Adenosine Concentration in Patients With Neurally Mediated Syncope, 2022, Antonella Groppelli et al

Background: Either high or low values of adenosine blood level (ABL) can differentiate some forms of neurally mediated syncope (NMS). A rapid method of measurement has recently been developed. The aim of the present study was: (1) to compare ABLs in an unselected population of consecutive patients referred for evaluation of suspected NMS syncope and in healthy controls; and (2) to assess the relative prevalence of low and high adenosine forms among an unselected syncope population.

Method: Whole blood was collected after finger puncture, blood being deposit on a blot paper and adenosine concentration was measured by liquid chromatography/mass spectrometry (LC-MS/MS).

Results: Among 89 control subjects, the median AB( adenosine blood level) value was 0.54 μM (IQR, 0.46–0.65). The lowest 5% and the upper 95% percentile were 0.40 and 0.80 μM, respectively. Compared with healthy subjects, the 146 patients with syncope showed, on average, a higher median ABL value [0.63 (IQR 0.45–0.73, p = 0.04)] and a larger distribution of values. Low ABL values below the 5th percentile were observed in 28 (19%) patients, and, in five controls, p = 0.003 and high ABL values were observed in 26 (18%) patients and five controls, p = 0.009.

Conclusions: ABL is different in patients with suspected NMS than in healthy subjects. Patients with low and high adenosine values account for 19% and 18% of the general population. Thus, low and high ABL limits, as defined in this study, may help to define the purinergic profile of unselected subjects with a clinical diagnosis of suspected NMS.

https://www.frontiersin.org/articles/10.3389/fcvm.2022.900023/full

 

It may be a completely different system, not up to reading the paper, but accumulation of adenosine during the day is said to be what makes you drowsy so one of the processes which regulate sleep. Caffeine binds to the same receptors which is why it keeps you alert and awake.