MedCalc: Hyponatremia & Hypernatremia

Patient's Sodium :  mEq/L Correct for:
Target Sodium :  mEq/L  Fever?
Rate of Na Correction :  mEq/L/hr  Insensible Loss?
Patient's Weight : 
Patient is a : 
Calculate using : 
 
IVF Rate : 
IV Fluids : 

Classic Formulas:
Hypernatremia
Total H2O deficit (L) =  total body water x ( 1 - desired Na+ )
serum Na+
Hyponatremia
Na+ requirement (mmol) = total body water x (desired Na+ - serum Na+ )
Rate of infusion (cc/hr) =  Na+ requirement (mmol) x 1000
infusate Na+ (mmol/L) x time (hours)

Adrogue Formula:
Change in serum Na+ = (infusate Na+ + infusate K+) - serum Na+
total body water + 1

Infusate Infusate Na+
(mmol/L)
5% NaCl 855
3% NaCl 513
0.9% NaCl (NS) 154
Lactate Ringer's 130
0.45% NaCl (½ NS) 77
0.2% NaCl (¼ NS) 34
5% Dextrose in water (D5W) 0
Total Body Water (in liters) :
Children 0.6 x weight
Women 0.5 x weight
Men 0.6 x weight
Elderly Women 0.45 x weight
Elderly Men 0.5 x weight

Insensible water losses = 500 - 1500 cc/day.
Fever increases insensible water losses by 10% per degree Celsius above 38°, or 100-150 cc/day increase per degree Celsius above 37°.

Adrogue, HJ; and Madias, NE. Primary Care: Hypernatremia. New England Journal of Medicine 2000; 342(20):1493-1499.
Adrogue, HJ; and Madias, NE. Primary Care: Hyponatremia. New England Journal of Medicine 2000; 342(21):1581-1589.

Created: Wednesday, January 23, 2002
Last Modified: