Clinical Notes : Cardiovascular Disease

111. Hyperkalemia

Hyperkalemia

 
 

Definitions

  • Hyperkalaemia is defined as a potassium level > 5,0 - 5.5 mEq/L in adults

    • the range in infants and children is age-dependent

  • Levels higher than 7 mEq/L can lead to significant hemodynamic and neurologic consequences

  • Levels exceeding 8.5 mEq/L can cause respiratory paralysis or cardiac arrest and can quickly be fatal

Etiology

  • Excess intake

    • does not include eating too many bananas

  • Decreased excretion

    • Chronic kidney disease alone generally will not cause hyperkalemia until the eGFR is less than 20-25 mL/min.

  • Increased released from cells

Most common : 

  • Acute kidney failure

  • Chronic kidney disease

other :

  • Addison's disease (adrenal insufficiency)

  • Angiotensin II receptor blockers (ARBs)

  • Angiotensin-converting enzyme (ACE) inhibitors

  • Beta blockers

  • NSAIDs (in patients with pre-existing renal insufficiency or cardiovascular disease)

  • Dehydration

  • Destruction of red blood cells due to severe injury or burns

  • Excessive use of potassium supplements

  • Type 1 diabetes

Presentation

  • Many individuals with hyperkalemia are asymptomatic

  • When present, symptoms are nonspecific and predominantly related to muscular or cardiac function.

    • Weakness and fatigue are the most common complaints.

  • Occasionally, patients may report the following:

    • Frank muscle paralysis

    • Dyspnea

    • Palpitations

    • Chest pain

    • Nausea or vomiting

    • Paresthesias

 

Physical examination

  • In general, the results of the physical examination alone do not alert the physician to the diagnosis of hyperkalemia, except when severe bradycardia is present or muscle tenderness accompanies muscle weakness, suggesting rhabdomyolysis.

  • Examination findings in patients with hyperkalemia include the following:

    • Vital signs usually normal, except occasionally in bradycardia due to heart block or tachypnea due to respiratory muscle weakness

    • Muscle weakness and flaccid paralysis

    • Depressed or absent deep tendon reflexes

 

Investigations :

In the OOH setting,

  • Urinalysis - If signs of renal insufficiency without an already known cause are present (to look for evidence of glomerulonephritis)

  • Glucose level - In patients with known or suspected diabetes mellitus

  • ECG for signs of hyperkalemia when it is suspected

 

Refer to A+E for

  • Digoxin level

    • If the patient is on a digitalis medication

  • Arterial or venous blood gas

    • If acidosis is suspected

  • Serum cortisol and aldosterone levels

    • To check for mineralocorticoid deficiency when other causes are eliminated

  • Serum uric acid and phosphorus tests

    • For tumor lysis syndrome

  • Serum creatinine phosphokinase (CPK) and calcium measurements

    • For rhabdomyolysis

  • Urine myoglobin test

    • For crush injury or rhabdomyolysis; suspect if urinalysis reveals blood in the urine but no red blood cells are seen on urine microscopy

Management :

Refer to A+E

If the patient has only a moderate elevation in potassium level and no ECG abnormalities, treatment is as follows:

  • Increase potassium excretion using a cation exchange resin or diuretics

  • Correct the source of excess potassium (eg, increased intake or inhibited excretion)

 

In patients with severe hyperkalemia, treatment is as follows:

  • IV calcium to ameliorate cardiac toxicity, if present

  • Identify and remove sources of potassium intake

  • IV glucose and insulin infusion to enhance potassium uptake by cells

  • Correct severe metabolic acidosis with sodium bicarbonate

  • Consider beta-adrenergic agonist therapy (eg, nebulized albuterol, 10 mg, administered by a respiratory therapist); preferred over alkali therapy in patients with renal failure

  • Increase potassium excretion by administering diuretics or gastrointestinal cation-exchange medications

  • Emergency dialysis for patients with potentially lethal hyperkalemia that is unresponsive to more conservative measures or with complete renal failure

 

Medications for increasing potassium excretion include the following:

  • IV saline and a loop diuretic (eg, furosemide), in patients with normal renal function

  • An aldosterone analogue, such as 9-alpha fluorohydrocortisone acetate (Florinef), in patients with hyporeninemia or hypoaldosteronism or solid organ transplant patients with chronic hyperkalemia from calcineurin inhibitor use

  • Cation exchange resin such as sodium polystyrene sulfonate (SPS; Kayexalate) or patiromer; retention enema for hyperkalemic emergencies, oral for patients with advanced renal failure who are not yet on dialysis or transplant candidates

 
 
 
 
 
BMJ Best Practice.png

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The management of hyperkalemia in patients with cardiovascular disease.

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Hyperkalemia in outpatients using angiotensin-converting enzyme inhibitors. How much should we worry?.

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Management of Hyperkalemia in Hospitalized Patients.

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