Hypernatremia resident survival guide
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Definition
Hypernatremia is an electrolyte disturbance consisting of an elevated sodium level in the blood. It is defined as a serum sodium concentration exceeding 145 mEq/L.
Causes
Life Threatening Causes
Conditions that may cause death or permanent disability within the next 24 hours
Common Causes
The most common cause of hypernatremia is not an excess of sodium, but a relative deficit of free water in the body. Hypernatremia can be caused by many disease processes and drugs.
- Free water loss in form of diarrhea, diabetes insipidus, diuretics, osmotic agents, insensible losses or impaired thirst response due to any disease process affecting the hypothalamus are common causes.
- Primary sodium excess is a rare cause of hypernatremia and ca be due to sodium salt ingestion or minaralocorticoid excess.
Management
| Serum sodium > 145 | |||||||||||||||||||||||||||||||||||||||||||
| Urine output | |||||||||||||||||||||||||||||||||||||||||||
| Low < 200 | High | ||||||||||||||||||||||||||||||||||||||||||
| High urine osmolality | Urine osmolality | ||||||||||||||||||||||||||||||||||||||||||
| Hypotonic fluid loss GI losses nausea, vomiting, renal losses, diuretics | Low | High | |||||||||||||||||||||||||||||||||||||||||
| Calculate free water deficit (see below) Replace both free water deficit and maintenance fluid Rate of correction no more than 1mEq/L/h Replace 1/2 fluid in 24 hrs, other 1/2 in 24-48 hrs Hypotension - Normal saline, Stable D5W | Negative water deprivation test | Osmotic diuresis | |||||||||||||||||||||||||||||||||||||||||
| Diabetes insipidus | |||||||||||||||||||||||||||||||||||||||||||