Hyperkalemia – Diagnosis, Symptoms, and Treatment

What is Hyperkalemia?

Hyperkalemia is the medical term for high serum potassium levels.  This is often caused by kidney disease, high dietary potassium intake, increased cell breakdown, insulin insufficiency, and certain medications (e.g., NSAIDs, beta-blockers).  Rapid elevations in potassium or very high potassium levels may produce muscle weakness, paralysis, cardiac arrhythmias, and even death.  Hyperkalemia that does not respond to medical therapy may require dialysis.

What Causes Hyperkalemia?

Hyperkalemia is caused by transcellular shifts in potassium, cellular breakdown, increased potassium intake, or decreased ability to secrete potassium by the kidneys.  Sometimes, the etiology of hyperkalemia may be a combination of these factors.

Transcellular shifts

Acidic environments in the serum (metabolic acidosis) promote the exchange of hydrogen for potassium at cell membranes – this results in the efflux of potassium out of cells and into the serum.  Insulin normally drives potassium into cells – insulin insufficiency is associated with high serum potassium levels.

Increased cellular breakdown

Cells are generally high in potassium – therefore, when tissue or cells breakdown, they release potassium into the circulation resulting in hyperkalemia.  Situations in which tissue or cells breakdown include:

• Tumor lysis syndrome - acute leukemia or lymphoma treatment
• Trauma
• Rhabdomyolysis – muscle tissue breakdown
• Hemolysis – autoimmune hemolytic anemia, microangiopathic hemolytic anemia

Decreased potassium secretion

The kidneys are responsible for most potassium secretion in the body - the gastrointestinal tract also plays a lesser yet essential role in potassium metabolism.  When the kidneys are injured acutely or chronically, they have difficulty secreting potassium, so patients often develop hyperkalemia.  Medications such as NSAIDs, ACEIs, and ARBs may also reduce the kidneys’ ability to get rid of potassium.  Spironolactone is a potassium-sparing diuretic that can also produce hyperkalemia by decreasing renal potassium secretion.

How Common is Hyperkalemia?

Hyperkalemia is a common electrolyte abnormality in the United States responsible for frequent primary care and emergency department visits.  It is prevalent in critically ill patients in the intensive care unit.  The most common cause is kidney disease.  The condition often requires consultation with a nephrology specialist.

The incidence of hyperkalemia is approximately 1%-10%.  The incidence significantly increases to about 40%-55% in patients with chronic kidney disease.

Signs and Symptoms

Potassium is critical for regulating the electrochemical gradient of cell membranes, particularly in heart and nerve tissues.  Mild hyperkalemia may not produce any symptoms or signs.  More significant elevations in potassium may lead to muscle weakness, paralysis, and cardiac conduction abnormalities.  Cardiac arrhythmias may include atrial fibrillation or severe ventricular arrhythmias such as ventricular tachycardia or fibrillation.  These latter arrhythmias can be fatal.

Diagnosis

Hyperkalemia diagnosis may be suggested based on symptoms and physical examination – but these are typically none specific.  A definitive diagnosis is always made with laboratory confirmation of your serum potassium level.

Other commonly ordered blood tests include a CMP (comprehensive metabolic panel), CBC (complete blood cell count), and thyroid function (TSH, free T4).  Your doctor will also usually screen for diabetes.  If you recently had trauma or performed vigorous exercise, they may obtain a creatine phosphokinase (CPK) level.

If your potassium is significantly elevated, your doctor will likely order an EKG (electrocardiogram) to evaluate the electrical activity of your heart.

Hyperkalemia Medication and Treatment

Acute symptomatic hyperkalemia with EKG changes is typically treated with:

• Calcium gluconate – stabilizes the cardiac cell membranes
• Insulin with dextrose – drives potassium into cells
• Intravenous bicarbonate – drives potassium into cells
• Inhaled Ventolin or ProAir (albuterol) – drives potassium into cells.
• Kayexalate (sodium polystyrene) – gets rid of potassium through the gastrointestinal tract
• Lasix (furosemide) - Loop diuretics removes potassium through the kidneys

Patients who do not respond to these medical treatments may require catheter placement and initiation of dialysis.  Dialysis is a procedure by which a machine substitutes your kidney functions by filtering your blood and removing excess fluid.  Patients with acute kidney injury, significant electrolytes abnormalities, or specific drug intoxications can significantly benefit from dialysis.

Patients with acute kidney injury that have a gradual improvement in kidney function can discontinue dialysis. However, patients with end-stage chronic kidney disease are dependent on dialysis unless they receive a renal transplant.

Long-term treatment of hyperkalemia generally involves avoiding foods that are high in potassium – including bananas, tomatoes, potatoes, and prunes, to name a few.  Patients are also usually counseled about medications that may be contributing, such as NSAIDs, ACEI’s, ARBs, and Aldactone (spironolactone).  It also generally involves adequate hydration and loop diuretics Lasix (furosemide).  Patients may also benefit from a new class of medications called cation exchange polymer – the currently available formulation in the United States is Veltassa (patiromer).

References:

1. Giebisch GH, Wang WH. Potassium transport--an update. J Nephrol 2010; 23 Suppl 16:S97. - https://www.ncbi.nlm.nih.gov/pubmed/21170894
2. Choi MJ, Ziyadeh FN. The utility of the transtubular potassium gradient in the evaluation of hyperkalemia. J Am Soc Nephrol 2008; 19:424. - https://jasn.asnjournals.org/content/19/3/424
3. Kamel KS, Wei C. Controversial issues in the treatment of hyperkalemia. Nephrol Dial Transplant 2003; 18:2215. - https://www.ncbi.nlm.nih.gov/pubmed/14551344