Yes, Elevated Alkaline Phosphatase is Normal in Pediatric Patients
Alkaline phosphatase (ALP) levels are physiologically elevated throughout childhood and adolescence compared to adults, and this elevation is completely normal due to active skeletal growth and bone development. 1
Why Pediatric ALP is Naturally Elevated
- Bone-specific ALP represents 80-90% of total ALP in children's serum, compared to only 50% in adults, making higher baseline levels expected and normal 1, 2
- The elevation reflects active skeletal development and bone growth, which is a continuous process throughout childhood and peaks during adolescence 1
- You must use age-specific pediatric reference ranges when interpreting ALP levels—never use adult reference ranges, as this is a critical pitfall that leads to unnecessary workup 1
When Elevated ALP Requires Investigation
While physiologic elevation is normal, you need to distinguish this from pathologic causes:
Step 1: Compare to Age-Specific Reference Ranges
- First determine if the elevation exceeds age-appropriate pediatric norms (not adult norms) 1
- If within age-specific range, no further workup is needed
Step 2: Measure GGT to Identify the Source
- Obtain gamma-glutamyl transpeptidase (GGT) to differentiate hepatic from bone sources—this is the critical first test 1, 2
- Normal GGT with elevated ALP indicates bone source (likely physiologic) 1
- Elevated GGT with elevated ALP confirms hepatic origin and indicates cholestasis requiring further evaluation 1
Step 3: If GGT is Normal (Bone Source)
- Check serum phosphate, calcium, parathyroid hormone (PTH), and 25-hydroxyvitamin D levels 1
- Low phosphate with elevated ALP suggests rickets or X-linked hypophosphatemia 1
- Consider benign transient hyperphosphatasemia, which occurs in otherwise healthy infants and children (median age 14 months), often after recent fever, gastroenteritis, or viral infection, with ALP levels sometimes exceeding 1000 U/L that resolve spontaneously within months 3, 4
Common Clinical Pitfalls to Avoid
- Do not assume all elevated ALP in children is physiologic without checking GGT first 1
- Do not use adult reference ranges—this is the most common error leading to unnecessary anxiety and testing 1
- Do not immediately pursue extensive workup if the child is otherwise healthy with normal GGT; consider benign transient hyperphosphatasemia and repeat ALP in 2-4 months 3, 4
- Remember that healing fractures can also elevate ALP, which may be relevant in trauma or abuse evaluations 1
The "Wait and See" Approach
When benign transient hyperphosphatasemia is suspected in an otherwise healthy child with no clinical or laboratory evidence of bone or liver disease, a "wait and see" approach with repeat ALP testing in a few months is optimal to avoid unnecessary investigations and parental anxiety 3, 4