Fluid and Electrolyte Cases Part 1

Question 1

Number 1 cause of euvolemic hyponatremia

Answer 1

Syndrome of Inappropriate ADH Secretion (SIADH)

Question 2

SIADH Med Causes

Answer 2

Antineoplastic agents
Antipsychoatics (Haloperidol, thioridazone, chlorpromazine)
CARBAMAZEPINE
DESMOPRESSIN
NSAIDS
OPIATES
SSRI/SNRI (fluxetine, duloxetine)
Tricyclic antidepressants (Amitriptyline, imipramine)

Question 3

Asymptomatic/Chronic Rate of Correction of Sodium

Answer 3

Increase Na by less than or equal to 0.5 mEq/h

Less than 10-12 mEq/24 hour period

Question 4

Symptomatic/Acute Rate of Correction of Sodium

Answer 4

• Seizures, alterned mental status
  Increase Na by 1-2 mEq/h for first few hours
  No more than 12 mEq/ 24 hours

Question 5

Consequences of correcting sodium too quickly:

Answer 5

It affects the brain

Myelin sheath will disconnect from the brain cells and cannot be reconnected

Question 6

Total Body Water in Men vs Women

Answer 6

M: 0.6kg
W: 0.5kg

Question 7

Hypotonic Hypovolemic

Answer 7

IV 0.9% saline
Severly symptomatic - 3% saline
Do hourly monitoring

Question 8

Hypotonic Euvolemic

Answer 8

Fluid resitriction (less than 1000 mL/day)
IV 3% saline if severe symptoms (+/- loop diuretic)

Question 9

Demecloycyline

Answer 9

Hypotonic Euvolemic
Inhibits action of ADH
Not used very often and it takes a while to work

Question 10

Urea

Answer 10

Hypotonic Euvolemic

Contraindication in renal or hepatic failure

Question 11

Sodium Chloride

Answer 11

Hypotonic Euvolemic
Often combined with loops
Avoid in HF pts

Question 12

Vaptans

Answer 12

ADH receptor antagonists
Free water excretion and increase sodium concentrations
DO NOT USE IN HYPOVOLEMIC PTS

Question 13

ConIVaptan (Vaprisol)

Answer 13

Local site rxn

Long lasting and can correct too quickly

Question 14

Tolvaptan (Samsca)

Answer 14

V2 only
Risk of overcorrection here too
Chronic

Question 15

Hypotonic Hypervolemic

Answer 15

Treat underlying conditions like HF (ACEi/ARB, Digoxin)
Fluid restriction less than 1000 mL/day
AVP Receptor antagonists

Question 16

Hypovolemic Hypernatremia + Hemodynamic instability (hypotension, tachycardia) Treatment

Answer 16

0.9% NaCl 200-300 mL/day continuous infusion until stability is restored
Then hypotonic fluid continuous infusion to correct water deficit (0.45% NaCl or D5W)

Question 17

Euvolemic Hypertnatremia + Central Diabetes Insipidus

Answer 17

ADH Replacement (Desmopression start at 10 mcg at night)
Measure Na q 3-4 days initially, then q 2-4 months

Question 18

Euvolemic Hypenatremia + Nephrogenic diabetes insipidus

Answer 18

Does not respond to ADH
Need to correct underlying disease
Use thiazide and salt restriction

Question 19

Hypervolemic hypertnatremia

Answer 19

Loop diuretic (Lasix 20-40 mg IV Q6)
D5W based on water deficit