Renal Impairment in Multiple Myeloma: A Single-Center Cohort Study from Tbilisi, Georgia

Renal impairment is a frequent and clinically significant complication of multiple myeloma (MM), contributing to poor prognosis and delayed diagnosis.
This study aimed to characterize the spectrum of renal involvement, timing of nephrology referral, and clinical outcomes among patients with MM treated at our center between 2022 and 2025.
Importantly, this study represents the first structured and comprehensive effort to systematize and analyze data collected at one of the largest  hospitals in Tbilisi, Georgia — providing a national reference point for MM-associated renal disease and establishing a foundation for multicenter collaboration across the region.

We retrospectively analyzed 195 consecutive patients with confirmed MM. Among them, 59 (30%) presented with renal function decline, defined as reduced eGFR or dialysis dependence at diagnosis.
Clinical, biochemical, and histopathological data were collected. Timing of nephrology referral, kidney biopsy findings, dialysis dependence, and outcomes following autologous stem cell transplantation (ASCT) were evaluated.

A total of 59 patients were included in this single-center cohort.
The mean age at diagnosis was 63.3 years (median 63.0; IQR 57.0–71.0; range 44–79 years).
The cohort comprised 32 males (54.2%) and 27 females (45.8%), reflecting a slight male predominance consistent with previously reported epidemiologic patterns.

Of the 59 patients with renal impairment, 34 (58%) had κ light-chain disease, 12 (20%) λ, 2 (3%) both, and 11 (19%) undetermined type.
Renal biopsy was performed in 13 patients, revealing diverse pathology including AL amyloidosis, light-chain cast nephropathy (LCCN), light-chain deposition disease (LCDD), and PGNMID.
At presentation, the median eGFR was 35 mL/min/1.73 m² (IQR 10–60), and 21 patients (36%) required dialysis; two subsequently became dialysis-independent.
Twenty-four patients (41%) were first referred to a nephrologist before hematologic diagnosis, typically due to unexplained renal failure.

A total of 41 patients (69%) underwent ASCT. Among them, 17 (41%) died during follow-up compared with 4 (22%) deaths among 18 non-transplanted patients.
Overall, survival was higher among patients who underwent ASCT, while those presenting with dialysis-dependent renal failure experienced markedly worse outcomes (9 of 12 transplanted vs 1 of 6 non-transplanted deaths).

Renal involvement in MM was confirmed through a combination of biochemical markers (free light-chain assay, proteinuria quantification) and histopathology when indicated.
Kidney biopsy established specific diagnoses such as AL amyloidosis, light-chain cast nephropathy, and LCDD, guiding therapeutic decisions.
In several cases, renal dysfunction was the initial manifestation that prompted hematologic evaluation and the definitive diagnosis of MM.

Renal impairment occurred in nearly one-third of MM patients, often representing the first clinical manifestation.
Early nephrology involvement and renal biopsy provided critical diagnostic insights.
Despite severe baseline renal dysfunction (median eGFR 35), patients undergoing ASCT demonstrated superior outcomes compared with those managed conservatively.
This work provides the first systematically analyzed Georgian cohort of myeloma-associated kidney disease, offering a valuable framework for national data integration and future international collaboration.