April 8, 2016 - SG2 - Hyponatremia

Question 1

SIADH

Answer 1

Syndrome of Inappropriate ADH

Occurs when ADH is released under inappropriate circumstances. For example, ADH should be turned off under a serum osmolarity of 280. If we notice that the urine is being concentrated, and the serum osmolarity is low, this would make us think of SIADH.

It is important to note, that you CANNOT diagnose SIADH when the patient is volume-depleted, because under that circumstance ADH is acting as it should.

Question 2

Sodium Levels and Seizures

Answer 2

When the serum concentration of sodium drops below 110, you are in danger of the patient having seizures.

This will further complicate treatment and the patient will need to be intubated at this point and should be avoided if at all possible.

If a patient has acute hyponatremia, it is important to quickly raise the sodium level to above 110, before slowly (12 per day) raising it back into the normal range.

Question 3

Selective Serotonin Re-uptake Inhibitors (SSRI)

Answer 3

A class of drugs that are used as antidepressants.

Also may cause SIADH as a side effect.

Question 4

Primary Polydipsia

Answer 4

A condition in which the patient feels extremely thirsty and drinks a significant amount of water (>3L per day).

Can cause hyponatremia.

Diagnosed by using the water deprivation test in which the kidneys should correct themselves because there is nothing physiologically wrong with them.

Question 5

Calculating Plasma Osmolarity

Answer 5

= 2[Na] + 2[K] + [Glucose] + [BUN]

Question 6

Best Electrolyte for ECF Volume Contraction

Answer 6

Urine Chloride

Not all patients who are hypovolemic will have a low urine sodium, but all patients who are hypovolemic will have a low urine chloride.