Management of Hypernatremia in Hyperosmolar Hyperglycemic State (HHS)

Assessment and Monitoring

The American Diabetes Association recommends calculating corrected serum sodium for hyperglycemia to accurately assess the true sodium status, by adding 1.6 mEq to sodium value for each 100 mg/dl glucose >100 mg/dl 1, 2
Effective serum osmolality should be monitored regularly using the formula: 2[measured Na (mEq/l)] + glucose (mg/dl)/18, to guide fluid management decisions 2
Evaluation of adequate fluid resuscitation is crucial, as persistent hypernatremia may indicate inadequate volume replacement or excessive free water losses 3
Assessment of renal function, urine output, and mental status is necessary to guide fluid management decisions, according to the American Diabetes Association 4

The American Diabetes Association suggests switching from D5LR to 0.45% NaCl (half-normal saline) if corrected serum sodium remains elevated, with a target infusion rate of 4-14 ml/kg/h based on hemodynamic status and corrected sodium levels 1, 3, 5
For severe hypernatremia with adequate hemodynamic stability, consideration of 5% dextrose in water (D5W) alternating with isotonic saline may be necessary, with potassium supplementation (20-30 mEq/L) once renal function is assured 3, 6
Target fluid replacement should aim to correct estimated deficits within 24-48 hours, with close monitoring of serum electrolytes, glucose, BUN, creatinine, and osmolality every 2-4 hours 2, 4

The American Diabetes Association recommends continuing insulin therapy but adjusting based on glucose and sodium trends, with a decrease in insulin infusion to 0.05-0.1 U/kg/h (3-6 U/h) when plasma glucose reaches 300 mg/dl in HHS 4, 6, 7
Addition of dextrose (5-10%) to IV fluids when glucose falls below 300 mg/dl is necessary to prevent hypoglycemia while continuing to treat hypernatremia, with a target glucose level between 250-300 mg/dl until hyperosmolarity resolves 6, 7

In elderly patients or those with cardiac/renal compromise, more cautious fluid rates with closer monitoring are recommended, according to the American Diabetes Association 2

The American Diabetes Association recommends using the measured sodium level, not the corrected sodium level, to calculate the effective osmolality in hyperglycemic hyperosmolar state (HHS) patients 8, 9
The standard formula for calculating effective osmolality is: effective osmolality = 2[measured Na+ (mEq/L)] + glucose (mg/dL)/18, which explicitly uses the measured sodium level 8, 9
The diagnostic criterion for HHS requires an effective osmolality >320 mOsm/kg H₂O, calculated using the measured sodium level 8

The measured sodium level is used to calculate the effective osmolality, which reflects the patient's real osmotic state 8, 9
The corrected sodium level is calculated by adding 1.6 mEq to the measured sodium level for every 100 mg/dL of glucose above 100 mg/dL, and is used to determine the type of saline solution to administer 8, 9
The corrected sodium level reflects the patient's true free water deficit, but is not used to calculate osmolality 8, 9

For diagnosing HHS, calculate effective osmolality using the measured sodium level: effective osmolality = 2[measured Na+] + glucose/18 8, 9
For fluid management decisions, calculate the corrected sodium level: corrected Na+ = measured Na+ + 1.6 × [(glucose - 100)/100] [8, 9]