Circadian variation of platelet function measured with the PFA-100
Related Experiment Video
Updated: Jun 19, 2026
Dynamic Multiparameter Platelet Function Assessment Using a Capacitive Biosensor
Published on: May 2, 2025
1Institute of Experimental and Clinical Pharmacology and Toxicology, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.
Insights
This study reveals a daily rhythm in human platelet function, with impaired function at night. The Platelet Function Analyzer-100 (PFA-100) effectively measures these circadian changes in whole blood under high shear stress.
Area of Science:
- Physiology
- Pathophysiology
- Chronobiology
Background:
- Circadian rhythms significantly influence human physiology and disease processes.
- Previous studies indicated circadian variations in platelet function, but were limited by methodology (optical aggregometry, low shear stress).
Purpose of the Study:
- To investigate the impact of circadian rhythms on platelet function in whole blood under high shear rates.
- To evaluate the suitability of the Platelet Function Analyzer-100 (PFA-100) for assessing circadian alterations in platelet activity.
Main Methods:
- Healthy volunteers' platelet function was assessed using the PFA-100 with collagen/epinephrine and collagen/ADP cartridges.
- Measurements were taken at various intervals throughout a 24-hour period.
- Concentrations of fibrinogen and factor VIII activity were also determined.
Main Results:
- Platelet function, indicated by closure time on the PFA-100, exhibited a circadian rhythm, peaking at 2:00 AM.
- Collagen/epinephrine cartridge closure time was significantly longer at 2:00 AM compared to 8:00 AM (p=0.004).
- Fibrinogen levels and factor VIII activity were lowest during nighttime hours (10:00 PM - 4:00 AM).
Conclusions:
- A distinct circadian rhythm exists in human platelet function, measurable with the PFA-100 under high shear conditions.
- The PFA-100 is a practical and effective tool for studying circadian variations in platelet function.
- These findings highlight the importance of considering diurnal variations in platelet activity in physiological and pathological contexts.
Abstract:
The circadian rhythm plays an important role in the physiology and pathophysiology of the human being. Previous investigations revealed a circadian rhythm also in platelet function but these investigations have been limited to optical aggregometry with platelet-rich plasma and low shear stress. The aim of the present study was to further elucidate the impact of the circadian rhythm on platelet function using whole blood at high shear rates. Platelet function determined with the platelet function analyzer PFA-100 and concentration of fibrinogen and factor VIII activity were measured in healthy volunteers during day and night time, and even at shorter intervals (8:00, 12:00, 16:00, 20:00, 22:00, 0:00, 2:00, 4:00, 6:00 h). The mean peak closure time of the collagen/epinephrine cartridge of the PFA-100 was maximal at 2:00 h (192.0 +/- 57.4 s) and declined to the trough value at 8:00 h (140.1 +/- 33.4 s) (p = 0.004). This was paralleled by data from the collagen/ADP cartridge (22:00 h: 99.1 +/- 38.5 s/2:00 h: 81.3 +/- 16.7 s; p = 0.049). Concentration of fibrinogen and factor VIII activity were lowest during night time (22:00-4:00 h). These findings demonstrate a circadian rhythm in platelet function as measured with the PFA-100. The PFA-100 seems to be an appropriate tool to describe circadian alterations and is easier to use than optical aggregometry in analogous studies.
