Use of midregional pro-atrial natriuretic peptide in early determination of volume status in hyponatremic patients

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 723-757-Renin-Angiotensin-Aldosterone System/Endocrine Hypertension
Bench to Bedside
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-739
Karin Olsson*1, Sofia Enhörning2, Bertil Öhlin3 and Olle Melander2
1Department of Endocrinology, Lund, Sweden, 2Center for Emergency Medicine, Malmö, Sweden, 3Department of Emergency Medicine, Lund, Sweden
Background: Hyponatremia is the most common electrolyte disturbance. Treatment options depend on finding the underlying cause of the condition, and on patient volume status. An accurate assessment of volume status in the Emergency Department is however often difficult, especially the differentiation between patients with mild hypovolemia versus euvolemia. The use of biomarkers could aid early determination of volume status and facilitate management.

 Methods: Blood samples were collected from an unselected patient population at entry to the Emergency Department. If P-Na ≤ 125 mmol/L the plasma sample was frozen for further analyses. A comprehensive assessment of volume status, the underlying aetiology to their hyponatremia and treatment effect was made after patient discharge, and mid-regional pro-atrial natriuretic peptide (MR-proANP) levels were analyzed in the admission blood sample. Patient evaluation was performed blinded for ANP results.

 Results: A total of 81 patients were included in the study and of these patients a well substantiated volemic state (hypo- eu- or hypervolemia) could be established in 72 patients (mean age 76 years, 65% women, median P-Na 119 mmo/L).

A significant association was observed between MR-proANP levels and volemic state in linear regression analysis (beta-coefficient 0.30 SD of MR-proANP per volemia class, 95% CI 0.15-0.44, p=0.0001). In a multivariate backward elimination model (entering age, gender, thiazide or loop diuretics, heart failure, cirrhosis, oedema, gastrointestinal losses and MR-proANP) MR-proANP remained significantly related to volemia state (beta-coefficient 0.18 SD of MR-proANP per volemia class, 95% CI 0.04-0.32, p=0.012).

As the distinction between mild hypovolemia and euvolemia is the clinically more predominant issue, data was also analyzed with respect to hypo- or euvolemia (n=59) using logistic regression. In a crude analysis, MR-proANP was significantly related to euvolemia (OR: 2.54 per SD of MR-proANP, 95% CI 1.32-4.86, p=0.005) and remained so after the multivariate backward elimination model (OR:2.45 per SD of MR-proANP, 95%CI 1.22-4.91, p=0.012.)

 Conclusions: MR-proANP may be of value in early and objective determination of volume status in hyponatremic patients facilitating management and choice of treatment regimen.

Nothing to Disclose: KO, SE, B, OM

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