Andrea Palermo1, Rocky Strollo1, Rocco Papalia2, Luca D'Onofrio1, Ernesto Maddaloni1, Silvia Irina Briganti1, Nicola Napoli1, Umberto Vespasiani3, Sebastiano Costantino4, Paolo Pozzilli5, Vincenzo Denaro2, Silvia Manfrini1. 1. Department of Endocrinology and Diabetes, University Campus Bio-Medico of Rome, Italy. 2. Department of Orthopedics, University Campus Bio-Medico of Rome, Italy. 3. Department of Hepatology, University Campus Bio-Medico of Rome, Italy. 4. Department of Internal Medicine, University Campus Bio-Medico of Rome, Italy. 5. Department of Endocrinology and Diabetes, University Campus Bio-Medico of Rome, Italy Centre for Diabetes, The Blizard Building, Barts and The London School of Medicine, Queen Mary, University of London, London, United Kingdom.
Abstract
OBJECTIVE: Generalized proximal, type 2, renal tubular acidosis, also known as Fanconi syndrome, is a generalized dysfunction of the proximal renal tubule characterized by impaired reabsorption and increased urinary loss of phosphate and other solutes, such as uric acid, glucose, amino acids, and bicarbonate. Chronic hypophosphatemia is the second most common cause of osteomalacia after vitamin D deficiency in adult patients and can have a heterogeneous presentation, ranging from mild symptoms such as muscle weakness and skeletal pain to more severe presentation, such as disabling myopathy, severe bone and joint pain, difficulty walking, and even bone fractures. METHODS: This report describes a case of severe hypophosphatemic osteomalacia with multiple fragility fractures induced by adefovir, which was worsened and confounded by a previous treatment with zoledronic acid and required prolonged intravenous potassium phosphate administration. RESULTS: We highlight the limited diagnostic value of dual X-ray absorptiometry and bone scintigraphy in this challenging diagnosis. Bone metabolism should always be assessed in patients treated with adefovir for early detection of osteomalacia due to Fanconi syndrome. CONCLUSION: Although rare, this condition may be life-threatening and mimic other bone metabolic disorders that are treated with drugs that may further impair phosphate balance.
OBJECTIVE: Generalized proximal, type 2, renal tubular acidosis, also known as Fanconi syndrome, is a generalized dysfunction of the proximal renal tubule characterized by impaired reabsorption and increased urinary loss of phosphate and other solutes, such as uric acid, glucose, amino acids, and bicarbonate. Chronic hypophosphatemia is the second most common cause of osteomalacia after vitamin D deficiency in adult patients and can have a heterogeneous presentation, ranging from mild symptoms such as muscle weakness and skeletal pain to more severe presentation, such as disabling myopathy, severe bone and joint pain, difficulty walking, and even bone fractures. METHODS: This report describes a case of severe hypophosphatemic osteomalacia with multiple fragility fractures induced by adefovir, which was worsened and confounded by a previous treatment with zoledronic acid and required prolonged intravenous potassium phosphate administration. RESULTS: We highlight the limited diagnostic value of dual X-ray absorptiometry and bone scintigraphy in this challenging diagnosis. Bone metabolism should always be assessed in patients treated with adefovir for early detection of osteomalacia due to Fanconi syndrome. CONCLUSION: Although rare, this condition may be life-threatening and mimic other bone metabolic disorders that are treated with drugs that may further impair phosphate balance.