J Clin Res Pediatr Endocrinol. 2012; 4(1): 34-38 | DOI: 10.4274/jcrpe.473

Hypophosphatasia Presenting with Pyridoxine-Responsive Seizures, Hypercalcemia, and Pseudotumor Cerebri: Case Report

Hüseyin Demirbilek¹, Yasemin Alanay², Ayfer Alikaþifoðlu¹, Meral Topçu³, Etienne Mornet⁴, Alev Özön¹, Nurgün Kandemir^1
1Hacettepe University Faculty Of Medicine, Department Of Pediatrics Endocrinology, Ankara, Turkey
²Hacettepe University Faculty Of Medicine, Department Of Genetics, Ankara, Turkey
³Hacettepe University Faculty Of Medicine, Department Of Pediatric Neurology, Ankara, Turkey
⁴Université De Versailles Saint Quentin En Yvelines, France

Hypophosphatasia (HPP) is an inborn error of metabolism characterized by defective bone mineralization caused by a deficiency in alkaline phosphatase (ALP) activity due to mutations in the tissue-nonspecific ALP (TNALP) gene. The clinical expression of the disease is variable. Six forms of HPP are identified according to age at presentation and clinical features. Patients with the infantile form are normal at birth. First symptoms appear within the first 6 months of life. Along with skeletal findings, HPP patients may present with hypercalcemia, seizures, pseudotumor cerebri, and pulmonary insufficiency. Seizures in HPP are refractory to conventional antiepileptic drugs, but are responsive to pyridoxine. Herein, we report a case of HPP who presented with pyridoxine-responsive seizures in the early neonatal period and was found to have hypercalcemia, skeletal demineralization and increased intracranial pressure.

Keywords: Hypophosphatasia,pyridoxine-responsive seizures,bisphosphonates,Alkaline phosphatase,bone resorption,hypercalcemia

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