ELECTROLYTE DISORDERS-HYPONATREMIA

Question 1

Serum sodium concentration less than

Answer 1

135 mEq/L (135 mmol/L)

Question 2

Most common electrolyte abnormality is seen in what patients and why

Answer 2

hospitalized patients

often caused by hypotonic fluids

Question 3

(c) Usually reflects excess water -retention relative to sodium rather than sodium -deficiency
* NOT A FLASHCARD. JUST ANOTHER BULLET*

Answer 3

(d) Mismanagement can result in neurologic catastrophes from cerebral osmotic
demyelination

NOT A FLASHCARD. JUST ANOTHER BULLET`

Question 4

Evaluation starts with a careful history for

Answer 4

1) new medications,

2) changes in fluid intake (polydipsia, anorexia, intravenous fluid rates and
composition) ,

3) fluid output (nausea and vomiting, diarrhea, ostomy output, polyuria, oliguria,
insensible losses)

Question 5

Signs and symptoms

Generally

Answer 5

(a) Whether hyponatremia is symptomatic depends on its severity and acuity

(b) Acute disease that has developed over hours to days can be severely symptomatic
with relatively modest hyponatremia.

(c) Mild hyponatremia (sodium concentrations of 130-135 mEq/L) is usually
asymptomatic

Question 6

Signs and symptoms

Mild symptoms

Answer 6

1) Nausea

2) Malaise

Question 7

Signs and symptoms

Moderate symptoms

Answer 7

1) Headache
2) Lethargy

3) Disorientation

Question 8

Signs and symptoms

Severe symptoms

Answer 8

1) Respiratory arrest
2) Seizure
3) Coma
4) Permanent brain damage,
5) Brainstem herniation
6) Death

Question 9

Laboratory findings

Answer 9

(a) Serum electrolytes
1) Serum sodium concentration less than 135 mEq/L (135 mmol/L)
(b) Creatinine
(c) Urine sodium

Question 10

Imaging

Answer 10

None

Question 11

Treatment

Answer 11

(a) Restriction of free water and hypotonic fluid intake is the initial step in hyponatremia
management.

(b) Free water intake should generally be less than 1-1.5 L/day,

1) more severe free water restriction may be necessary in patients with minimal free
water clearance
2) Hypertonic saline may be necessary in patients with negative free water
clearance.

Question 12

Complications

Answer 12

(a) Most serious complication of hyponatremia is iatrogenic cerebral osmotic
demyelination from overly rapid sodium correction.

1) Generally catastrophic and irreversible.

Question 13

Follow up

Answer 13

(a) Symptomatic and severe hyponatremia generally require hospitalization for
1) monitoring of fluid balance and weights,
2) treatment
3) frequent sodium checks