SAT-LB66 X Linked Rickets: Description of 16 Cases in the Adulthood in Argentina

Introduction. X-linked hypophosphatemic rickets (XLH) is an inherited disorder that results from an inactivating mutation of the PHEX gene. The familiar form comprises most cases. Its incidence is 4.8 per 100000 persons (Haffner D et al., 2019). XLH is characterized by bowed or bent legs, short stature, tooth abscesses, hearing loss, joint pain and impaired mobility, which can alter quality of life. Aim. To describe clinical characteristics, laboratory and imaging findings of XLH adult patients attending to our hospital; to evaluate physical function and impact on the quality of life; to estimate adherence to conventional treatment. Methods. A retrospective, observational study from 16 XLH patients medical records was performed. Age, sex, BMI, age at diagnosis, number of fractures, bone deformities, corrective surgeries, biochemical and genetic profile were evaluated. Physical functionality, pain and stiffness were measured with WOMAC (Bellamy N et al., 1988) and PROMIS scale; and QOL with SF36. Adherence to treatment was assessed with the CQR questionnaire. To monitor treatment complications renal ultrasound and brain CT scan were performed. Results. 16 patients were evaluated, 14 (88%) female, 2 (12%) male, with a mean (☐) age 40.06 years (± 12.4), Age at diagnosis (12%) male, with a mean:12.68 years (SD ± 18.37), BMI ☐:38.5 kg/m(2) (13.07), stature ☐:129.9 cm (± 33.9), fractures 8/16 (50%) and skeletal deformities 16/16 (100%), number of corrective surgeries required 15/16 (94%), pseudofractures 13/16 (81%), kyphoscoliosis 8/16 (50%). Laboratory: calcemia ☐:9.5 mg/dl (± 0.37), phosphatemia ☐:2.07 mg/dl (± 0.41), PTH ☐:88.31 pg/ml (± 36.1), 25OHD ☐:26,77 ng/ml (± 11.48), RTP ☐:76.76% (± 11.19), FAO ☐:37.08 (± 26.94), CTX ☐:1646 (± 1119), FGF23 ☐:58.85 pg/ml (± 27.7). Genetic profile: 1/14 had a definitely pathogenic not previously described in the literature mutation. 14/16 (88%) patients showed NOT to adhere to conventional treatment. Application of WOMAC function scale ☐:47.87 (± 25.23); PROMIS ☐:31.5 questionnaire (± 9.23); SF36 ☐:34.95 (± 8.5). Renal ultrasound abnormalities 2/16 (13%) nephrocalcinosis and 3/16 (19%) renal lithiasis; no brain calcifications in the CT were described. Conclusion. We note that the high percentage of patients not adherent to conventional treatment leads to marked impaired physical function with important skeletal deformities, fractures and pseudofractures, bone pain and altered QOL. Early diagnosis, adequate treatment and follow-up by a multidisciplinary team will avoid complications and improve the patient’s quality of life.