Serum Osmolality Calculator

Sodium Na mEqL Glucose mgdL BUN mgdL Serum Osmolality Calculator Explanation and Clinical Context Serum osmolality reflects the concentration of dissolved particles in plasma and provides an essential window into the body water balance. The major contributors to serum osmolality are sodium glucose and blood urea nitrogen which form the basis of the widely used calculated osmolality formula. Normal serum osmolality ranges from two hundred seventy five to two hundred ninety five milliosmoles per kilogram and values outside this range guide clinicians toward disorders of water homeostasis.

Elevated osmolality is commonly associated with hypernatremia hyperglycemia or renal impairment while low osmolality is encountered in hyponatremia or conditions of excess free water. A calculated to measured osmolality gap may help identify unmeasured osmoles including alcohols toxins or metabolic by products. This calculator supports bedside interpretation by providing an immediate quantitative estimate that can be correlated with clinical findings laboratory measurements and volume status assessment.

Reference Adrogue HJ Madias NE. The challenge of hyponatremia. Journal of the American Society of Nephrology.

Two thousand twelve. Verbalis JG et al. Diagnosis evaluation and treatment of hyponatremia.

American Journal of Medicine. Two thousand thirteen.