ESPE Abstracts (2018) 89 P-P3-038

Infantile Hypophosphatasia

Derya Buleşa & Zehra Aycanb

aKeçiören Research and Educational Hospital, Ankara, Turkey; bYıldırım Beyazıt University, Ankara, Turkey

Hypophosphatasia is characterized by defective mineralization of bone and/or teeth in the presence of low activity of serum and bone alkaline phosphatase. Clinical features range from stillbirth without mineralized bone at the severe end to pathologic fractures of the lower extremities in later adulthood at the mild end. Although the disease spectrum is a continuum, six clinical forms are usually recognized based on age at diagnosis and severity of features: Perinatal (severe) hypophosphatasia characterized by respiratory insufficiency and hypercalcemia. Perinatal (benign) hypophosphatasia with prenatal skeletal manifestations that slowly resolve into one of the milder forms. Infantile hypophosphatasia with onset between birth and age six months of rickets without elevated serum alkaline phosphatase activity. Here we will discuss a 15-month-old girl patient who has been referred to for the reason of delaying teeth.

Case: A 15-month-old girl applied for the delay in tooth extraction. She was born at the 40th week of gestation by Caesarean section with a birthweight of 3200 g as the first child of consanguineous parents. On her physical examination at one month old, her weight was 10.2 kg (50th–75th centile), her height was 74.5 cm (25th–50th centile), and her head circumference was 35.5 cm (10th–25th centile). On laboratuary examination: Ca: 11.3 mg/dl, P:5.8 mg/dl, ALP: 59 IU/l (alt sınır 125 IU/l). 25OH vit D:32.3 ng/ml, PTH: 8.82 pg/ml, 1,25 OH vit D:55 pg/ml, Urinary calcium excretion was normal with a calcium/creatinine ratio of 0.16 Pyridoksal 5 phosfate: 68.40 μg/L (5–50), urine phosphoetanolamin: 895.20 μmol/g kre (33–342).

Genetic analysis: A heterozygous p.S181L (c.542C>T) mutation was detected in ALPL gene.

Conclusion: The clinical characteristics of infantile type of HPP are respiratory complications, premature craniosynostosis, demineralization, rachitic changes in the metaphyses, hypercalcemia, short stature, and premature loss of primary teeth. Clinical features, age, bone mineralization, elevated serum concentrations of calcium and phosphorus, and low serum ALP enzyme activity helps differentiate HPP from other conditions. In the presented patient, HPP was considered with onset after 15 months of age delaying teeth, hypercalcemia, remarkably low level of ALP, and normal PTH level.

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