ESPE Abstracts

Objective: Elevated serum alkaline phosphatase (ALP) levels in pediatric patients can result from various etiologies, with transient hyperphosphatasemia, bone pathologies, and hepatic diseases being the most common. This study aimed to elucidate the etiological factors responsible for elevated ALP levels and to evaluate the clinical presentations of transient hyperphosphatasemia in these patients.

Materials and Methods: This retrospective study included 275 children who presented to our tertiary hospital over the past five years with serum alkaline phosphatase (ALP) levels ≥500 IU/L. Clinical, biochemical, and radiological data were collected from hospital records. Children were diagnosed as transient hyperphosphatasemia if they exhibited no specific historical features, had normal physical examination findings, and displayed normal laboratory tests aside from elevated ALP (including liver and kidney function tests, calcium, phosphorus, vitamin D, and parathyroid hormone levels), with ALP levels returning to normal upon follow-up. Data were presented as percentages, numbers, medians, and interquartile ranges (25th-75th percentiles).

Results: A total of 275 patients were included in the study. Among the patients, 62.2% (n = 171) were diagnosed with transient hyperphosphatasemia, 8.7% (n = 24) with rickets, and 29.1% (n = 80) with other diseases, including gastrointestinal diseases, kidney diseases, malignant diseases, and metabolic bone disease of prematurity. In the transient hyperphosphatasemia group, 64.3% (n = 110) were male, with a median age of 1.6 years (range: 0.3-4.6) and a median ALP value of 649 IU/L (range: 546-1033). In the rickets group, 45.8% (n = 11) were male, with a median age of 1.9 years (range: 1.2-8.7) and a median ALP value of 962 IU/L (range: 653-1501). The etiological distribution of rickets included 83.3% nutritional rickets, 12.5% hypophosphatemic rickets, and 4.1% vitamin D-dependent rickets. Compared to the transient hyperphosphatasemia group, children diagnosed with rickets had significantly shorter height, lower calcium and phosphorus levels, and significantly higher PTH and ALP levels (P <0.05). Among patients with ALP levels ≥1000 IU/L, 26.9% (n = 74) comprised 59.5% (n = 44) with transient hyperphosphatasemia, 16.2% (n = 12) with rickets, and 24.3% (n = 18) with other diseases.

Conclusion: Transient hyperphosphatasemia is the most common cause of elevated serum ALP levels in children, followed by various forms of rickets, particularly nutritional rickets. Regular monitoring of ALP levels is sufficient in children with transient hyperphosphatasemia.

Keywords: Alkaline phosphatase elevation, transient hyperphosphatasemia, rickets