1. Introduction
Multiple myeloma (MM) is the second most common hematological malignancy characterized by the clonal proliferation of plasma cells producing monoclonal immunoglobulins. [ 1 ] Approximately 20% to 40% of patients present with renal impairment at diagnosis, which significantly worsens prognosis and leads to higher early mortality. [ 2 , 3 ] The mechanisms of MM-related renal injury are multifactorial, including light chain deposition, cast nephropathy, hypercalcemia, volume depletion, and nephrotoxic medications. [ 4 , 5 ] Renal dysfunction not only complicates therapeutic decision-making but also limits the tolerability of novel anti-myeloma regimens, making supportive strategies critically important. [ 6 ]
Nutritional management plays a key role in comprehensive care of patients with MM and renal impairment but is often overlooked in practice. [ 7 ] Protein intake regulation is essential for protecting renal function, as excessive protein accelerates nitrogenous waste production, metabolic acidosis, and accumulation of protein-bound uremic toxins. [ 8 ] Traditional low-protein diet (LPD) strategies, however, are frequently implemented as generalized prescriptions without addressing individual differences in metabolism, stage of disease, or nutritional reserve, which may lead to protein-energy wasting and and reduced dietary adherence. [ 9 ]
In recent years, individualized low-protein diet nursing (ILPD) has emerged as a novel strategy. ILPD emphasizes tailoring protein restriction based on renal function, disease stage, inflammatory status, and nutritional needs, while ensuring adequate caloric and essential amino acid intake. [ 10 ] This approach is supported by guidelines such as KDOQI (2020) and KDIGO (2024), which recommend 0.55 to 0.60 g/kg d of protein intake for non-dialysis CKD patients, combined with adequate energy supply and ketoacid supplementation when necessary. [ 7 , 8 ]
Previous studies in chronic kidney disease and oncology populations have suggested that ILPD or very-LPDs supplemented with ketoacids may delay renal progression, reduce metabolic burden, and improve quality of life. [ 9 , 10 ] However, evidence specific to MM with renal impairment remains limited. Therefore, this study was designed to evaluate the 1 year clinical effectiveness of ILPD in 126 MM patients with renal impairment, focusing on renal function, nutritional status, inflammation, and quality of life, providing new evidence for evidence-based nursing management strategies.
2. Materials and methods
2.1. Study design and ethical approval
This study was approved by the Ethics Committee of the First Affiliated Hospital of Soochow University (Approval No. 2023-HEM-126). A total of 126 patients with MM complicated by renal impairment admitted between August 2023 and July 2024 were retrospectively reviewed. All procedures complied with the Declaration of Helsinki. Patient data were anonymized prior to analysis to protect confidentiality. Given the retrospective nature of the study, the requirement for informed consent was formally waived by the Institutional Review Board. This was a retrospective cohort study. All interventions in both the ILPD and control groups were part of routine clinical nursing practice at our hospital during the study period. No additional interventions were introduced for the purpose of this study. Data on dietary prescriptions, nursing measures, laboratory results, and patient outcomes were collected retrospectively from electronic medical records and nursing documentation.
2.2. Patient selection
Eligibility criteria were as follows: age ≥ 18 years; diagnosis of MM established according to International Myeloma Working Group) criteria; renal impairment defined as estimated glomerular filtration rate (eGFR) < 90 mL/min/1.73 m²; and complete medical and nursing records available for review.
Exclusion criteria were: severe hepatic dysfunction, active infection, or other concomitant malignancies; and patients who discontinued treatment within 3 months after enrollment.
2.3. Grouping and interventions
Participants were divided into 2 groups based on dietary management strategies. The ILPD group (n = 64) received personalized protein intake prescriptions (0.6–0.8 g/kg/d), adjusted according to renal function, nutritional status, and patient tolerance. Emphasis was placed on ensuring adequate caloric intake, increasing the proportion of high biological value protein, and providing essential amino acid or ketoacid supplementation when necessary. In addition, nursing staff implemented structured dietary education, individualized counseling, and regular follow-up to ensure adherence.
The control group (n = 62) received conventional dietary nursing, which involved generalized LPD recommendations (0.6–0.8 g/kg/d) without individualized adjustment. Routine measures mainly included brief oral dietary guidance at admission, distribution of hospital-issued dietary brochures, and occasional follow-up by nursing staff during hospitalization or outpatient visits. No systematic individualized counseling, protein quality adjustment, or specific nutritional supplementation was provided. Patients were advised to avoid excessive protein intake but were not monitored or regularly evaluated for dietary adherence.
2.4. Outcome measures
The following clinical outcomes were assessed at baseline and at 12 months of intervention:
Nutritional status: serum albumin (g/L), body mass index (kg/m²);
Renal function: serum creatinine (μmol/L), eGFR (mL/min/1.73 m²);
Inflammatory markers: C-reactive protein (mg/L);
Quality of life: assessed by the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30);
Adverse events: including fatigue, anorexia, hyperkalemia, and other clinically relevant events recorded during follow-up.
2.5. Statistical analysis
All data were analyzed using SPSS version 26.0 (IBM Corp., Armonk). Continuous variables were expressed as mean ± standard deviation and compared between groups using the independent samples t test. Categorical variables were presented as frequencies or percentages and compared using the χ ² test or Fisher’s exact test as appropriate. A 2-sided P value < .05 was considered statistically significant.
3. Results
3.1. Baseline characteristics
There were no statistically significant differences between the ILPD group and the control group in terms of age, gender distribution, disease stage, baseline renal function, and nutritional status (Table 1 ), indicating that the 2 groups were comparable at baseline.
Table 1
Baseline characteristics of patients.
ALB = albumin, eGFR = estimated glomerular filtration rate, ILPD = individualized low-protein diet.
| Variable | ILPD group (n = 64) | Control group (n = 62) | P value |
| Age (yr) | 59.6 ± 10.7 | 60.4 ± 11.3 | .68 |
| Male (%) | 36 (56.3%) | 34 (54.8%) | .87 |
| ISS stage III (%) | 28 (43.8%) | 25 (40.3%) | .71 |
| eGFR (mL/min/1.73 m²) | 55.4 ± 13.5 | 54.8 ± 14.1 | .81 |
| ALB (g/L) | 35.6 ± 4.7 | 35.2 ± 5.0 | .65 |
3.2. Post-intervention clinical outcomes
After 1 year of intervention, the ILPD group exhibited significantly better outcomes compared to the control group. Improvements were observed in nutritional status higher albumin and body mass index levels, improved eGFR, reduced serum creatinine, and decreased C-reactive protein levels. Detailed results are presented in Table 2 and Figure 1 .
Table 2
Comparison of nutritional status, renal function, and inflammation after 1 year.
ALB = albumin, BMI = body mass index, CRP = C-reactive protein, eGFR = estimated glomerular filtration rate, ILPD = individualized low-protein diet, Scr = serum creatinine.
| Variable | ILPD group | Control group | P value |
| ALB (g/L) | 38.2 ± 4.3 | 34.6 ± 4.8 | <.01 |
| BMI (kg/m²) | 22.8 ± 2.5 | 21.9 ± 2.8 | .04 |
| Scr (μmol/L) | 126.5 ± 34.8 | 141.9 ± 39.2 | .02 |
| eGFR (mL/min/1.73 m²) | 62.5 ± 12.7 | 54.2 ± 13.1 | <.05 |
| CRP (mg/L) | 7.3 ± 2.5 | 11.6 ± 3.7 | <.01 |
3.3. Quality of life and adverse events
Quality of life scores (QLQ-C30) were significantly higher in the ILPD group than in the control group, indicating better overall well-being. In addition, the incidence of adverse events such as fatigue, anorexia, and hyperkalemia was lower in the ILPD group. The detailed comparisons are shown in Table 3 and Figure 2 .
Table 3
Comparison of quality of life and adverse events.
ILPD = individualized low-protein diet, QLQ-C30 = quality of life questionnaire-core 30 (EORTC), QoL = quality of life.
| Outcome | ILPD group (n = 64) | Control group (n = 62) | P value |
| QoL score (QLQ-C30) | 70.5 ± 11.4 | 62.8 ± 12.9 | .01 |
| Adverse events (%) | 9 (14.1%) | 19 (30.6%) | .03 |
4. Discussion
This study demonstrated that ILPD significantly improved renal function, nutritional status, inflammation control, and quality of life compared with conventional dietary care. These findings align with earlier studies in non-dialysis CKD patients, where individualized dietary protein restriction showed protective effects against renal decline. [ 11 , 12 ] By optimizing the balance between protein restriction and nutrient adequacy, ILPD reduced nitrogenous waste while preventing malnutrition, providing a safe and feasible dietary intervention for MM patients. [ 13 ]
Mechanistically, ILPD reduces renal metabolic burden by lowering the generation of uremic toxins such as indoxyl sulfate and p-cresyl sulfate, which are implicated in tubulointerstitial injury and systemic inflammation. [ 14 ] At the same time, adequate caloric and essential amino acid supplementation mitigates the risk of protein-energy wasting and sarcopenia, thus preserving treatment tolerance. [ 15 ] Nursing-supervised adherence programs embedded within ILPD further enhance compliance, a factor that has been identified as crucial for long-term effectiveness in CKD nutritional interventions. [ 16 ]
The clinical implications are significant. Renal function recovery in MM is a major determinant of survival, treatment eligibility, and tolerance of proteasome inhibitors or immunomodulatory drugs. [ 17 ] By improving nutritional and inflammatory status, ILPD may synergize with tumor-directed therapies to enhance outcomes, reduce complications, and improve patient-reported quality of life. [ 18 ] Tools such as the EORTC quality of life questionnaire-core 30 (EORTC) offer standardized measures for evaluating the benefits of dietary interventions, further supporting the integration of ILPD into comprehensive care. [ 19 ]
While our findings are consistent with the KDOQI (2020) and KDIGO (2024) guidelines, which recommend individualized protein restriction for CKD patients, few studies have specifically focused on MM with renal impairment. Prior CKD studies demonstrated that low- or very-LPDs supplemented with ketoacids delayed renal progression and improved metabolic outcomes. [ 9 , 10 ] However, MM-related renal impairment involves additional pathophysiological mechanisms such as light chain deposition and treatment-related nephrotoxicity. [ 2 , 4 ] Compared with these CKD studies, our results provide disease-specific evidence showing that individualized protein management not only improved renal function but also reduced systemic inflammation and improved quality of life in MM patients. This highlights both the similarity – namely, the renal-protective role of individualized protein restriction – and the difference, where the benefit extends to cancer-related complications, supporting the clinical value of ILPD in this unique population.
Nonetheless, several limitations should be considered. This was a single-center retrospective study with a relatively small sample size (n = 126) and only one year of follow-up, which may limit the generalizability of our findings to broader MM populations or long-term outcomes. Moreover, due to the retrospective design, systematic assessment of patient dietary compliance was not available, and information regarding protein source distribution and the use of ketoacid supplementation was incomplete. These factors precluded a more detailed mechanistic analysis. Therefore, the observed benefits of ILPD should be interpreted with caution, particularly regarding their long-term durability and applicability to other clinical settings. Future multicenter prospective studies with larger sample sizes, longer follow-up, and standardized adherence assessments are warranted to confirm these findings, refine protein prescription strategies for MM patients with varying renal statuses, and evaluate long-term outcomes such as renal survival and overall survival. [ 20 ]
5. Conclusion
ILPD nursing is effective in managing MM patients with renal impairment, improving renal function, nutritional status, and quality of life while reducing adverse events. It represents a feasible and clinically valuable nursing strategy for this high-risk population.
Author contributions
Conceptualization: Xiao Ling, Meimei Yu.
Data curation: Xiao Ling, Meimei Yu.
Formal analysis: Xiao Ling, Meimei Yu.
Investigation: Xiao Ling, Meimei Yu.
Methodology: Xiao Ling, Meimei Yu.
Validation: Xiao Ling.
Visualization: Xiao Ling, Meimei Yu.
Writing – original draft: Xiao Ling, Meimei Yu.
Writing – review & editing: Xiao Ling, Meimei Yu.
Abbreviations: eGFR estimated glomerular filtration rate ILPD individualized low-protein diet LPD low-protein diet MM multiple myeloma QoL quality of life.
The authors have no funding and conflicts of interest to disclose.
The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.
How to cite this article: Ling X, Yu M. Application of individualized low-protein diet nursing for managing multiple myeloma patients with renal impairment. Medicine 2025;104:50(e46087).
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