Transient Hyperphosphatasemia in a Child with Autism Spectrum Disorder

Area of Science:

• Pediatric Medicine
• Biochemistry
• Neurodevelopmental Disorders

Background:

• Autism spectrum disorder (ASD) is a neurodevelopmental condition affecting social communication and behavior.
• Transient hyperphosphatasemia of infancy and early childhood (THI) is a benign disorder marked by temporary, extremely high serum alkaline phosphatase (S-ALP) levels.

Observation:

• A 21-month-old girl presented with a leg limp and psychomotor developmental delay.
• Her serum alkaline phosphatase (S-ALP) was significantly elevated (61.74 μkat/L), meeting criteria for THI after other causes were excluded.
• Neurologic and developmental assessments confirmed a diagnosis of autism spectrum disorder (ASD).

Findings:

• The elevated S-ALP normalized within 3 months, confirming THI.
• No causal link was found between THI and ASD; the high S-ALP was an incidental laboratory finding.
• This case highlights the importance of recognizing THI as a benign, transient condition.

Implications:

• THI in children, especially those with new or existing conditions, can cause physician concern.
• Extensive investigations and blood draws for children diagnosed with THI are often unnecessary.
• Accurate diagnosis of THI prevents unnecessary medical interventions and anxiety for families.