Introduction: Pediatric dose calculations by body surface area (BSA) are vital for B. Pharm students to ensure safe, effective therapy. BSA-based dosing aligns drug exposure with physiologic factors such as cardiac output, hepatic clearance, glomerular filtration, and metabolic rate. You will use the Mosteller formula [BSA = sqrt((height in cm × weight in kg)/3600)] and Du Bois equation, scale adult doses by (BSA/1.73), and compute mg/m2 regimens common in oncology and other narrow therapeutic index drugs. Mastery requires precise units (cm, kg, m2), appropriate rounding, respecting adult maximum doses, and special-population considerations (neonates, obesity). These skills reduce medication errors and optimize pediatric pharmacotherapy. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Why is BSA-based dosing used in pediatrics?
- It correlates better with physiologic determinants of drug clearance than weight alone.
- It is simpler to perform than mg/kg dosing.
- It eliminates the need for clinical monitoring.
- It guarantees identical exposure across all pediatric ages.
Correct Answer: It correlates better with physiologic determinants of drug clearance than weight alone.
Q2. Which is the correct Mosteller formula for BSA?
- BSA (m2) = sqrt([height(cm) × weight(kg)]/3600)
- BSA (m2) = sqrt([height(m) × weight(kg)]/360)
- BSA (m2) = [height(cm) + weight(kg)]/3600
- BSA (m2) = 0.1 × height(m) × weight(kg)
Correct Answer: BSA (m2) = sqrt([height(cm) × weight(kg)]/3600)
Q3. What is the correct unit for body surface area?
- Square meters (m2)
- Kilograms (kg)
- Liters (L)
- Milligrams (mg)
Correct Answer: Square meters (m2)
Q4. What standard adult BSA value is commonly used for dose scaling?
- 1.73 m2
- 1.00 m2
- 2.00 m2
- 1.50 m2
Correct Answer: 1.73 m2
Q5. Which is the correct Du Bois formula?
- BSA (m2) = 0.007184 × weight(kg)0.425 × height(cm)0.725
- BSA (m2) = 0.007184 × weight(kg)0.725 × height(cm)0.425
- BSA (m2) = 0.007184 × weight(kg)1 × height(cm)1
- BSA (m2) = 0.017184 × weight(kg)0.425 × height(cm)0.725
Correct Answer: BSA (m2) = 0.007184 × weight(kg)0.425 × height(cm)0.725
Q6. In which scenario is BSA-based dosing most appropriate?
- For cytotoxic chemotherapy and drugs with narrow therapeutic index requiring exposure matching
- For oral rehydration salts
- For routine antibiotics in term neonates
- For single-dose vitamin D supplementation
Correct Answer: For cytotoxic chemotherapy and drugs with narrow therapeutic index requiring exposure matching
Q7. Calculate BSA by Mosteller for a child 100 cm tall and 15 kg.
- 0.65 m2
- 0.55 m2
- 0.75 m2
- 0.95 m2
Correct Answer: 0.65 m2
Q8. If adult dose = 400 mg and child’s BSA = 0.65 m², scaled pediatric dose is approximately:
- 150 mg
- 200 mg
- 250 mg
- 300 mg
Correct Answer: 150 mg
Q9. Order: 250 mg/m². Child’s BSA = 0.78 m². What is the dose?
- 195 mg
- 180 mg
- 200 mg
- 220 mg
Correct Answer: 195 mg
Q10. What happens if height in meters is mistakenly used in the Mosteller formula instead of centimeters?
- Severely underestimates BSA and dose
- Has no effect because units cancel out
- Overestimates BSA by ~100×
- Only affects patients taller than 1 m
Correct Answer: Severely underestimates BSA and dose
Q11. Which dosing basis is standard for pediatric oncology protocols?
- mg/m² based on BSA
- mg/kg based on weight alone
- Fixed adult dose scaled by age
- Dose based on body mass index (BMI)
Correct Answer: mg/m² based on BSA
Q12. For preterm neonates, which approach is generally preferred?
- mg/kg with maturation-based adjustments
- mg/m² BSA-based dosing
- Fixed fraction of adult dose
- Dose based on chronological age only
Correct Answer: mg/kg with maturation-based adjustments
Q13. How should BSA typically be reported in practice?
- Report to two decimal places (e.g., 0.78 m²)
- Report to three significant figures
- Report as an integer percentage of 1.73
- No rounding; record full calculator output
Correct Answer: Report to two decimal places (e.g., 0.78 m²)
Q14. How should obesity be handled in pediatric BSA dosing?
- Use actual weight for Mosteller, consider dose caps not exceeding adult maximums when appropriate
- Use ideal body weight for all drugs by default
- Always reduce calculated mg/m² dose by 20% in obesity
- Switch to mg/kg dosing automatically
Correct Answer: Use actual weight for Mosteller, consider dose caps not exceeding adult maximums when appropriate
Q15. Calculated dose is 205 mg; only 200 mg scored tablets are available. What is best practice?
- Dispense 200 mg (within 10% rounding), document and monitor
- Dispense 210 mg to avoid underdosing
- Split multiple tablets to make exactly 205 mg regardless of formulation stability
- Cancel the dose; BSA dosing cannot be rounded
Correct Answer: Dispense 200 mg (within 10% rounding), document and monitor
Q16. Calculate BSA for height 90 cm and weight 12 kg (Mosteller).
- 0.55 m²
- 0.45 m²
- 0.65 m²
- 0.75 m²
Correct Answer: 0.55 m²
Q17. Order: 150 mg/m². BSA = 0.55 m². Dose?
- 82.5 mg
- 75 mg
- 90 mg
- 100 mg
Correct Answer: 82.5 mg
Q18. Calculate BSA for height 130 cm and weight 30 kg (Mosteller).
- 1.04 m²
- 0.94 m²
- 1.14 m²
- 0.84 m²
Correct Answer: 1.04 m²
Q19. A drug is ordered at 50 mg/m² for a child with BSA 1.04 m². Dose?
- 52 mg
- 50 mg
- 55 mg
- 60 mg
Correct Answer: 52 mg
Q20. Adult dose is 1,000 mg. Child BSA = 1.04 m². Scaled pediatric dose is approximately:
- 600 mg
- 520 mg
- 700 mg
- 400 mg
Correct Answer: 600 mg
Q21. What is a safe verification step after calculating a BSA-based dose?
- Independently recalculate (manual or second tool), verify units, and document result
- Trust the EHR calculator without verification
- Ask the caregiver to confirm the math
- Skip verification for non-chemotherapy drugs
Correct Answer: Independently recalculate (manual or second tool), verify units, and document result
Q22. How is a BSA nomogram typically used?
- Draw a straight line connecting height and weight and read BSA at the intersection
- Connect height to age and read weight, then compute BSA
- Trace the 50th percentile growth curve to estimate BSA
- Use height only; weight is unnecessary
Correct Answer: Draw a straight line connecting height and weight and read BSA at the intersection
Q23. Which physiologic parameters support the rationale for BSA-based dosing?
- Cardiac output, glomerular filtration, and hepatic blood flow correlate with BSA
- Only body fat correlates with BSA
- BSA correlates solely with age
- BSA is unrelated to pharmacokinetics
Correct Answer: Cardiac output, glomerular filtration, and hepatic blood flow correlate with BSA
Q24. Which statement best reflects safe practice regarding adult maximum doses?
- Never exceed the recommended adult maximum dose, even if mg/m² suggests more
- Exceed adult max if BSA is ≥1.73 m²
- Average with mg/kg to justify higher doses
- Cap only chemotherapy, not other drugs
Correct Answer: Never exceed the recommended adult maximum dose, even if mg/m² suggests more
Q25. Calculate BSA for height 80 cm and weight 10 kg (Mosteller).
- 0.47 m²
- 0.40 m²
- 0.57 m²
- 0.67 m²
Correct Answer: 0.47 m²
Q26. Adult dose = 750 mg. Child BSA = 0.47 m². Scaled pediatric dose (nearest 5 mg)?
- 205 mg
- 180 mg
- 250 mg
- 300 mg
Correct Answer: 205 mg
Q27. What is “dose banding” in BSA-based dosing?
- Group doses into predefined bands by BSA to standardize and reduce compounding variability
- Always round to the nearest 50 mg regardless of drug
- Convert all mg/m² to mg/kg equivalents
- Use adult bands for all pediatric patients
Correct Answer: Group doses into predefined bands by BSA to standardize and reduce compounding variability
Q28. Which child has the larger BSA (Mosteller, approximate)?
- Child A: 110 cm, 20 kg
- Child B: 100 cm, 25 kg
- Both equal
- Cannot be compared without BMI
Correct Answer: Child B: 100 cm, 25 kg
Q29. In the Mosteller formula, what is the denominator constant?
- 3600
- 36
- 173
- 360
Correct Answer: 3600
Q30. Height 140 cm, weight 40 kg (BSA ≈ 1.25 m²). Order: 75 mg/m². Adult maximum per dose is 90 mg. Final prescribed dose?
- 90 mg
- 93.75 mg
- 100 mg
- 80 mg
Correct Answer: 90 mg
