This document summarizes the causes, pathophysiology, and management of acute kidney injury in multiple myeloma. It notes that nearly 20% of multiple myeloma patients present with severe renal impairment and 10% require dialysis. The most common cause of AKI is cast nephropathy due to excess light chains precipitating in the kidney. Management involves correcting underlying causes like hypercalcemia, hydration, and chemotherapy to reduce light chain levels. Plasma exchange may help dialysis-dependent patients, though randomized trials show limited benefit. Recovery of renal function is associated with improved survival.

1. AETIOLOGY AND MANAGEMENT OF ACUTE KIDNEY
INJURY IN MULTIPLE MYELOMA
BEN SPRANGERS
NEPHROLOGY DIALYSIS TRANSPLANTATION-2018

2. REVISED INTERNATIONAL MYELOMA WORKING GROUP DIAGNOSTIC
CRITERIA FOR MULTIPLE MYELOMA AND SMOULDERING MULTIPLE
MYELOMA (2014)
 Clonal bone marrow plasma cells ≥10%
or
biopsy-proven bony or extramedullary plasmacytoma*
and
any one or more of the following myeloma defining events:
• Hypercalcaemia: serum calcium >0·25 mmol/L (>1 mg/dL) higher than the upper limit of normal or >2·75
mmol/L (>11 mg/dL)
• Renal insuffi ciency: creatinine clearance 177 μmol/L (>2 mg/dL)
• Anaemia: haemoglobin value of >2 g/dL below the lower limit of normal, or a haemoglobin value <10g /dl
• Bone lesions: one or more osteolytic lesions on skeletal radiography, CT, or PET-CT
• Involved:uninvolved serum free light chain ratio ≥100, or involved free light chain concentration >10m/dl

3. OR
NONE OF THE ABOVE
BUT
Clonal bone marrow plasma cell percentage* ≥60%

4. EPIDEMIOLOGY
 Nearly 20% of patients have a serum creatinine concentration greater than 2.0 mg/dL,
 10% of patients require dialysis on presentation.
 Recovery of renal function occurs in fewer than 25% of patients who require dialysis.
 AKI is associated with higher mortality, but this may be reflective of more advanced disease in these
patients

5. CAUSES
mIg INDEPENDENT FACTORS
 volume depletion
 hypercalcaemia,
 hyperuricaemia,
 nephrotoxic agents [radiocontrast agents, non-steroidal anti-inflammatory drugs (NSAIDs) and renin–
angiotensin system inhibitors]
 sepsis
 rhabdomyolysis.

6. SPECTRUM OF RENAL INVOLVEMENT
 Cast nephropathy
 light-chain deposition disease
 AL amyloidosis.
 Cryoglobulinemia
 proliferative glomerulonephritis
 heavy chain deposition disease
 immunotactoid glomerulonephritis

7. PATHOPHYSIOLOGY

8. Renl clearance of
kappa=lambda
Kappa/lambda -0.37-3.17

9. CAST NEPHROPATHY
Increased IL6,IL8,CCL2,TGFβ2
• Interact with Tamm Horsfall protein
and precipitatecasts
Progressive interstitial
inflammation and fibrosis

10. CAST NEPHROPATHY
 Most common cause of AKI
 Excess light chains precipitate with Tamm-Horsfall mucoprotein secreted by the thick ascending limb of the loop of Henle
and produce casts in the distal tubule.
 ADD on triggers-hypercalcemia, volume depletion, diuretics, and nonsteroidal anti-inflammatory drugs
 Clinical features-
 elderly patient with unexplained renal failure, anemia, and bone pain
 Subnephrotic proteinuria
 Histologically, casts are eosin positive, fractured, and waxy in appearance on light microscopy. ,Multinucleated giant cells
surrounding casts, and an interstitial inflammatory infiltrate  Widespread tubular atrophy and interstitial fibrosis
 Immunofluorescence stain-light-chain restriction within the casts. The glomeruli and vessels appear normal, unless light-
chain deposition disease is concurrently present.
 diagnosis of light chain CN can be made presumptively if the circulating FLC levels are high (>500mg/L) in the presence of
MM and AKI

11. Casts have a lattice-like appearance having needle-shaped crystals on electron microscopy

13. LIGHT CHAIN DISEASE
 Clinical features- Nephroticrange proteinuria, Hypertension, microscopic hematuria
 hallmark-development of mesangial nodules secondary to the upregulation of PDGF-β and TGF-β
 Nodular sclerosing glomerulopathy

15. • On light microscopy, mesangial nodules more uniform in distribution and size than in diabetic nephropathy
• Irregular thickening and double contours of the glomerular basement membrane may also be present
• Eosin-positive deposits may be seen diffusely throughout tubular basement membranes
• Immunofluorescence studies-characteristic linear staining of basement membranes with monotypic light
chains, which are most commonly κ restricted.
• On electron microscopy, granular powder deposits are distributed within the mesangium and midportion of the
glomerular, tubular, and vessel wall basement membrane

16. AL AMYLOIDOSIS
 AL amyloidosis occurs when pathogenic light chains unfold and deposit as insoluble fibrils extracellularly
within tissues
 Nephrotic syndrome

19. PROXIMAL RTA
 One of the most common cause of acquired proximal RTA in adults
 increased excretion immunoglobulin light chains injures the proximal tubule epithelium
 light chains in multiple myeloma have variable domain resistant to degradation by proteases in
lysosomes in proximal tubule cells.
 Accumulation of the variable domain fragments may be responsible for the impairment in tubular
function

20. OTHER CAUSES
 acute tubular necrosis (ATN) secondary to sepsis or nephrotoxic antiinfective drugs, tumor lysis
syndrome after therapy
 Hyperviscosisty syndrome
 Osteoclast-mediated bone destruction  hypercalcemia ATN,interstitial nephritis, nephrogenic
diabetesinsipidus, or nephrolithiasis.
 Tubular damage from the lightchain depositsnephrogenic diabetes insipidus.
 Rarely, malignant plasma cells may directly invade the kidney AKI
 Hyporeninemic hypoaldosteronism

21. MANAGEMENT
 Correction of hypercalcemia , aggressive hydration, alkalinisation of the urine
 Avoidance of nonsteroidal antiinflammatory drugs and intravenous radiocontrast agents.
 Steroids may be utilized to acutely decrease the burden of circulating light chains until more definitive
chemotherapy can begin
 Reduction of FLC levels can be obtained by the rapid initiation of cytotoxic chemotherapy and by
performing plasmapheresis/high cut-off haemodialysis (HCO-HD).
 Studies of the effectiveness of plasmapheresis in the treatment of myeloma cast nephropathy have
yielded conflicting results

22. VISTA TRIAL
 Velcade as Initial Standard Therapy in multiple myeloma: Assessment with melphalan and Prednisone
(VISTA) trial
 compared the efficacy of bortezomib plus melphalan and prednisone (VMP) and melphalan and
prednisone (MP) in previously untreated MM-CN patients with renal impairment.
 Renal impairment reversal [baseline glomerular filtration rate (GFR) <50 improving to >60mL/min/1.73
m2]
 seen in 44% of VMP-treated patients versus 34% of MP-treated patients.
 Younger age and less severe impairment at baseline were identified as predictors of renal impairment
reversal

23. DIALYSIS/PLASMAPHARESIS
 7% MM patients will present with dialysis dependent AKI
 role of plasmapheresis or HCO-HD to remove FLC in these patients is controversial.
 randomized trials indicate a lack of benefit.
 In a recent French randomized clinical trial (MYRE)- HCO-HD compared with conventional HD did not
result in a statistically significant difference in HD independence at 3months
 Eulite Trial there was no difference in dialysis independence at 3 months in patients treated with HCO-
HD compared with conventional HD and also there were significantly more episodes of lung infection in
the HCO-HD group.
 Therefore, we recommend plasmapheresis/HCO-HD only in the context of trials.

24.  Survival is reduced to <1 year in MM patients with AKI who do not recover renal function
 reversibility of MM-associated AKI is an important predictor of patient survival