What is the recommended initial dose of Lasix (furosemide) for a 4-year-old patient weighing 10 kg with potential impaired renal function?

Furosemide Dosing for a 4-Year-Old Child Weighing 10 kg

For a 4-year-old weighing 10 kg, administer furosemide 10 mg IV/IM as the initial dose (1 mg/kg), given slowly over 1-2 minutes. 1

Initial Dose Calculation

• The FDA-approved initial pediatric dose is 1 mg/kg body weight, administered slowly under close medical supervision. 1
• For this 10 kg child, the calculation is straightforward: 1 mg/kg × 10 kg = 10 mg IV or IM 1
• The injection must be given slowly (over 1-2 minutes for IV administration) to minimize adverse effects 1

Dose Escalation if Needed

• If the diuretic response to the initial 10 mg dose is inadequate, increase by 1 mg/kg (10 mg for this child) no sooner than 2 hours after the previous dose 1
• Continue this stepwise escalation until achieving the desired diuretic effect 1
• The absolute maximum dose is 6 mg/kg body weight (60 mg for this 10 kg child), which should not be exceeded 1

Critical Monitoring Requirements

• Place a bladder catheter or monitor urine output closely to assess treatment response rapidly 2
• Monitor for signs of hypovolemia: decreased skin turgor, hypotension, tachycardia 2
• Check electrolytes (particularly potassium and sodium) within 6-24 hours after administration 3
• Assess renal function and blood pressure regularly during therapy 3

Special Considerations for Renal Impairment

• If this child has impaired renal function (creatinine clearance <30 mL/min), reduce the dosing frequency to once daily rather than reducing the individual dose 2
• The mg/kg dose should be maintained to take advantage of concentration-dependent effects 2
• In renal insufficiency, monitor serum drug concentrations if available to avoid toxicity 2

Common Pitfalls to Avoid

• Never administer furosemide if the child has marked hypovolemia, severe hyponatremia, or anuria—these are absolute contraindications 2, 3
• Do not give furosemide if systolic blood pressure is inadequate (<90 mmHg equivalent for age) without circulatory support, as it will worsen hypoperfusion 3
• Avoid rapid IV push—always administer over 1-2 minutes to prevent ototoxicity 1
• Do not exceed 6 mg/kg/day total dose in pediatric patients, as higher doses are not recommended and increase toxicity risk 1
• Infusions should be administered over 5-30 minutes when using higher doses to avoid hearing loss 3

Route Selection

• IV route is preferred in acute situations requiring rapid diuresis (pulmonary edema, severe fluid overload) 3
• IM route is acceptable if IV access is difficult, though onset may be slightly delayed 1
• Oral administration should replace parenteral therapy as soon as the clinical situation permits 1

Concurrent Therapy Considerations

• The risk of ototoxicity increases significantly when furosemide is used concurrently with aminoglycosides (streptomycin, amikacin, kanamycin) 2
• If aminoglycosides are being administered, use furosemide with extreme caution and monitor hearing function 2
• Ensure adequate potassium supplementation or consider potassium-sparing diuretics if prolonged therapy is anticipated 4