Hyperkalemia

By | 2011-08-09

10. What concentration of potassium results in a diagnosis of hyperkalemia?

The serum potassium concentration should be > 5.5 mEq / L to diagnose hyperkalemia.

11. What are the most common causes of hyperkalemia in dogs and cats?

1. Increased intake

• Most commonly due to excessive potassium chloride or inadequate mixing in intravenous fluids

• Transcellular shifts

  • Lack of insulin
  • Acute mineral acidosis (HC1, NH4C1)
  • Acute tumor lysis syndrome
  • Massive tissue injury
  • Digitalis toxicity
  • Reperfusion after thromboembolism

2. Decreased renal excretion

• Urethral obstruction

• Anuric or oliguric renal failure (requires significant reduction in glomerular filtration rate and urinary output)

• Adrenal insufficiency

• Drugs

  • Angiotensin-converting enzyme (ACE) inhibitors
  • Potassium-sparing diuretics
  • Nonsteroidal antiinflammatory drugs (NSAIDs)
  • Heparin

12. What are the clinical manifestations of hyperkalemia?

Weakness and neuromuscular paralysis (without CNS disturbances), suppression of renal ammoniogenesis (which may result in metabolic acidosis), and bradycardia commonly result from hyperkalemia.

13. What are the most common electrocardiographic (ECG) signs of hyperkalemia?

Decreased heart rate, decreased P-wave amplitude, and increased QRS duration are the most sensitive ECG indicators of hyperkalemia. The spiked T-wave, which is classically considered an electrocardiographic sign of hyperkalemia, is rarely recognized clinically.

14. What is pseudohyperkalemia?

Circulating blood cells, particularly platelets and white blood cells, release potassium when activated or destroyed. Potassium is normally released from platelets during the clotting process. In dogs with thrombocytosis, mild to moderate increases in serum potassium are observed. This in vitro event has no physiologic effect in the animal. Erythrocytes in dogs and cats contain little intracellular potassium. Thus, hemolysis does not increase serum potassium concentrations.

15. What are the goals in treating hyperkalemia?

• To reverse the toxic effects on the heart.

• To shift potassium from the extracellular fluid compartment into the ICF compartment.

• To lower total body potassium levels.

16. How is hyperkalemia managed?

• Discontinue potassium administration (e.g., intravenous fluids, salt substitutes, potassium chloride, potassium penicillin).

• Administer calcium gluconate (2-10 ml of 10% solution) (reverses toxic effects on the heart).

• Consider administering sodium bicarbonate (0.25-1 mEq / kg IV) or 25% dextrose (1 gm / kg IV) with regular insulin (0.5-1.0 U / kg IV) to shift potassium from the extracellular fluid into the ICF

• Administer bolus potassium-free intravenous crystalloids to dilute extracellular fluid potassium.