SAT-733 A Case of Paget’s Disease of Bone in a Patient with Chronic Liver Disease

Abstract Disclosure: S. Stefan: None. A. Fagin: None. Introduction: Paget’s disease of bone (PDB) is relatively rare, affecting 1-3% of adults over 50, with higher prevalence in individuals of European descent. It is characterized by excessive osteoclastic bone resorption followed by disorganized osteoblastic formation, leading to weak, deformed bones prone to fractures. Most cases are asymptomatic and diagnosed incidentally through elevated alkaline phosphatase (ALP) levels and bone imaging. When symptomatic, patients may experience bone pain, deformities, arthritis, or complications like hearing loss. This case highlights an unusual presentation of PDB in a young woman, where chronic ALP elevation due to liver disease obscured the diagnosis. Case Presentation: A 36-year-old Hispanic woman with chronic liver disease, secondary to a combination of autoimmune hepatitis and primary biliary cirrhosis, presented for evaluation of abnormal DXA scan as part of her workup for liver transplantation. Her medical history also included a brain aneurysm complicated by cerebrovascular accident (CVA) and vitamin D deficiency. Serum alkaline phosphatase (ALP) was consistently elevated (>500 U/L; <130 U/L) for at least 15 years, dating back to the age of 21. Liver function tests showed AST 71 U/L (<37 U/L), ALT 71 U/L (<30 U/L), and gamma-glutamyl transferase (GGT) 298 U/L (<50 U/L). Vitamin D25 was low at 15.1 ng/mL (30-60 ng/mL). Phosphate and calcium levels were normal. Bone turnover markers were elevated, with bone-specific ALP at 94.0 mcg/L (5.0-18.2 mcg/L) and C-telopeptide at 1017 pg/mL (60-650 pg/mL). A whole-body bone scan revealed irregular uptake involving the calvarium, most pronounced in the occipital and temporal bones, raising suspicion for Paget's disease. Despite the absence of bone pain, the patient reported hearing loss, chronic headaches, and dizziness, which had previously been attributed to her brain aneurysm and CVA. Prior imaging of the brain (both CT and MRI) did not reveal any bone abnormalities. There was no family history of Paget's disease. Given the clinical, biochemical and radiological findings, she was treated with a single dose of Zoledronic acid 5 mg. Within a short period, she experienced marked clinical improvement in both her headache and hearing loss. Bone-specific ALP decreased to 35.1 mcg/L (5.0-18.2 mcg/L) at 5 months post-treatment. Conclusion: Paget’s disease of bone (PDB) is extremely rare before age 40, affecting less than 1% of individuals in this group, and requires a high level of suspicion. Early diagnosis and treatment can slow disease progression, prevent complications, and improve quality of life. This case underscores the importance of considering bone disease as a cause of elevated ALP in young patients with liver disease. Monitoring for PDB recurrence in patients with liver disease is challenging, as ALP may not normalize, necessitating lifelong following of bone-specific ALP levels. Presentation: Saturday, July 12, 2025