Failure to thrive and faltering growth: diagnostic approach — formative SAQs

SAQ 1 (10)

A 5-month-old breastfed infant has fallen from the 50th to the 9th weight centile over 8 weeks. Length is tracking the 25th centile. The infant feeds for 45 minutes each side, has three wet nappies daily, and looks thin but interactive. Examination is otherwise normal. ^{[1] [3]}

1. Define the problem representation and explain why a single low centile is not enough. (3) ^{[1] [6]}
2. List the four mechanism buckets and state the most likely primary mechanism here. (3) ^[1]
3. Outline your immediate assessment steps and first-line management plan, including follow-up. (4) ^{[1] [2] [3]}

Model answer

Problem representation. Serial weights show falling velocity after prior higher tracking — faltering growth / FTT pattern, not a final organ diagnosis. Definitions vary; velocity and pattern matter more than one percentile alone. ^{[1] [6]}

Mechanisms. Inadequate intake; increased losses; increased needs; ineffective utilisation. Most likely primary mechanism: inadequate milk transfer/intake (long feeds, few wet nappies, weight falling faster than length). ^{[1] [3]}

Plan. Re-measure and re-plot; assess stability; observe a feed; lactation support; ensure adequate intake (supplementation plan if needed, intentional and reviewed); directed tests only if red flags; early weight review (days–2 weeks); safety-net fewer wet nappies, lethargy, vomiting. ^{[1] [2]}