POS1137 IDENTIFYING ADULT HYPOPHOSPHATASIA IN THE RHEUMATOLOGY UNIT

Background: The most frequent manifestation in adult Hypophosphatasia (HPP) is musculoskeletal pain.1,2 The unspecific nature of its clinical presentation may prevent correct diagnosis.3 Objectives: Identifying adult hypophosphatasia in the rheumatology unit. Methods: Over a period of 10 years 9,522 patients were screened in a rheumatological outpatient unit. Serum ALP levels ≤ 40 U/l were found in 524 patients. After screening for secondary causes, 73 patients were invited for clinical evaluation. Genetic testing was performed in 23 patients with suspected HPP. Logistic regression models were used to estimate the association of each clinical factor with HPP. Results: Mutations in the ALPL gene were observed in 57% of genetically screened patients. Arthralgia, fractures and pain were the leading symptoms in HPP patients. Chondrocalcinosis (OR 29.12; 95% CI 2.02-1593.52) and dental disease (OR 8.33; 95% CI 0.93-143.40) were associated with HPP independent of BMI. Onset of symptoms in HPP was at 35.1 (14.3) years, with a mean duration from symptoms to diagnosis of 14.4 (8.1) years. Bone mineral density (BMD) and trabecular bone score (TBS) as well as bone turnover markers were not indicative for HPP. Conclusion: HPP can mimic joint diseases.4 Thus, in patients with uncertain rheumatologic complaints and low ALP, HPP should be considered as potential diagnosis. References: [1]Durrough C, Colazo JM, Simmons J, et al. Characterization of physical, functional, and cognitive performance in 15 adults with hypophosphatasia. Bone 2021;142:115695. [2]Seefried L, Kishnani PS, Moseley S, et al. Pharmacodynamics of asfotase alfa in adults with pediatric-onset hypophosphatasia. Bone 2021;142:115664. [3]Hogler W, Langman C, Gomes da Silva H, et al. Diagnostic delay is common among patients with hypophosphatasia: initial findings from a longitudinal, prospective, global registry. BMC musculoskeletal disorders 2019;20(1):80. [4]Seefried L, Dahir K, Petryk A, et al. Burden of Illness in Adults With Hypophosphatasia: Data From the Global Hypophosphatasia Patient Registry. Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 2020;35(11):2171-78. Disclosure of Interests: None declared.