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8 out of 9

Which of the following is a cause of hypokalemia? (PNQ)


B Vit B12 therapy

C Addison disease

D None of the above

Ans. B

Vit B12 therapy


Table 44-4 Causes of Hypokalemia (Ref. Hari ed. 18th Pg-352)

1. Decreased intake

2. Redistribution into cells

a. Acid-base - Metabolic alkalosis

b. Hormonal

i. Insulin

ii. Beta2- agonists

iii. Alpha antagonists

iv. Anabolic state

1. Vitamin B12 therapy

2. Total parenteral nutrition


1. Pseudo-hypokalemia

2. Hypothermia

3. Barium toxicity

Increased loss

1. Nonrenal: a. Diarrhea b. Sweat

2. Renal

a. Increased distal flow: diuretics, osmotic diuresis, salt-wasting nephropathies

b. Increased secretion of potassium

Mineralocorticoid excess

a. Primary & Secondary hyperaldosteronism,

b. Apparent mineralocorticoid excess (licorice, chewing tobacco, carbenoxolone),

c. Congenital adrenal hyperplasia,

d. Cushing's syndrome,

e. Bartter's syndrome

Distal delivery of non-reabsorbed anions: vomiting, proximal (type 2) renal tubular acidosis, Glue-sniffing

Other: Amphotericin B, Liddle's syndrome, Hypomagnesemia

Clinic Features

1. Muscle Weakness

a. Fatigue, myalgia, and muscular weakness of the lower extremities

b. Hypoventilation (due to respiratory muscle involvement), and eventually complete paralysis.

c. Impaired muscle metabolism and the blunted hyperemic response to exercise associated with profound K+ depletion increase the risk of rhabdomyolysis.

d. Smooth-muscle function may also be affected and manifest as paralytic ileus.

2. Cardiac arrhythmia

3. Polyuria

4. ECG.

a. Flattening or inversion of the T wave,

b. Prominent U wave,

c. ST-segment depression,

d. Prolonged QT interval.

e. Prolonged PR interval,

f. Increased risk of ventricular arrhythmias