Clinical mismatches leading to the misdiagnosis of multiple myeloma as diabetic nephropathy: A case report

Table 1 Timeline of clinical events and interventions in 2025

Date (2025)	Clinical events and interventions
May	Onset of progressive fatigue and symptoms of anemia
June	Visited hematology clinic; Hb: 66 g/L, Cr: 220 μmol/L. Initial bone marrow cytology showed 5% plasma cells
July 13	Admitted to the Department of Endocrinology for suspected DN
Mid of July	Discovery of the three clinical mismatches (anemia-renal, protein-albumin gap, and lack of hypertension/edema)
Late of July	Performed follow-up bone marrow biopsy and serum free light chain testing
August 10	Confirmed diagnosis of λ-type multiple myeloma (stage III, group B)
August 30	Transferred to hematology; initiated bortezomib and dexamethasone chemotherapy
September 18	Follow-up: Hb rose to 84 g/L, Cr decreased to 147.8 μmol/L. Discharged after remission

Hb: Hemoglobin; Cr: Serum creatinine; DN: Diabetic nephropathy.

Table 2 Comparative analysis of typical diabetic nephropathy vs. manifestations in this patient

Feature	Typical DN	Manifestations in this patient	Clinical significance
Anemia severity	Proportional to CKD stage (Hb approximately 90-100 g/L at eGFR 15-20 mL/minute/1.73 m2)	Severe anemia (Hb nadir 62 g/L)	Disproportionate anemia suggests bone marrow involvement
Proteinuria composition	Primarily albumin (high UACR)	Non-albumin protein (low UACR 52 mg/gvs high 24 hours-TP 1.07 g)	Indicates “overflow” light chains rather than glomerular leak
Blood pressure	Usually hypertensive due to volume overload	Normotensive (110/60 mmHg)	Points toward tubulointerstitial damage over glomerular damage
Edema	Common (systemic/peripheral)	Absent	Inconsistent with volume overload typical of advanced DN
Renal decline	Chronic and gradual progression	Rapidly progressive renal insufficiency	Red flag for NDRD

CKD: Chronic kidney disease; Hb: Hemoglobin; UACR: Urinary albumin-to-creatinine ratio; DN: Diabetic nephropathy; eGFR: Estimated glomerular filtration rate; TP: Total protein; NDRD: Non-diabetic renal disease.