A case of multiple myeloma presenting as a distal renal tubular acidosis with extensive bilateral nephrolithiasis

Abstract

Background: At the time of diagnosis, Multiple Myeloma is commonly associated with renal impairment. Renal tubular acidosis without overt renal insufficiency is an uncommon disease presentation of myeloma. Among tubular acidosis types, isolated renal tubular acidosis is a very unusual presentation of multiple myeloma. Case presentation: We present a 55 years old female who presented with lower limb weakness due to persistent hypokalaemia caused by distal renal tubular acidosis. On further investigation of her anaemia with high erythrocyte sedimentation rate, we diagnosed IgG myeloma. Conclusion: Isolated distal renal tubular acidosis is a rare presentation of multiple myeloma. In the absence of hypercalciuria and demonstrable light chain excretion in urine, we assumed that the distal renal tubular acidosis could have been caused by monoclonal hypergammaglobulinaemic state of multiple myeloma.