily eGFR patterns.

Main Results:

• All models demonstrated an intradaily eGFR pattern.
• Inclusion of age improved model performance, with the acrophase occurring at 7:46 h.
• Population eGFR distributions adjusted to a circadian rhythm, similar to individual rhythms and consistent across years and hospitals.

Conclusions:

• A population circadian rhythm in eGFR exists and is comparable to individual rhythms.
• The concept of