Hyponatremia

Question 0

How does hyponatremia develop?

Answer 0

When water intake>ability to excrete

Question 1

Define hyponaremia

Answer 1

Serum sodium <135mEq/L

Question 2

What is req for the collecting duct to be water permeable?

Answer 2

ADH

Question 3

Free H2O clearance equation

Answer 3

Urine vol*(1-(urine(NA+K)/serum (Na+K))

Question 4

Non-phys and physiologic regulators of ADH secretion?

Answer 4

Non: Pain, nausea, hypoxia, drugs (morphine)
Phys: Low effective arterial blood volume and low BP

Question 5

Causes of low serum Na with osm <100

Answer 5

Excessive water intake (primary polydipsia)

Question 6

Causes of low serum Na with >100osm/kg

Answer 6

Vol overload: CHF, Cirrhosis, nephrosis (edema, rales)
Euvolemic: endocrinopathies, thiazides, SIADH, hypothyroid
Vol deplete (orthostatic): Na loss (renal or extra-renal)

Question 7

Min normal tonicity value?

Answer 7

275

Question 8

When do you suspect SIADH?

Answer 8

Uosm>100, UNa>40, low serum uric acid

Question 9

Clinical manifestations of hypotonic hyponatremia

Answer 9

Acute: presents with symptoms of Na 125mEq/L
Chronic: symptoms when Na hits seizures/come at <115

Symptoms:
-Headache, seizures, coma, muscle twitching

Question 10

Danger of rapid correction of hypotonic hyponatremia

Answer 10

Central Pontine Myolinolysis (no fine motor skills) correct at rate that matches creation of hyponatremia

Question 11

What do you give for hypovolemic hyponatremia?

Answer 11

Give volume: saline (NaCl and H2O)

Question 12

What do you do for euvolemic hyponatremia?

Answer 12

Correct underlying disorder, restrict water, block ADH effect with drugs

Question 13

How do you treat hypervolemic hyponatremia?

Answer 13

Water restriction, diuretics, block ADH

Question 14

Vaptans

Answer 14

Vasopressin antagonists:

• corrects Na problem in lab, but pts dont do better
• for euvolemic and hypervolemic hyponatremia