What diagnosis (and ICD‑10 code) should be documented when prescribing a WIC‑approved infant formula for a constipated child?

WIC Formula Prescription for Infant Constipation

For WIC formula coverage in a constipated infant, document "Functional Constipation" with ICD-10 code K59.00 (Constipation, unspecified) or K59.09 (Other constipation). This diagnosis qualifies as a medical condition requiring specialized formula under WIC guidelines when standard formula modifications are insufficient.

When to Consider Formula Change for WIC Coverage

Before prescribing a specialized formula, rule out cow's milk protein intolerance, which can manifest as constipation and is frequently missed. 1

• A 2- to 4-week trial of an extensively hydrolyzed or amino acid-based formula is recommended when cow's milk protein intolerance is suspected in formula-fed infants with persistent constipation 1
• Evidence shows that 24% of formula-fed infants with gastrointestinal symptoms (including constipation) resolved after switching to a protein-hydrolysate formula 1
• This diagnostic trial approach is supported by pediatric gastroenterology guidelines 1

Specialized Formulas That May Qualify for WIC

For true functional constipation without milk protein allergy, formulas enriched with high β-palmitate and increased magnesium content may be considered to soften stool. 2

• These formulas work by altering fat absorption and increasing intestinal water content 2
• The ESPGHAN Nutrition Committee recognizes these formulas as potentially beneficial for constipation management 2
• However, evidence supporting specialized formulas for functional gastrointestinal disorders remains limited 2

First-Line Management Before Formula Change

Fruit juices containing sorbitol (prune, pear, apple) are recommended as first-line treatment before changing formula. 1

• The North American Society of Pediatric Gastroenterology specifically recommends these juices due to their poorly absorbed sorbitol creating an osmotic load 1
• Start with small amounts (10 mL/kg body weight) to increase stool water content 1
• Avoid excessive juice consumption as it may lead to diarrhea and poor weight gain 1

Documentation Requirements for WIC

Your prescription must clearly state:

• Primary diagnosis: Functional Constipation (K59.00 or K59.09)
• Secondary diagnosis if applicable: Cow's milk protein intolerance (K52.82) if trial indicates this etiology
• Specific formula name and reason standard formula is inadequate
• Duration of prescription (typically 3-6 months with reassessment)

Critical Pitfalls to Avoid

• Do not dilute formula – this compromises nutrition and does not help constipation 1
• Do not discontinue breastfeeding in favor of specialized formula; breastfed infants with constipation should continue nursing 1, 2
• Do not assume normal stool pH or reducing substances rule out problems – clinical symptoms are more important than isolated lab findings 1
• Ensure adequate hydration while maintaining full-strength formula 1

When Specialized Formula Is NOT Indicated

• Breastfed infants experiencing constipation should not transition to commercial formulas 2
• Reassure parents that functional constipation is typically normal and does not necessitate formula change in most cases 2
• Only 5-10% of childhood constipation has an organic cause requiring specialized intervention 3

Follow-Up and Reassessment

• Monitor for warning signs: vomiting (especially bilious), poor weight gain, or failure to respond to treatment 1
• If constipation persists despite formula change and dietary interventions, consider referral to pediatric gastroenterology 3
• Long-term improvement occurs in only 50-70% of children with functional constipation despite treatment 4