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Causes of Hypokalemia

46-3 Causes of Hypokalemia (Ref. Hari. 18th ed., Pg- 352, table 45.4)
  1. Decreased intake
  2. Redistribution into cells
    1. Acid-base - Metabolic alkalosis
    2. Hormonal
      1. Insulin
      2. Beta 2- agonists
      3. Alpha antagonists
    3. Anabolic state
      1. Vitamin B12 therapy
      2. Total parenteral nutrition
    4. Other:
      1. Pseudo-hypokalemia
      2. Hypothermia
      3. Barium toxicity
  3. Increased loss
    1. Nonrenal:
      1. Diarrhea
      2. Sweat
    2. Renal
      1. Increased distal flow: diuretics, osmotic diuresis, salt-wasting nephropathies
      2. Increased secretion of potassium
  4. Mineralocorticoid excess
    1. Primary & Secondary hyperaldosteronism,
    2. Apparent mineralocorticoid excess (licorice, chewing tobacco, carbenoxolone),
    3. Congenital adrenal hyperplasia,
    4. Cushing's syndrome,
    5. Bartter's syndrome
  5. Distal delivery of non-reabsorbed anions: vomiting, proximal (type 2) renal tubular acidosis, Glue-sniffing
  6. Other: Amphotericin B, Liddle's syndrome, Hypomagnesemia

Clinical Features

  1. Muscle Weakness
    1. Fatigue, myalgia, and muscular weakness of the lower extremities
    2. Hypoventilation (due to respiratory muscle involvement), and eventually complete paralysis.
    3. Impaired muscle metabolism and the blunted hyperemic response to exercise associated with profound K+ depletion increase the risk of rhabdomyolysis.
    4. Smooth-muscle function may also be affected and manifest as paralytic ileus.
  2. Cardiac arrhythmia
  3. Polyuria
  4. ECG.
    1. Flattening or inversion of the T wave,
    2. Prominent U wave,
    3. ST-segment depression,
    4. Prolonged QT interval.
    5. Prolonged PR interval,
    6. Increased risk of ventricular arrhythmias
Hypokalemia: Treatment = Potassium supplementation. Slow I/V infusion, 10-20 mmol//l/hr (AIIMS May 13) (Ref. Hari. 18th ed., Pg- 354)




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