A Case of Adult Fanconi Syndrome and Osteomalacia associated with x-Light Chain Monoclonal Gammopathy / 대한내분비학회지

ABSTRACT

The Fanconi syndrome is a complex tubulopathy, which is characterized by urinary hyperexcretion of amino acids of all classes, phosphate, glucose, bicarbonate, calkium, potassium, and otherions, and proteins with molecular weights under 50,000 daltons. This metabolic disease leads to hypophospatemia, hypokalemia, growth failure, metabolic acidasis, and rickets/osteomalacia. Fanconi syndrome may be inherited or acqulred. Most cases of adult Fanconi syndrome are acquired, and the acquired syndrome is associated with thermal burns, exposure to heavy metals or drugs, vitmnin D deficiency, renal transplantation, or light chain deposition. The most common cause of adult Fanconi syndrome is multiple myeloma. We ribe here a case of adult Fanconi syndrome and osteomalacia associated with x-light chain monoclonal gammopathy. A 47-year-old woman presented with multiple bane pain and proximal muscle weakness for 2 years. Laboratory findmgs showed hypophosphatemia, mild hypocalcemia, marked elevation of serum alkaline phosphatase, metabolic acidosis, low 25-OH- vitamm D level and secondary hyperparathyroidism. Urinary excretion of protein, uric acid, phosphate, and glucose was mcreased, and tubular reabsorption of phosphate was decreased to 50%. Protein immunofixation electrophoresis of serum and urine showed x-light chain type monoclonal gammopathy. Bone marrow examination was normal except moderate elevation of plasma cell component(8.8%). The skeletal radiography showed fractures of both lower ribs and pseudofracture in right femoral lesser trochanter. We treated the patient with calcium, 1.25-(OH)2-vitamin D, phosphorus, bicarbonate, and potassium, and her clinical symptoms were gradually relieved.