Landscape extraordinariness and visitors' psychological restoration in national park settings: a chain mediation model of awe, construal level, and connectedness to nature.

Tumor-induced osteomalacia (TIO) is an ultra-rare condition caused by tumors, typically phosphaturic mesenchymal tumors (PMT), secreting fibroblast growth factor-23 (FGF23) (). Elevated FGF23 levels lead to impaired renal phosphate reabsorption resulting in chronic hypophosphatemia and low serum 1,25-dihydroxyvitamin D levels (, ). The clinical manifestations of TIO include severe musculoskeletal morbidities such as fractures and proximal muscle weakness, pain, fatigue, and impaired mobility (). Patients with TIO often experience lengthy diagnostic delays, due to limited disease awareness among providers because of the rarity of the condition and symptom overlap with other musculoskeletal, rheumatologic, or neurologic disorders (). Diagnosis often involves visits to multiple specialists, a range of biochemical tests (including serum phosphate, intact FGF23, and tubular maximum phosphate/glomerular filtration rate), and structural or functional imaging (including magnetic resonance imaging, octreoscans, DOTATATE-/FDG-positron emission tomography/computed tomography) (, ). Where possible, complete tumor resection is the definitive treatment for TIO. Alternatively, image guided ablation may be used to treat inoperable or residual tumors. However, localizing the causative tumor(s) is often difficult due to small size, variable tumor location, and limited sensitivity of detection methods. For patients with TIO whose tumors cannot be localized or curatively resected, the traditional treatment has been multiple daily doses of oral phosphate and active vitamin D analogs (). However, this therapy is associated with tolerability issues and complications, such as gastrointestinal distress, hypercalcemia, nephrocalcinosis, and tertiary hyperparathyroidism ().