{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,30]],"date-time":"2026-03-30T10:34:31Z","timestamp":1774866871029,"version":"3.50.1"},"reference-count":27,"publisher":"The Endocrine Society","issue":"3","license":[{"start":{"date-parts":[[2025,8,25]],"date-time":"2025-08-25T00:00:00Z","timestamp":1756080000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/pages\/standard-publication-reuse-rights"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,2,20]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>In X-linked hypophosphatemia (XLH), phosphate and vitamin D analogs increase the risk of nephrocalcinosis and renal impairment. Kidney function assessment is challenging, as creatinine-based estimated glomerular filtration rate (eGFR) may overestimate GFR because of reduced muscle mass. Cystatin C alternatively may be used. Moreover, fibroblast growth factor 23 (FGF23) has been suggested to potentially impact GFR, leading to hyperfiltration and complicating kidney function assessment.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We conducted a single-center retrospective study on adults with XLH to compare eGFR formulas (CKD-EPIcreat, CKD-EPIcyst) with true measured GFR (mGFR). Bias, precision, and accuracy were calculated. In a subgroup, mGFR changes after burosumab initiation were assessed. Finally, we analyzed the FGF23\/GFR relationship in a pediatric cohort in whom FGF23 was also hypersecreted (fibrous dysplasia) to support our hypothesis that FGF23 leads to hyperfiltration.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>We included 20 patients (17 females, median age 35 years). None had nephrocalcinosis or hypercalciuria, but 8 had secondary hyperparathyroidism. Median mGFR was 90 (85-107) mL\/min\/1.73 m\u00b2, significantly lower than CKD-EPIcreat (125 [114-121]) and CKD-EPIcyst (103 [118]) (respectively P &amp;lt; .0001 and P = .01). Bias was significantly greater with CKD-EPIcreat (\u221222 [\u221229 to \u221213]) than CKD-EPIcyst (\u221213 [\u221219 to \u22124]), with lower accuracy (25% vs 93%). In 5 patients with XLH, mGFR decreased from 98 to 84 mL\/min\/1.73 m\u00b2 after burosumab introduction. FGF23 moderately correlated with eGFR in 14 fibrous dysplasia patients (R = 0.62, P = .02).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>eGFR overestimates GFR in XLH, increasing CKD misclassification risk. Annual cystatin C measurement is recommended if CKD is suspected. FGF23 impact on GFR should also be considered in burosumab-treated patients.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1210\/clinem\/dgaf459","type":"journal-article","created":{"date-parts":[[2025,8,23]],"date-time":"2025-08-23T11:40:04Z","timestamp":1755949204000},"page":"e885-e891","source":"Crossref","is-referenced-by-count":1,"title":["Challenges in Estimating Renal Function in X-linked Hypophosphatemia Because of Formula Overestimation and FGF23 Effects"],"prefix":"10.1210","volume":"111","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3460-2507","authenticated-orcid":false,"given":"Sandrine","family":"Lemoine","sequence":"first","affiliation":[{"name":"Service de N\u00e9phrologie, Dialyse, Exploration Fonctionnelle R\u00e9nale, H\u00f4pital Edouard Herriot, Hospices Civils de Lyon , Lyon 69003 ,","place":["France"]},{"name":"Facult\u00e9 de M\u00e9decine Lyon Est, Universit\u00e9 de Lyon , Lyon 69003 ,","place":["France"]},{"name":"INSERM CARMEN 1060 IRIS Team , Lyon 69029 ,","place":["France"]},{"name":"Centre de R\u00e9f\u00e9rence Maladie R\u00e9nale Rare (MAREGE), Fili\u00e8re ORKID , Bron 69003 ,","place":["France"]},{"name":"Centre de R\u00e9f\u00e9rence des Maladies Rares du Calcium et du Phosphore (Fili\u00e8re OSCAR) , Bron 69029 ,","place":["France"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Aur\u00e9lie","family":"De Mul","sequence":"additional","affiliation":[{"name":"Service de N\u00e9phrologie, Dialyse, Exploration Fonctionnelle R\u00e9nale, H\u00f4pital Edouard Herriot, Hospices Civils de Lyon , Lyon 69003 ,","place":["France"]},{"name":"Facult\u00e9 de M\u00e9decine Lyon Est, Universit\u00e9 de Lyon , Lyon 69003 ,","place":["France"]},{"name":"INSERM CARMEN 1060 IRIS Team , Lyon 69029 ,","place":["France"]},{"name":"Centre de R\u00e9f\u00e9rence Maladie R\u00e9nale Rare (MAREGE), Fili\u00e8re ORKID , Bron 69003 ,","place":["France"]},{"name":"Centre de R\u00e9f\u00e9rence des Maladies Rares du Calcium et 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R\u00e9f\u00e9rence Maladie R\u00e9nale Rare (MAREGE), Fili\u00e8re ORKID , Bron 69003 ,","place":["France"]},{"name":"Centre de R\u00e9f\u00e9rence des Maladies Rares du Calcium et du Phosphore (Fili\u00e8re OSCAR) , Bron 69029 ,","place":["France"]},{"name":"CNRS UMR 5305, University of Lyon 1 , Lyon 69007 ,","place":["France"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Roland","family":"Chapurlat","sequence":"additional","affiliation":[{"name":"Facult\u00e9 de M\u00e9decine Lyon Est, Universit\u00e9 de Lyon , Lyon 69003 ,","place":["France"]},{"name":"Centre de R\u00e9f\u00e9rence des Maladies Rares du Calcium et du Phosphore (Fili\u00e8re OSCAR) , Bron 69029 ,","place":["France"]},{"name":"Service de Rhumatologie, h\u00f4pital Edouard Herriot, Hospices Civils de Lyon , Lyon 69003 ,","place":["France"]},{"name":"INSERM UMR 1033LYOS , Lyon 69372 ,","place":["France"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Emmanuelle","family":"Vignot","sequence":"additional","affiliation":[{"name":"Centre de R\u00e9f\u00e9rence des Maladies Rares du Calcium et du Phosphore (Fili\u00e8re OSCAR) , Bron 69029 ,","place":["France"]},{"name":"Service de Rhumatologie, h\u00f4pital Edouard Herriot, Hospices Civils de Lyon , Lyon 69003 ,","place":["France"]},{"name":"INSERM UMR 1033LYOS , Lyon 69372 ,","place":["France"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"M\u00e9lanie Alice","family":"Legrand","sequence":"additional","affiliation":[{"name":"Centre de R\u00e9f\u00e9rence des Maladies Rares du Calcium et du Phosphore (Fili\u00e8re OSCAR) , Bron 69029 ,","place":["France"]},{"name":"Service de Rhumatologie, h\u00f4pital Edouard Herriot, Hospices Civils de Lyon , Lyon 69003 ,","place":["France"]},{"name":"INSERM UMR 1033LYOS , Lyon 69372 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