Lecture 7 - Hyper and Hyponatremia

Question 1

Iso-osmolal Hyponatremia occurs when some ______ (impermeant or permeant?) osmole retains free water around it. Thus, serum osmolarity will typically be ______ or slightly high.

Answer 1

Impermeant

Normal or slightly high

Question 2

Pseduohyponatremia is really just an artifact of the way Na+ is measured in the serum. It occurs with high levels of serum _____ and _____ that effectively distort the measured Na+ content. Look for patients with _______ and Hypertriglyceridemia.

Answer 2

Protein and Lipids

Multiplemyeloma

Question 3

Dilutional Hyponatremia is caused by excess water consumption (or Beer potamania/Tea and Toast ish) and impaired urinary ______.

Answer 3

Dilution

Question 4

Decreased excretion of “free water” from the kidneys is ALWAYS caused by high levels of _____. In these cases, what would you expect to be true of Urine osmolarity?

Answer 4

ADH

It would be inappropriately HIGH

Question 5

Low Effective Circulating Volume refers to low plasma volume in the vasculature. Keep in mind this can occur in a Hypovolemic-Hyponatremic (be on the lookout for patients using ______ diuretics) manner OR in a Hypervolemic-Hyponatremic manner. What are the 3 main causes of the latter?

Answer 5

Thiazide diuretics

1. Cirrhosis
2. CHF
3. Nephrotic Syndrome

Question 6

When correcting for chronic HYPO-osmolal hyponatremia, the target increase in serum Na+ should be ___-___ mEq/L/day. Increases > ____-____mEq/L/day are associated with risk of _____.

Answer 6

4-6mEq/L/day

10-12mEq/L/day

ODS

Question 7

Treatment of Hypovolemic Hyponatremia involves volume resuscitation with saline. The kidneys may start excreting Free Water, which can lead to Overcorrection. If overcorrection is suspected, give ______ (desmopressin - and ADH analog).

Answer 7

DDAVP

Question 8

Treatment of Hypervolemic Hyponatremia is with ______ diuretics. Where/what do these act on??

Answer 8

Loop diuretics (e.g. Furosemide).

They act on the TAL, blocking the Na/K/2Cl co transporter.

Question 9

HYPERnatremia is always about ____ ____ depletion, for which there are two main causes:
1. _____ diuresis (increase in mannitol or glucose in the urine).

2. _____ diuresis (lack of ADH effect)

Answer 9

Free Water

1. Osmotic
2. Water

Question 10

In Central Diabetes Insipidus (Central DI), the hypothalamus is not producing enough _____ –> inappropriate loss of free water –> hypernatremia.

In Nephrogenic DI, there is a mutation in the ___ receptor or in ______ –> ADH cannot bind and cause its effect –> inappropriate free water loss –> hypernatremia.

Answer 10

ADH

V2 receptor or Aquaporins

Question 11

To differentiate between Central DI, Nephrogenic DI, and other causes of Hypernatremia, perform a _____ _____ test.

If urine osmolarity is HIGH –> What is it not?

If urine Osmolarity is LOW –> give _______ to differentiate between Central and Nephrogenic DI –> no change after administering ____ = _______ DI; Increase of > 600mOsm = ______ DI (anywhere in between no change and 600mOsm = mixed).

Answer 11

Water Deprivation test

If Urine Osmolarity is high –> it’s not DI

If low –> give DDAVP (desmopressin) –> no change after DDAVP = Nephrogenic DI; increase in urine osm > 600 = Central DI; anywhere in between is Mixed Central/Nephrogenic

Question 12

Treatment of Nephrogenic DI can sometimes include ______, bc prostaglandins can oppose ADH.

Answer 12

NSAIDs

Question 13

How does the rate of correction differ between the treatment of Hyper vs Hyponatremia?

Answer 13

Hyper –> lower serum Na+ concentration by 10-12mEq/L/day is the target!

Hypo –> 4-6 is the target, and always less than 10-12 to avoid ODS!