Copeptin in the differential diagnosis of the polydipsia-polyuria syndrome – revisiting the direct and indirect water deprivation tests

Copeptin decrease from admission to discharge has favorable prognostic value for 90-day events in patients admitted with dyspnea

“…Indeed the reason of copeptin variations during hospitalization depends on multiple factors (diseases, therapies, comorbidities, etc). The variation of copeptin level could be linked with loop diuretic doses as analyzed by Balling et al [26], or reflect sodium and water abnormalities [27,28], very common in heart failure patients. Otherwise a great reduction of copeptin was obtained in patients treated with more adequate or intensive therapy or it depends on patient response.…”

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

“…Up now, few literature data exist on its utilization in the PPS differential diagnosis and all derive from adult case series. [12][13][14][15][16][17][18][19][20][21] Most reports conclude that the baseline plasma copeptin level is indeed useful in NDI distinction from other forms of polyuria-polydipsia, whereas its levels after WDT may be helpful in the differential diagnosis between CDI and PP.…”

“…children affected by PP had diurnal and nocturnal polyuria/polydipsia, and none of them had abnormal psychomotor development; they were redirected to their paediatricians with the indication of fluid restriction to maximum 40-50 mL/kg/day.5 | D ISCUSS I ONThe differential diagnosis of the polyuria-polydipsia syndrome (PPS) in childhood is often challenging as the clinical conditions included within this spectrum display overlapping features; as the actual routine biochemical evaluations are not always helpful, the diagnostic pathway often requires the utilization of the WDT and DDAVP test, whose interpretation in some cases is difficult. In the diagnostic pathway, the serum AVP analysis is not routinely performed, for its in vitro instability and time-consuming results; its surrogate copeptin (CT-proAVP), released in an equimolar 1:1 ratio, has been recently introduced in the adult population as promising tool for the PPS differential diagnosis[12][13][14][15][16][17][18][19][20][21] . Fenske et al 12 have suggested a baseline plasma copeptin level <2.6 pmol/L as cut-off level for the CCDI diagnosis and a <5 pmol/L cut-off level, after 16 hours water deprivation, for discriminating PCDI from PP; conversely, basal plasma copeptin levels >20 pmol/L suggest a NDI.…”

Management of diabetes insipidus and adipsia in the child

“…Although in the last few years measurement of plasma copeptin e either at baseline or during different tests e has been proposed as a reliable stable surrogate for plasma AVP [36], the diagnostic cutoff values are still to be validated. Despite urinary AQP2 has also been described in the differential diagnosis of CDI versus NDI 20 years ago [37], its current use in daily practice is very limited.…”