Jul 28, 2025
Contributor: Taylor Lynch, MD
Educational Pearls:
Dilutional Hyponatremia:
- Occurs when there is an excess of free water relative to sodium in the body.
- Causes a falsely low sodium concentration without a true change in total body sodium.
Commonly seen in DKA:
- Hyperglycemia raises plasma osmolality.
- Water shifts from the intracellular to extracellular space.
- This dilutes serum sodium, creating apparent hyponatremia.
Corrected sodium calculation:
Use tools like MDCALC, or apply this formula:
- Add 1.6 mEq/L to the measured sodium for every 100 mg/dL increase in glucose above 100.
Clinical relevance:
- Considering corrected sodium in DKA is crucial, as the lab value may not be reflective of actual sodium depletion.
- True severe hyponatremia can lead to complications like seizures
- May require treatment with hypertonic saline.
References:
- Fulop M. Acid–base problems in diabetic ketoacidosis. Am J Med Sci. 2008;336(4):274-276. doi:10.1097/MAJ.0b013e318180f478
- Palmer BF, Clegg DJ. Electrolyte and Acid–Base Disturbances in Patients with Diabetes Mellitus. N Engl J Med. 2015;373(6):548-559. doi:10.1056/NEJMra1503102
- Spasovski G, Vanholder R, Allolio B, et al. Diagnosis and management of hyponatremia: a review. JAMA. 2014;312(24):2640–2650. doi:10.1001/jama.2014.13773
