Weight < 3rd percentile, weight crossing > 2 major percentiles down, or weight-for-length < 80% expected. ED's role is to identify dehydration, severe malnutrition, abuse/neglect, and acute organic causes — most workup is outpatient.
🚩 Red-flag clues (must not miss)
- •Severe wasting (Z-score < −3) — risk of refeeding syndrome
- •Bruises in non-ambulatory infant + FTT = NAT / neglect
- •FTT + chronic diarrhea + edema = celiac, CF, protein-losing enteropathy
- •FTT + recurrent infections = immunodeficiency / HIV
History
- Detailed feeding diary, formula prep (correct dilution?), breastfeeding
- Birth weight, prenatal exposure, prematurity
- Stool, vomiting, fatigue with feeds
- Psychosocial: caregiver mental health, food insecurity
Exam
- Weight, length, HC plotted; weight-for-length
- Subcutaneous fat (cheeks, buttocks), muscle wasting (temporals)
- Dysmorphic features (genetic), hepatosplenomegaly
- Skin: bruising, hygiene
Labs
- CBC, BMP, Mg, Phos, LFTs, albumin, prealbumin
- TSH, celiac panel, sweat chloride if indicated
- Stool: fat, elastase, ova/parasites
- HIV in at-risk
Differential & next step
| Diagnosis | Clue | Next step |
|---|---|---|
| Inadequate intake (most common) | Improper formula prep, poor latch | Lactation, feeding plan, social work |
| Neglect / abuse | Bruises, hygiene, weight gain in hospital | Admit, social work, mandatory report |
| GERD severe | Vomiting with feeds, irritable | Trial PPI; pH probe outpatient |
| Cow milk protein allergy | Blood-streaked stool, eczema | Hydrolyzed formula |
| Cystic fibrosis | Salty sweat, recurrent pulm infx, steatorrhea | Sweat chloride |
| Celiac disease | Diarrhea after gluten, distention | TTG IgA |
| Hyperthyroidism | Tachycardia, weight loss, ↑ appetite | TSH, free T4 |
| Cardiac (CHF) | Sweating with feeds, hepatomegaly | Echo |
| Renal (RTA) | Polyuria, alkali wasting | BMP, urine pH |
| HIV / immunodeficiency | Recurrent OIs, oral thrush > 6 mo | HIV PCR, immune w/u |
Management / next steps
- Admit if severe (< 70% IBW), dehydrated, suspected NAT, or failed outpatient
- Initiate refeeding cautiously (start ~80% caloric needs, advance over days) — monitor PO₄, K, Mg q12h
- Multidisciplinary: nutrition, social work, lactation, GI
Source: https://fprmed.com/fprmedcom/Pages/Pedi/FTT.html
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