Why would a patient with leukocytosis and thrombocytosis be given D5NS (5% dextrose in normal saline)?

D5NS Administration in Leukocytosis and Thrombocytosis

A patient with leukocytosis and thrombocytosis would receive D5NS (5% dextrose in normal saline) primarily for hydration to prevent tumor lysis syndrome, maintain adequate renal perfusion, and reduce blood viscosity—not to directly treat the elevated cell counts themselves. 1

Primary Indication: Tumor Lysis Syndrome Prevention

Vigorous hydration is the cornerstone of prophylaxis for patients at risk of tumor lysis syndrome, which commonly occurs in hematologic malignancies presenting with elevated white blood cell and platelet counts. 1

• Pediatric patients should receive 2-3 L/m²/day IV of one-quarter normal saline with 5% dextrose, maintaining urine output at 80-100 mL/m²/h 1
• The dextrose component prevents hypoglycemia during aggressive hydration and provides metabolic support 1
• Potassium, calcium, and phosphate should be withheld initially from hydration fluids due to concurrent risks of hyperkalemia and hyperphosphatemia 1

Viscosity Reduction in Hyperleukocytosis

In patients with hyperleukocytosis (WBC >100 × 10⁹/L) combined with thrombocytosis, aggressive hydration with D5NS reduces blood viscosity and decreases the risk of CNS hemorrhage and thrombotic complications. 2

• The combination of thrombocytopenia and hyperleukocytosis creates a "critical period" with disproportionately high mortality risk from CNS hemorrhage 2
• Hydration helps maintain renal perfusion and prevents acute kidney injury from leukostasis 1
• Packed red blood cells should be avoided during hyperleukocytosis as they further increase blood viscosity 2

Metabolic Support During Treatment

The dextrose component serves specific metabolic functions beyond simple caloric support:

• Prevents hypoglycemia, which is a complicating factor and risk factor for fatal outcomes in critically ill hematologic patients 1
• Provides substrate during periods of decreased oral intake 1
• The half-normal saline component (when D5 1/2NS is used) provides less sodium to prevent fluid overload while maintaining intravascular volume 1

Thrombotic Risk Considerations

Paradoxically, extreme thrombocytosis (>1000 × 10⁹/L) is associated with lower thrombotic risk, while the combination of moderate thrombocytosis with leukocytosis significantly increases thrombotic complications. 3

• Leukocytosis is a stronger independent risk factor for thrombosis than platelet count in essential thrombocythemia 3, 4
• The highest thrombotic risk occurs with leukocytosis combined with platelet counts below 1000 × 10⁹/L 3
• Adequate hydration helps prevent thrombotic complications by maintaining blood flow and reducing stasis 1

Critical Pitfalls to Avoid

• Do not use alkalinized fluids (sodium bicarbonate) routinely, as this increases calcium phosphate precipitation risk without proven benefit 1
• Avoid fluid overload, which can precipitate pulmonary edema or ARDS and worsen cerebral edema 1
• Monitor urine-specific gravity and maintain at 1.010 to ensure adequate hydration 1
• Do not transfuse packed red blood cells during hyperleukocytosis with thrombocytosis, as this dangerously increases blood viscosity 2