Clinical features 

• Mild ( K+ 3.0–3.5 mmol/L): asymptomatic.
• Muscle: muscular weakness, tiredness. 
• Heart:
  • ventricular ectopic beats, arrhythmias,
  • arrhythmogenic effects of digoxin may be potentiated. 
• Gut: Paralytic ileus. 
• Kidney: 
  • renal tubular damage (hypokalemic nephropathy)
  • acquired nephrogenic diabetes insipidus → resulting in polyuria and polydipsia.

SAQ. A 28 years old male came with repeated weakness of all four limbs. You reviewed his investigation profile for the last 1 year and found that there is persistent hypokalemia. How will you clinically evaluate and investigate this patient to reach the diagnosis? 

Recurrent and/or Persistent hypokalemia: D/D

• Drug induced: Diuretics, Corticosteroids, beta agonist, laxative abuse, 
• Conn syndrome
• Cushing’s Syndrome
• Renal artery stenosis
• Renal tubular acidosis – eg Sjogren syndrome, Wilson disease etc
• Persistent diarrhea, vomiting 
• Intestinal fistula
• Liddle’s syndrome 
• Gietleman’s syndrome
• Hypokalemic periodic  paralysis 

Clinical Evaluation

• medications (e.g., laxatives, diuretics, antibiotics), 
• diet and dietary habits (e.g., licorice)
• symptoms that suggest a particular cause (e.g., periodic weakness, diarrhea).

Investigation

Initial:

• electrolytes, BUN, creatinine,
• serum osmolality,
• Mg2+, Ca2+,
• complete blood count, and
• urinary pH, osmolality, creatinine, electrolytes
• Urinary calcium
• TSH, FT4

Patients with Liddle’s syndrome classically manifest severe hypertension with hypokalemia, unresponsive to spironolactone yet sensitive to amiloride.

Management 

The goals of therapy in hypokalemia are to prevent life-threatening and/or serious chronic consequences, to replace the associated K+ deficit, and to correct the underlying cause and/or mitigate future hypokalemia

• Treatment of the cause, if possible. 
• If the problem is redistribution of potassium into cells, reversal of the process.
  • correction of alkalosis, stop beta agonist etc
• Potassium replacement: 

• • slow-release potassium chloride tablets

• acute condition:

1. 1. IV potassium chloride. 
   2. The rate of administration depends on the severity of hypokalaemia; presence of cardiac or neuromuscular complications. 
   3. generally not exceed 10 mmol of potassium per hour. 
   4. with severe, life-threatening hypokalemia, infusion rates up to 20 mmol/hr with continuous cardiac monitoring. 

• In presence of metabolic acidosis: 

• • alkaline salts of potassium (potassium bicarbonate) orally. 

• If hypomagnesemia: 

• • replacement of magnesium 

• Potassium-sparing diuretics, such as amiloride: correction of hypokalemia, hypomagnesaemia and metabolic alkalosis, especially when renal loss of potassium is the underlying cause.
• Frequent plasma potassium monitoring to avoid hyperkalemia