#2531 Improvement of the diagnostic delay of primary hyperoxaluria

Abstract Background and Aims Primary hyperoxaluria (PH) is a rare recessive autosomal genetic disease leading to abnormalities in the hepatic glyoxylate metabolism. The prognosis of the disease depends, among other factors, on patients’ age, diagnosis delay and time to initiate treatment. A diagnostic delay significantly shorter in children compared with adults (1.2 (0.1–3.0) versus 30 (17–36) years) was reported in a French cohort of PH patients diagnosed between 2015 and 2019. Since then, the development of new treatments, such as lumasiran (an RNA interference therapy), has increased awareness of the disease within the nephrology community. We aimed to evaluate whether education within the nephrology community, following the introduction of this new treatment, has contributed to reducing the diagnostic delay of PH. Method We report on a nationwide retrospective study including all patients that had receive a positive genetic test of PH, from our reference laboratory in Lyon between January 2020 and December 2024. Diagnosis delay was defined by the time between the first symptoms and the genetic test. Results A total of 54 patients were included, 31 (57%) patients were children, 25 (46%) patients were women. Forty-two (78%) patients had PH type 1, 5 (9%) had PH type 2 and 7 (13%) patients had PH type 3. Only two patients were not managed in a University Hospital. The practitioners who requested the genetic analysis were either nephrologists (23, 43%) or pediatricians (31, 57%). The diagnostic delay was still significantly shorter in children as compared to adults (0.5 (0–1.3) versus 14 (0–30) years, P < 0.05). In the pediatric population, two patients were diagnosed antenatally, one was diagnosed post-mortem and five were diagnosed during a family screening without symptoms. In the adult population, one genetic test was done to confirm the diagnosis already made and five were diagnosed during a family screening without symptoms. Conclusion The diagnostic delay for PH has been reduced by half over the past five years, driven by advancements in treatment and improved knowledge and awareness of the disease. This may facilitate earlier management and limit complications with appropriate therapies.