Transient hyperphosphatasemia in a toddler with COVID-19 infection: A case report and literature review.

Background: Transient hyperphosphatasemia (TH) is a condition characterized by elevated serum alkaline phosphatase (ALP) in the clinical setting with no evidence of bone or liver disease among children under the age of 5. Typically, it will resolve spontaneously in a few months in the majority of cases. TH has been found to be associated with viral infections. Two cases of TH associated with coronavirus disease 2019 (COVID-19) infection in toddlers have been previously reported.

Case summary: A previously healthy 2-year-old boy presented with fever and positive real-time polymerase chain reaction for COVID-19. Prior to his illness, the patient had been in close contact with his grandfather, who later developed COVID-19. The physical examination on admission was unremarkable. He remained asymptomatic throughout 7 d of hospitalization. On the 5^th day of his illness, blood tests showed markedly elevated serum ALP (4178 U/L). Results from the simultaneous testing of the remaining liver profiles and metabolic bone panels were normal. Two months after discharge from the hospital, the patient continued to thrive well. The skeletal surveys revealed no significant abnormalities. The serum ALP declined into the normal range adjusted for his age. This evidence is consistent with the diagnosis of TH.

Conclusion: TH can occur in COVID-19-infected toddlers. Serial measurements of ALP levels have been shown to gradually decline into the normal range within a few months. Therefore, being aware of this transient abnormality will help clinicians to avoid additional unnecessary investigations.