Reliability of basal plasma vasopressin concentrations in healthy male adults.

Objective: The neuropeptides oxytocin (OT) and arginine vasopressin (AVP) play important and interrelated roles in modulating mammalian social behaviour. While the OT system has received considerable research attention for its potential to treat psychiatric symptoms, comparatively little is known about the role of the AVP system in human social behaviour. To better understand the intraindividual stability of basal AVP, the present study assessed the reproducibility of basal plasma AVP concentrations.

Methods: Basal plasma AVP was assessed at four sampling points separated by 8 days, on average, in 16 healthy adult males.

Results: Only one out of six comparisons revealed strong evidence for reproducibility of basal AVP concentrations (visit 2 vs. visit 4: r=0.8, p0.1). The concordance correlation coefficient [0.15, 95% CI (-0.55, 0.73)] also revealed poor overall reproducibility.

Conclusion: Poor reliability of basal AVP concentrations suggests future work covarying AVP with trait markers should proceed with careful consideration of intraindividual fluctuations.