B45-04 Reduced Bone Mineral Density in Patients With Primary Ciliary Dyskinesia: A Retrospective Analysis of DEXA Scans

Rationale Primary Ciliary Dyskinesia (PCD) is a rare, inherited disorder of muco-ciliary clearance that leads to chronic respiratory infection, airway remodeling, and pulmonary function decline. Prolonged systemic inflammation, hypoxemia, physical inactivity, and corticosteroid exposure may predispose PCD patients to bone demineralization. However, bone health in PCD remains poorly characterized. We aimed to evaluate bone mineral density (BMD) and estimated fracture risk in Puerto Rican PCD patients carrying the founder RSPH4A variant. Methods Retrospective analysis performed on one pediatric and six adult PCD patients (n = 7; 5 females, 2 males; mean age 51.7, range 16-63) followed at the Puerto Rico PCD Center. Demographic, clinical, and dual-energy X-ray absorptiometry (DEXA) data were extracted, including BMI, FEV₁ % predicted, and lumbar spine and femoral neck T-scores. BMD was categorized according to World Health Organization (WHO) criteria: normal (T ≥ −1.0), osteopenia (−2.5 < T < −1.0), and osteoporosis (T ≤ −2.5). Estimated 10-year fracture probabilities were approximated using a FRAX-based heuristic (Fracture Risk Assessment Tool) assuming no clinical risk factors (no prior fracture, parental hip fracture, smoking, rheumatoid arthritis, secondary osteoporosis, or alcohol use). Results The mean BMI was 31.07 ± 10.5 kg/m², and mean FEV₁ % predicted was 53.29 ± 14.9, reflecting moderate-to-severe obstruction. All patients were Hispanic and homozygous for RSPH4A (c.921 + 3_6delAAGT). Chronic bacterial colonization was present in all seven (100%), and six (85.7%) had corticosteroid exposure. Lumbar spine T-scores ranged from −3.3 to + 1.0 (mean −1.11 ± 1.65), and femoral neck T-scores from −2.4 to + 0.4 (mean −1.24 ± 1.02). Based on the lumbar status classification, three patients (43%) had normal BMD, three (43%) had osteopenia, and one (14%) had osteoporosis. Based on the spine status classification, three patients (43%) had normal BMD, two (28.5%) had osteopenia, and two (28.5) had osteoporosis Oxygen-dependent patients demonstrated the lowest T-scores. The estimated 10-year major osteoporotic fracture probability ranged from 5–22% (mean ≈12.2%), while hip fracture risk remained below 4% for all patients. Conclusion Low bone mineral density was highly prevalent in this small cohort of RSPH4A-associated PCD patients, with 71% showing osteopenia or osteoporosis. Despite elevated BMI, bone loss persisted—likely influenced by chronic hypoxemia, inflammation, and corticosteroid exposure. These findings highlight the potential role for routine DEXA screening and targeted bone health interventions in adults with PCD, particularly those with advanced lung disease. Larger multicenter studies are needed to define prevalence, risk factors, and prevention strategies across diverse PCD populations.