Rapidly Progressive Renal Failure in Young Adult: An Atypical Presentation of Multiple Myeloma - A Case Report

Introduction: Patients frequently present with renal impairment that does not fit the criteria for acute kidney injury or chronic kidney disease. This condition, known as rapidly progressive renal failure (RPRF), encompasses a diverse range of clinical syndromes characterized by the progressive renal impairment over days to weeks. Case Report: We present a case of a 37-year-old male with a short history of uremic symptoms and decreased urine output with no significant history or examination findings except pallor. The patient had a creatinine of 1.6 mg/dL in April 2022, rising to 4.4 mg/dL, then 11.6 mg/dL during May, 17.6 mg/dL in June, presented to us with a creatinine of 24.6 mg/dL, with normal kidney size and corticomedullary differentiation (CMD). Beta-2-microglobulin was elevated, and renal biopsy showed features suggestive of multiple myeloma (MM). Atypical appearing tubular casts showing 3+ patternless staining for kappa light chains and negativity for lambda light chains were observed. The patient was started on chemotherapy for MM, and renal function was gradually improving. Conclusion: Renal failure as the sole presentation of MM is rare, especially in young adults. This case emphasizes an atypical RPRF, particularly given the patient’s young age.