Frequency of Ectopic Calcifications Among Patients With Hypophosphatasia in the Global HPP Registry

Abstract Ectopic calcifications have been observed in patients with hypophosphatasia (HPP)—a rare, inherited, metabolic disorder characterized by reduced enzymatic activity of tissue nonspecific alkaline phosphatase. The natural history these is poorly understood. Using data from the Global HPP Registry, a cross-sectional, observational analysis was conducted to better understand prevalence nephrocalcinosis and eye absence treatment enzyme replacement therapy, asfotase alfa. association between hypercalcemia (serum calcium ≤10.3 mg/dL [normal]; 10.4–11.9 [mild hypercalcemia]; ≥12.0 [moderate severe hypercalcemia]) ectopic calcification also evaluated. Of study population renal ultrasound (n=327), 11.0% had nephrocalcinosis; no nephrocalcinosis. In children (aged <18 years; n=174), 13.2% nephrocalcinosis, median age at first diagnosis 4 years (range: 0–17 years). adults ≥18 n=153), 8.5% 52 27–72 Data on serum levels were available for 318 ultrasounds. patients, 73 (23.0%) hypercalcemia, whom 10 (13.7%; children: n=9; adults: n=1) moderate (n=7), 6 (85.7%) diagnosed majority (68.8%) did not documented hypercalcemia. who ophthalmological assessments (n=137), (4.4%) calcifications; or calcifications. 16 15–16 years) 51 30–57 adults. 80 assessments. Coexistence reported only 3 all mild hypercalcemia; remaining exhibited No this presented both These results indicate that low during course disease, being more common than addition, higher suggests very high may be risk factor some patients. Future studies are needed assess impact alfa HPP.