Serum electrolytes and management of their imbalances

Serum Electrolytes: Normal Ranges, Functions, Imbalances and Management

Normal Ranges

• Sodium: 135–145 mEq/L
• Potassium: 3.5–5.0 mEq/L
• Chloride: 98–106 mEq/L
• Bicarbonate: 22–28 mEq/L

• Calcium (total): 8.5–10.5 mg/dL
• Magnesium: 1.7–2.4 mg/dL
• Phosphate: 2.5–4.5 mg/dL

Functions

• Sodium regulates extracellular volume and osmolality.
• Potassium maintains membrane potential and cardiac rhythm.
• Chloride helps maintain acid base balance.
• Bicarbonate buffers metabolic acids.
• Calcium supports muscle contraction and coagulation.
• Magnesium stabilizes cardiac conduction and ATP reactions.
• Phosphate supports ATP, bone mineralization and cell energy transfer.

Imbalances, Signs and Causes

Hyponatremia

• Causes: SIADH, diuretics, heart failure, excess hypotonic fluids.
• Signs: nausea, confusion, seizure.

Hypernatremia

• Causes: water loss, diabetes insipidus, impaired thirst.
• Signs: irritability, lethargy, seizures.

Hypokalemia

• Causes: diuretics, vomiting, insulin, alkalosis.
• Signs: weakness, cramps, constipation, arrhythmias.

Hyperkalemia

• Causes: renal failure, ACE inhibitors, potassium sparing drugs.
• Signs: paresthesia, weakness, peaked T waves to sine wave.

Hypocalcemia

• Causes: vitamin D deficiency, CKD, hypoparathyroidism.
• Signs: tetany, perioral numbness, Chvostek or Trousseau.

Hypercalcemia

• Causes: hyperparathyroidism, malignancy.
• Signs: polyuria, confusion, abdominal pain, short QT.

Hypomagnesemia

• Causes: diarrhea, diuretics, alcohol.
• Signs: tremor, arrhythmias, refractory hypokalemia.

Hypermagnesemia

• Causes: excess supplementation, renal failure.
• Signs: hypotension, hyporeflexia.

Hypophosphatemia

• Causes: refeeding, alcohol misuse, DKA correction.
• Signs: weakness, respiratory failure, hemolysis.

Hyperphosphatemia

• Causes: renal failure, tumor lysis.
• Signs: often asymptomatic, may trigger hypocalcemia symptoms.

Management

Hyponatremia

• Fluid restriction for dilutional causes.
• Isotonic saline for hypovolemia.
• Hypertonic saline for seizures with close monitoring.

Hypernatremia

• Oral water if tolerated.
• Hypotonic IV fluids with slow correction.

Hypokalemia

• Oral potassium for mild cases.
• IV potassium with monitoring for severe cases.
• Correct magnesium first if low.

Hyperkalemia

• IV calcium to stabilize myocardium.
• Insulin with glucose plus beta agonists to shift K intracellularly.
• Diuretics, binders or dialysis to remove K.

Hypocalcemia

• IV calcium gluconate for symptomatic cases.
• Oral calcium and vitamin D for chronic causes.

Hypercalcemia

• IV saline hydration.
• Bisphosphonates or denosumab for malignancy.
• Calcitonin for rapid short-term lowering.

Magnesium Disorders

• Low: oral or IV magnesium.
• High: stop magnesium, give IV fluids and consider dialysis.

Phosphate Disorders

• Low: oral phosphate or IV for severe cases.
• High: dietary restriction, binders and treat renal failure.

Author: Dr. Sunil Paul

Serum Electrolytes, Know What They Mean