OnlineMedEd: Nephrology - "Sodium"

Question 1

Disorders of sodium levels are actually disorders of _______________.

Answer 1

free water movement

Free water is not a measure of volume status. It is a measure of tonicity and the ADH pathway.

Question 2

Hyponatremia causes water to move _______________.

Answer 2

from the vessels to the interstitium

Question 3

Hypernatremia causes water to move ______________.

Answer 3

from the interstitium to the vessels

Question 4

Dustyn recommends breaking hyponatremia and hypernatremia into mild, moderate, and severe states. Review the signs/symptoms of each.

Answer 4

• Mild: asymptomatic (discovered incidentally)
• Moderate: nausea, vomiting, headache
• Severe: coma, seizures

Question 5

Review the treatments for mild, moderate, and severe hypernatremia.

Answer 5

• Mild: PO H2O
• Moderate: IV NS
• Severe: D5W or 1/2 NS

Question 6

Review the treatments for mild, moderate, and severe hyponatremia.

Answer 6

• Mild: disease-specific
• Moderate: IVF
• Severe: 3% NaCl

Question 7

Go through the protocol for determining the subtype of hyponatremia.

Answer 7

First, review the formula for serum osmolarity: 2 x Na + glucose/18 + BUN/2.8. It should be 280.
•If it is isotonic hyponatremia (meaning SOsm ~280), then it is likely pseudohyponatremia, caused by fats and proteins.
•If it is hypertonic hyponatremia (meaning SOsm greater than 280), then it is likely due to hyperglycemic hyponatremia.
•If it is hypotonic hyponatremia (meaning SOsm less than 280), then you need to determine if they are volume-up (e.g., CHF), volume-down (dehydration), or euvolemic (RATS).

Question 8

List the treatments for the kinds of hypotonic hyponatremia.

Answer 8

•Volume-up: diuresis
•Volume-down: IVF
• Euvolemic:
- Renal tubular acidosis
- Addison’s disease: corticosteroid and mineralocorticoid replacement
- Thyroid disease:
- SIADH: volume restriction, gentle diuresis, or demeclocyline

Question 9

Urine sodium is a surrogate for ______________.

Answer 9

aldosterone activity

Question 10

Urine osmolarity is a surrogate for ______________.

Answer 10

ADH activity

Question 11

How fast should you correct hyponatremia?

Answer 11

No faster than 0.25 per hour or a max of 6 in one day.

The caveat to this is that you need to give 3% NaCl until the person stops seizing if they are having hyponatremic seizures.