FP26-1 Copeptin in the Differential Diagnosis of Hyponatremia in Hospitalized Patients ‘The Co-MED-Study'

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: FP26-Neuroendocrinology
Sunday, June 16, 2013: 10:45 AM-11:15 AM
Presentation Start Time: 10:45 AM
Room 130 (Moscone Center)

Poster Board SUN-144
Nicole Nigro*1, Bettina Winzeler1, Isabelle Suter-Widmer1, Birsen Arici1, Martina Bally2, Claudine Angela Blum2, Philipp Schuetz2, Christian Nickel1, Roland Bingisser1, Andreas Bock3, Andreas Huber2, Beat Mueller2 and Mirjam Christ-Crain1
1University Hospital Basel, Basel, Switzerland, 2Kantonsspital Aarau, Aarau, Switzerland, 3Kantonsspital Aarau, Aarau
Background: Hyponatremia is common and its differential diagnosis challenging. An important mechanism is adequately or inadequately secreted plasma arginine vasopressin (AVP). From a pathophysiological point of view, the level of plasma vasopressin may help in the differential diagnosis. Copeptin is secreted in an equimolar ratio to AVP and is easier and more reliable to measure.

Design and Setting: Prospective multicentre observational study in two tertiary referral centers in Switzerland.

Methods: We show data of 175 consecutive patients with severe hypoosmolar hyponatremia (Na<125mmol/L) at presentation to the emergency department. In all patients, a standardized diagnostic evaluation was performed and patients were treated according to a diagnostic algorithm with fluid restriction or physiologic saline administration, respectively. Copeptin levels were compared between different aetiologies of hyponatremia.

Results: Median plasma copeptin levels in patients with primary polydipsia (n=17) were 3.8 [IQR 2.38- 5-79] pmol/L, in patients with diuretic induced hyponatremia (n=45) 13.21 [IQR 7.32-57.28] pmol/L, in patients with SIADH (n=56) 13.03 [IQR 5.61- 28.80] pmol/L, in patients with hypervolemic hyponatremia (n=25) 28.15 [IQR 10.85- 64.45] pmol/L and in patients with hypovolemic hyponatremia (n=32) 55.05 [IQR 23.42-126.1] pmol/L (p [KRUSKAL WALLIS] <0.0001). Copeptin levels were higher in patients requiring saline infusion (n=77) compared to patients requiring fluid restriction (n=98) (27.0 [IQR 10.0- 78.05] vs. 12.24 [IQR 5.35- 29.65], p< 0.001). A copeptin level >70 pmol/L allowed a diagnosis of hypovolemic or diuretic induced hyponatremia requiring saline infusion with a specificity of 91%. Similarly, a copeptin/urinary sodium ratio >1.84 could identify patients with a clear need of saline infusion with a specificity of 90.2%.

Conclusion: Plasma copeptin levels add diagnostic information in the differential diagnosis of patients with severe hyponatremia and identify a subset of patients with clear need for saline infusion. Used in combination with clinical algorithms, copeptin may provide a new tool for a more rapid and targeted treatment in patients with severe hyponatremia.

Disclosure: PS: Coinvestigator, Thermofischer (Brahms AG). BM: Consultant, BRAHMS/Thermofisher. Nothing to Disclose: NN, BW, IS, BA, MB, CAB, CN, RB, AB, AH, MC

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

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