Week 5 - Sodium Imbalances

Question 1

What is hyponatremia? (4)

Answer 1

• low serum sodium:
• serum is more flute than normal, osmolality low (can be due to lack of Na or too much water)
• relative excess of water in relation to sodium
• low osmolality causes fluid to shift from the plasma where water concentration is high into cells where it is low

Question 2

What are clinical manifestations of hyponatremia? (6)

Answer 2

• non-specific CNS dysfunction R/T cells (brain cells) swelling with fluid
• malaise
• anorexia
• N & V
• Headaches -> confusion -> lethargy -> seizures -> coma
• severe swelling in brain -> herniation/fatal

Question 3

What is the etiology of hyponatremia? remember that etiology means cause. (4, 7)

Answer 3

1. gaining more water than salt
2. diseases that cause too much ADH to be secreted
   - kidney reabsorbs water and not Na
   - SIADH
   - Pain, nausea, stressors (common in post-op patients)
3. Excessive IV fluids without Na (D5W) or hypotonic solutions 0.45% NS
4. Excessive water drinking

Question 4

What medications are administered for hyponatremia?

Answer 4

• diuretics

Question 5

What is hypernatremia? (4)

Answer 5

• high serum sodium
• relative excess of sodium in relation to water… high osmolality (can be due to lack of water or too much Na)
• High Na in plasma (elevated serum osmolality) pulls fluids out of IF and ICF
• then cells shrink and becomes dysfunctional

Question 6

What are the clinical manifestations of hypernatremia? (5)

Answer 6

• again CNS dysfunction but now because of shrinking brain cells
• lethargy -> agitation -> seizures -> coma
• intense thirst (diminished in elderly)
• Oliguria
• severe hypernatremia = death

Question 7

What happens in oliguria? (2)

Answer 7

• decreased urinary output
• kidney holds onto water

Question 8

What is the etiology of hypernatremia? (2, 9)

Answer 8

1. Gain of salt more than water
   - highly concentrated tube feeds
   - hypertonic IV fluids (3% NS)
   - older folks with diminished thirst
2. Loss of more water salt
   - conditions (diabetes Insipidus): lack of ADH so water is not reabsorbed
   - prolonged vomiting
   - diarrhea
   - diaphoresis

Question 9

What are treatments for hypernatremia caused by water loss? (2)

Answer 9

• treat the underlying cause
• replace with isotonic fluid like NS 0.9%

Question 10

What are treatments for hypernatremia caused by excess sodium? (3)

Answer 10

• treat underlying cause
• replace with salt-free IV solution like D5W
• excrete sodium with diuretics

Question 11

What are treatments for hyponatremia caused by water excess? (2)

Answer 11

• fluid restriction
• if seizures can use small amount of saline 3% to increase sodium (dangerous)

Question 12

What are treatments for hyponatremia caused by fluid loss?

Answer 12

• IV replacement of fluid containing sodium

Question 13

Here are lab values reflecting fluid and electrolyte balance.

Answer 13