Hypernatremia

Question 1

Eq for Water needed (L) for pts with hypernatremia

Answer 1

Water needed = 0.6 * body weight in Kg * [(actual sodium) - 1]

*make sure you add or remove Na+ while providing H2O slowly

Question 2

How does Hypernatremia occur?

Answer 2

either:

1. ADH is decreased or ineffective
   - Central or nehrogenic DI
2. daily water intake is less than required

*note: hypernatremia is always associated with ↑ed Na+ Osm

Question 3

3 Causes of hypernatremia

Answer 3

1. ↓ TB Na
2. ↑ TB Na
3. Normal TB Na

Question 4

How does ↓ TB Na result in hypernatremia?

Answer 4

↓ TB Na
_______
↓↓ TB Water

total body water loss&raquo_space; total body salt loss
- could be renal or extrarenal

• GI loss (diarrhea, skin loss (burns), diuretic use

Question 5

2 ways normal TB Na results in Hypernatremia

Answer 5

1. Central Diabetes Insipidis (DI)

2. Nephrogenic Diabetes Insipidis (DI)

Question 6

What is the cause of Central Diabetes Insipidus (DI)?

Tx?

Answer 6

ADH deficiency

• give exogenous AVP

Question 7

What is the cause of Nephrogenic DI?

TX?

Answer 7

Coll. ducts cant respond to ADH (cant generate cAMP response)

tx: large fluid intake and use of thiazide diuretic to ↓ urine flow by causing sodium loss and vol depletion.

Question 8

Disorders causing nephrogenic DI?

Answer 8

1. Chronic renal failure
2. hypercalcemia
3. hypokalemia

Question 9

What happens to the cells with hypernatremia?

Answer 9

Cellular dehydration as water shifts out of the cells

(hypernatremia Plasma Na >135 → water flows out of cells → edema

Question 10

Is the absorption of Na in the proximal tubule passive or active?

Answer 10

passive