What are the laboratory electrolyte levels?

From the Guidelines

Laboratory electrolyte testing is crucial for assessing a patient's fluid and electrolyte balance, and a standard electrolyte panel should include sodium, potassium, chloride, and bicarbonate (CO2) levels, with normal ranges approximately being: sodium 135-145 mEq/L, potassium 3.5-5.0 mEq/L, chloride 96-106 mEq/L, and bicarbonate 22-29 mEq/L 1. When evaluating patients with dehydration, kidney disease, heart failure, vomiting, diarrhea, or those taking medications that affect electrolyte levels, such as diuretics or ACE inhibitors, these tests should be ordered. Abnormal results require clinical correlation and may necessitate treatment, for example:

• Hypokalemia (low potassium) might require oral supplementation with potassium chloride 20-40 mEq daily
• Severe hyperkalemia may need emergency intervention with calcium gluconate, insulin with glucose, or sodium polystyrene sulfonate. Electrolyte imbalances can cause serious complications, including:
• Cardiac arrhythmias
• Muscle weakness
• Seizures
• Altered mental status Regular monitoring is particularly important in:
• Hospitalized patients
• Those with chronic conditions affecting fluid balance
• Patients on medications that alter electrolyte levels Electrolyte homeostasis is maintained primarily by the kidneys, which regulate excretion and reabsorption in response to hormonal signals like aldosterone and antidiuretic hormone 1. The most recent and highest quality study 1 emphasizes the importance of monitoring and managing hyperkalemia, especially in patients with cardiovascular disease, chronic kidney disease, and those taking renin-angiotensin-aldosterone system inhibitors. Key points to consider when managing electrolyte imbalances include:
• The severity of hyperkalemia can be classified as mild, moderate, or severe, with thresholds of >5.0 to <5.5 mEq/L, 5.5 to 6.0 mEq/L, and >6.0 mEq/L, respectively 1
• The risk of arrhythmic emergencies and sudden arrhythmic death varies widely among patients with hyperkalemia, and life-threatening arrhythmias may occur at different thresholds 1.

From the FDA Drug Label

Plasma electrolyte concentrations should be closely monitored in the pediatric population as this population may have impaired ability to regulate fluids and electrolytes.

The monitoring of lab electrolytes is necessary, especially in the pediatric population, due to their potential impaired ability to regulate fluids and electrolytes 2.

From the Research

Lab Electrolytes

• Lab electrolytes are crucial in diagnosing and managing various electrolyte disorders, including hypokalemia and hyperkalemia 3, 4.
• Hypokalemia is characterized by serum potassium levels less than 3.5 mEq per L, while hyperkalemia is characterized by serum potassium levels greater than 5.0 mEq per L 4.
• Causes of hypokalemia include decreased intake, renal losses, gastrointestinal losses, or transcellular shifts, whereas causes of hyperkalemia include impaired renal excretion, transcellular shifts, or increased potassium intake 3, 4.

Diagnosis and Management

• Diagnosis of electrolyte disorders involves a combination of history, physical examination, laboratory findings, and electrocardiography 3, 5.
• Treatment of hypokalemia involves replenishing potassium levels, preferably through an oral route if the patient has a functioning gastrointestinal tract and a serum potassium level greater than 2.5 mEq per L 4.
• Treatment of hyperkalemia may include intravenous calcium, insulin, sodium bicarbonate, diuretics, and beta agonists, as well as dialysis in severe cases 4.

Monitoring and Assessment

• Monitoring and assessment of fluid and electrolyte balances are crucial in patient care, and involve key parameters such as hydration status, acid-base status, plasma and urine osmolality, and electrolyte levels 5, 6.
• Understanding the pathophysiology of electrolyte disorders is essential for initiating appropriate therapy and preventing further complications 5.