HYPERKALEMIA

The medical term for an elevated potassium level in your blood is hyperkalemia. A molecule called potassium is essential for the health of your heart's muscle and nerve cells. Normal blood potassium levels range from 3.6 to 5.2 millimoles per litre (mmol/L), while hyperkalemia is caused by serum potassium levels that are higher than 5.5 mEq/L.

CAUSES

1.Extra-renal causes: Insulin deficiency, acidemia, hyperosmolality, Beta blocker administration, oral or intravenous potassium supplements, penicillin potassium salts, massive blood transfusion, crush injuries, burns, mesenteric or muscular infarction, and tumor lysis syndrome.

2.Renal causes: Chronic renal insufficiency, acute renal failure, hypoaldosteronism, and drugs (e.g., nonsteroidal anti-inflammatory drugs, cyclosporine, heparin, angiotensin-converting enzyme inhibitors, potassium-sparing diuretics) can also cause hyperkalemia.

3.Hyperkalemia is most frequently caused by laboratory error.

CLINICAL FEATURES

Symptoms:

—Confusion 

—Paresthesias/Muscle weakness /numbness in —limbs

—Weakness

—Abdominal pain and diarrhea.

—Chest pain.

—Irregular, fast/fluttering heartbeat

—Nausea/vomiting.

Physical examination findings: 

—Areflexia

—Cardiac arrest

—Ileus

—Paralysis

—Respiratory insufficiency

DIFFERENTIAL DIAGNOSES include pseudo-hyperkalemia, which can occur as a result of hemolysis, extreme leukocytosis, acidosis, thrombocytosis, or cold agglutinins.

EVALUATION

1.Laboratory studies include a serum electrolyte panel, serum BUN, creatinine, glucose, and magnesium levels.

2.Electrocardiography: 

—An ECG should be taken and the patient should be put on a continuous heart monitor.

—Peaked T waves and a shorter QT interval are early ECG abnormalities.

—Later, enlarged QRS complexes, protracted PR intervals, small P waves, and elevation or depression of the ST segment are observed. 

—In addition to a sine wave pattern, ventricular fibrillation, and asystole, advanced modifications include absent P waves, distinct QRS complex enlargement, and tall T waves.

THERAPY

1.Acute therapy:

a)Calcium chloride or calcium gluconate is administered over 2 minutes and repeated in 5 to 10 minutes if necessary. Calcium is the most crucial first step in treatment because it prevents malignant arrhythmia by stabilising cell membranes without affecting potassium levels. Calcium chloride should ideally be administered through a central line since if it accidentally leaks from peripheral intravenous lines, it severely damages skin.

b) Sodium bicarbonate (44 mEq [one ampule] administered intravenously over 5 minutes and repeated 10 to 15 minutes later if necessary) causes an intracellular influx of potassium. Onset of action occurs in approximately 15 minutes.

c) Regular insulin (10 to 20 U administered via an intravenous push) with 10% dextrose (500 mL in water) administered over 1 hour, or 10U of insulin administered via an intravenous push with one or two ampules (25 g) of 50% glucose administered over 5 minutes will lower potassium by causing an intracellular shift. Effects occur 30 to 60 minutes after administration.

d)Furosemide, bumetanide, and acetazolamide all increase potassium excretion.

e) Dialysis should be considered for patients with severe hyperkalemia who have failed to respond to pharmacologic attempts at lowering the potassium level and for patients with acute or chronic renal failure.

2. Maintenance of potassium balance. Potassium balance is maintained by:

a) Diuretics and fludrocortisone

b) Cation-exchange resins, such as sodium polystyrene sulfonate

c) Aldosterone, either as desoxycorticosterone acetate or fludrocortisone acetate.

DISPOSITION

Admission: When ECG abnormalities or clinical manifestations of hyperkalemia are present, admission to the intensive care unit with continuous cardiac monitoring is required.

Discharge: Patients with mild serum potassium elevations in the absence of clinical and ECG abnormalities can be discharged, provided any identifiable predisposing factors have been corrected. Patients should have a follow-up evaluation within 48 to 72 hours.