A 79 Year Old Female Presents With Worsening Confusion Over The Last 2 Days.

A 79-year-old female nursing home resident with moderate dementia presents for worsening confusion over the last 2 days. She just finished antibiotics for a urinary tract infection. Her temperature is 38.1◦C, pulse 110, respiratory rate 18, and blood pressure 118/60 mm Hg. She is disoriented and lethargic.
Examination of the heart, lungs, and abdomen is unremarkable.
Laboratory studies are as follows:
Na 165 mEq/L,
K 4.6 mEq/L,
Cl 118 mEq/L,
HCO3 28 mEq/L,
BUN 31 mg/dL,
Cr 1.1 mg/dL.
Urine specific gravity is >1.030 and urine osmolality is 700 mmol/kg(elevated reflecting reabsorption of free water)
 Her CBC is normal.

1. What will be the initial treatment for this patient?


Demented or delirious patients with an acute febrile illness may not be able to consume enough free water to avoid hypernatremia. Several mechanisms may be at work:

• free water loss due to illness, 
• impaired thirst, and 
• inability to respond to thirst due to cognitive or physical impairments.

Just as with hyponatremia, the hypernatremic patient should not be corrected too quickly. Sudden
changes in plasma sodium may result in cerebral edema. Although there are no standardized
guidelines to direct the correction of hypernatremia, most authorities recommend a maximal correction of 0.5–1 mEq/L/hr. In this patient who appears hypovolemic, the primary concern is to give volume. This can be achieved by normal saline IV bolus.

2. What are the causes Of Hypernatremia?
The causes can be memorized by the menomic of 6 D's shown below:

3. How can you calculate free water deficit in hyovolumic hypernatremic patients?

To calculate the free water deficit in a hypovolemic hypernatremic patient, use the following equation:

Water deficit = 0.6 × weight (kg)× [(plasma Na/140) − 1].

In this patient, assuming a weight of 60 kg:

Water deficit = 0.6 × 60 × [(165/140) − 1]= 6.4 L.