Lupus Nephritis

Question 1

What is the primary cause of lupus nephritis?

Answer 1

Lupus nephritis is caused by immune complex deposition in the glomerulus, leading to complement activation, inflammation, and renal damage.

Question 2

Which patients with systemic lupus erythematosus (SLE) should undergo a kidney biopsy?

Answer 2

• Patients with significant proteinuria (>500 mg/day)
• Patients with active urinary sediment (hematuria, RBC casts, dysmorphic RBCs)
• Patients with worsening renal function (rising creatinine)

Question 3

What are the six classes of lupus nephritis, and which has the worst prognosis?

Answer 3

• Class I: Minimal mesangial (asymptomatic)
• Class II: Mesangial proliferative (microscopic hematuria, mild proteinuria, good prognosis)
• Class III: Focal (hematuria, proteinuria, possible nephrotic syndrome, variable prognosis)
• Class IV: Diffuse (most common, severe nephritis, worst prognosis, requires aggressive treatment)
• Class V: Membranous (nephrotic syndrome, may need immunosuppression)
• Class VI: Advanced sclerosing (end-stage CKD, no immunosuppression recommended)
• Classes I and Il are typically mild and often do not require therapy unless the disease progresses.
• Classes Ill and IV require immunosuppression with glucocorticoids (eg, methylprednisolone, prednisone) and cyclophosphamide or mycophenolate mofetil.
• Class V (membranous) may require immunosuppression if proliferative lesions or nephrotic syndrome is present.
• Class VI is an advanced sclerosing disease, and immunosuppression is not recommended.

Question 4

Which form of lupus nephritis has the worst prognosis?

Answer 4

Diffuse, class IV.

Question 5

What is the standard first-line treatment for Class III & IV lupus nephritis?

Answer 5

• High-dose corticosteroids (e.g., methylprednisolone, prednisone)
• Cyclophosphamide or mycophenolate mofetil (MMF) for immunosuppression
• May patients take hydroxychloroquine to manage their lupus and this medication tends to be well tolerated and not associated with renal dysfunction. The only common side effects include rash and gastrointestinal upset. Hydroxychloroquine-related acute interstitial nephritis is rare and is associated with a predominance of white blood cell casts. Therefore, stopping this medication while managing lupus nephritis is not necessary.

Question 6

What is the role of hydroxychloroquine in lupus nephritis?

Answer 6

Hydroxychloroquine is used for systemic SLE control but is not associated with kidney dysfunction and is not discontinued in lupus nephritis.

Question 7

How is lupus nephritis disease activity monitored?

Answer 7

• Anti-dsDNA antibody titers (correlates with immune complex deposition)
• Serum complement levels (C3, C4) (low levels indicate active disease)
• Proteinuria levels (assesses renal response to therapy)

Question 8

Why is lupus nephritis monitored with anti-dsDNA antibodies?

Answer 8

Renal involvement in systemic lupus erythematosus (SLE) is due to immune complex-mediated glomerular injury. These immune complexes are composed primarily of anti-double stranded DNA (anti-dsDNA) antibodies and are deposited in the mesangial, subendothelial, or subepithelial space, with resultant influx of neutrophils and mononuclear cells. The titers of anti-dsDNA correlate well with the disease activity of lupus nephritis. Of note, anti-dsDNA is also highly specific for SLE.

Question 9

Why is lupus nephritis monitored with complement levels?

Answer 9

Immune complex deposition within the glomerulus induces complement fixation, leading to low circulating complement levels. Complement activation occurs during active disease, so low levels correlate well with disease activity.

Question 10

Why are anti-Smith antibodies not used for monitoring lupus nephritis?

Answer 10

Anti-Smith antibodies remain elevated even when lupus nephritis is inactive, making them useful for diagnosis but not for monitoring disease activity.

Question 11

What are the characteristic urine findings in lupus nephritis?

Answer 11

• Proteinuria (+2 or more on urinalysis, >500 mg/day)
• Hematuria with RBC casts (suggesting glomerular inflammation)
• No WBC casts (unless secondary infection present)

Question 12

Which lupus nephritis class is associated with nephrotic syndrome?

Answer 12

Class V (membranous lupus nephritis) presents with nephrotic-range proteinuria, hypoalbuminemia, and edema.

Question 13

Which lupus nephritis class requires the most aggressive treatment?

Answer 13

Class IV (diffuse lupus nephritis) has the worst prognosis and requires aggressive immunosuppression (steroids + cyclophosphamide or mycophenolate mofetil).

Question 14

Why should renal biopsy be performed BEFORE starting immunosuppression in lupus nephritis?

Answer 14

Biopsy is needed to classify disease severity and guide therapy, preventing unnecessary immunosuppression in cases of mild disease (e.g., Class I, II).