A case of transient hyperphosphatasemia presenting with mild degree of bow legs

Introduction: Transient Hyperphosphatasia (TH) is a benign condition in which serum Alkaline Phosphatase is elevated without any underlying pathology. This is mainly seen in children compared to adults and it is usually an incidental finding. The hallmark of the condition is that normalization of ALP level will with time. However, not knowing the entity would lead to unnecessary investigations and referrals. Here we report a child with TH who presents with a mild degree of bow legs.

Case report: A 1year and 8 months old boy was brought by his mother with a concern of bow legs. He was the first child born to non-consanguineous healthy parents following normal antenatal and perinatal periods. His birth weight was 3.5kg and he was growing in his birth centile. He had age-appropriate development and parents had been having a concern about bow legs after he started walking. He is getting an average Sri Lankan diet with animal food and he gets adequate sun exposure as well. There was no history to suggest the liver of renal diseases.

On examination, he had a mild degree of bow legs without any features to suggest rickets. His cardiovascular, respiratory, abdominal, and neurology exams were normal.

His bone profile showed a high value of ALP (3782 U/L) with normal calcium, phosphate, and vitamin D levels. Due to high ALP levels, he underwent liver and renal functions and that was within the normal range.

The diagnosis was made as TH and he was followed up monthly with ALP values. He had a downward trend of ALP levels and in 3 months the ALP value dropped to (580 U/L). Parents were reassured about the condition and the diagnosis was confirmed as TH.

Conclusion: It is important to rule out, bone, kidney, or a liver pathology if a child has markedly elevated ALP levels. However, it is important to recognize this entity to avoid unnecessary procedures and concerns.