What is the significance of hyponatremia in my patient with acute decompensated congestive heart failure (ADCHF)?

Hyponatremia, defined as a serum sodium <135 meq/L, is observed in ~20% of patients hospitalized with ADCHF, and is often dilutional, not “depletional” (ie, not associated with hypovolemia) in this condition1.

In ADCHF, hyponatremia is primarily caused by the production of arginine vasopressin (AVP) (also known as anti-diuretic hormone, or ADH) as a result of decreased perfusion pressures in the aortic arch and renal afferent arterioles, and increased thirst due to the activation of the renin-angiotensin system.  Hyponatremia correlates with the severity of ADCHF and adverse clinical outcomes2.   

 A common approach to dilutional hyponatremia in ADCHF is fluid restriction. Other potential therapies include angiotension converting enzyme inhibitors (by increasing cardiac output and decreasing thirst), loop diuretics (by reducing water reabsorption in the renal distal tubule), and AVP antagonists (eg, tolvapatan, satavaptan)1,3.  Otherwise, in the absence of symptoms, no specific therapy is generally indicated for serum sodium levels ≥ 120mEq/L.

If you liked this post, sign up under MENU and catch future pearls right into your mailbox!

References 

  1. Verbrugge FH, Steels P, Grieten L, Nijst P, Tang WHW, Mullens W. Hyponatremia in acute decompensated heart failure: Depletion versus dilution. J Am Coll Cardiol 2015;65:480-92. https://www.sciencedirect.com/science/article/pii/S073510971407394X?via%3Dihub
  2. Leier CV, Dei Cas L, Metra M. Clinical relevance and management of the major electrolyte abnormalities in congestive heart failure: hyponatremia, hypokalemia, and hypomagnesemia. Am Heart J. 1994;128:564.  https://www.sciencedirect.com/science/article/pii/0002870394906335
  3. Schrier RW, Gross P, Gheorghiade M, Berl T, Verbalis JG, Czerwiec FS, Orlandi C, SALT Investigators. Tolvaptan, a selective oral vasopressin V2-receptor antagonist, for hyponatremia. N Engl J Med. 2006;355:2099. https://www.ncbi.nlm.nih.gov/pubmed/17105757

 

Contributed by Ricardo Ortiz, Medical Student, Harvard Medical School

What is the significance of hyponatremia in my patient with acute decompensated congestive heart failure (ADCHF)?