The Circadian Rhythm of Copeptin, the C-Terminal Portion of Arginine Vasopressin

Abstract

Background Several studies have investigated copeptin as a prognostic marker of different acute diseases and as a diagnostic marker in disorders of water and salt homeostasis. However, no data of the normal circadian rhythm of copeptin in healthy subjects are available. Aim To investigate the circadian rhythm of copeptin in healthy subjects under standardized conditions. Methods 19 healthy volunteers aged 18 to 53 years, male and female, were studied in a prospective observational study. In all 19 participants, blood samples for copeptin were taken in regular intervals of 30 minutes for 24 hours after a fasting period of minimum 8 hours. Results The mean values of copeptin showed a circadian rhythm, similar to that described for AVP release, with a trend towards higher levels (5.9 ± 1 pmol/L) at night and early morning between 4 am and 6 am and lowest levels (2.3 ± 0.2 pmol/L) in the late afternoon between 5 pm and 7 pm. This finding was only observed in individuals with initial higher copeptin levels, whereas in individuals with lower basal copeptin levels no circadian rhythm was observed. Conclusion There is evidence for a circadian rhythm in copeptin release during 24 hours, however, of minor extent. These findings suggest that copeptin levels can be determined irrespectively of the time of the day.

Copeptin and its role in the diagnosis of diabetes insipidus and the syndrome of inappropriate antidiuresis

“…While copeptin levels show no significant variation in response to circadian rhythm or digestion, levels significantly decreased from 4.9 to 3.2 pmol/L after oral fluid intake of as little as 200‐300 mL, which has to be considered for interpretation of values in clinical practice.…”

Copeptin role in polyuria‐polydipsia syndrome differential diagnosis and reference range in paediatric age

“…The correlation among AVP levels, serum osmolality and copeptin values is actually well known . In adults, copeptin circadian rhythm is similar to the AVP rhythm, but both peaks and nadirs are delayed, likely for the copeptin longer half‐time (86 minutes vs 44 minutes); this rhythm seems to be slightly blunted in nocturnal polyuria .…”

“…The correlation among AVP levels, serum osmolality and copeptin values is actually well known . In adults, copeptin circadian rhythm is similar to the AVP rhythm, but both peaks and nadirs are delayed, likely for the copeptin longer half‐time (86 minutes vs 44 minutes); this rhythm seems to be slightly blunted in nocturnal polyuria . Recent studies in the paediatric age have explored the possibility to utilize copeptin also as a high‐risk marker for community‐acquired pulmonitis, septic shock, stroke and head trauma; in these studies, copeptin values in the control population were reported between 2.4 and 8.6 pmol/L …”

Distribution of plasma copeptin levels and influence of obesity in children and adolescents

“…Recent studies have evaluated the usefulness of plasma copeptin in the differential diagnosis of hyponatremic and hypernatremic AVP-related disorders, as it represents a stable and rapidly available surrogate of plasma AVP [32][33][34]. It has proven to be very useful in the distinction of hypernatremic conditions (such as CDI, NDI, and PP) and less useful in hyponatremia due to the important overlap between SIADH, hyper-or hypovolemic hyponatremia [35][36][37][38][39][40][41][42][43][44][45][46][47], a finding already reported also in a small number of pediatric patients [42].…”