Lupus nephritis

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Lupus nephritis
Classification and external resources
Diffuse proliferative lupus nephritis - high mag.jpg
Micrograph of diffuse proliferative lupus nephritis showing increased mesangial matrix and mesangial hypercellularity. Kidney biopsy. PAS stain.
ICD-10 M32.1+N08.5*
ICD-9 583.81
MedlinePlus 000481
eMedicine med/1597
MeSH D008181

Lupus nephritis is an inflammation of the kidney caused by systemic lupus erythematosus (SLE), a disease of the immune system. Apart from the kidneys, SLE can also damage the skin, joints, nervous system and virtually any organ or system in the body.

Signs and symptoms[edit]

General symptoms of lupus include malar rash, discoid rash, photosensitivity, oral ulcers, nonerosive arthritis, pleuropericarditis, renal disease, neurological manifestations, and haematological disorders.

Clinically, SLE usually presents with fever, weight loss (100%), arthralgias, synovitis, arthritis (95%), pleuritis, pericarditis (80%), malar facial rash, photodermatosis, alopecia (75%), anaemia, leukopaenia, thrombocytopaenia, and thromboses (50%).

About half of cases of SLE demonstrate signs of lupus nephritis at one time or another. Renal-specific signs include proteinuria (100%), nephrotic syndrome (55%), granular casts (30%), red cell casts (10%), microhematuria (80%), macrohematuria (2%), reduced renal function (60%), RPGN (30%), ARF (2%), hypertension (35%), hyperkalemia (15%) and tubular abnormalities (70%).

A diagram of the pathological changes in a glomerulus visible via electron microscopy in SLE nephritis. Black: immune complex; dark purple: basement membrane; pink: endothelium; green: visceral epithelium; light purple: mesangial cells

In histology, stage I (minimal mesangial) disease has a normal appearance under light microscopy, but mesangial deposits are visible under electron microscopy. At this stage urinalysis is typically normal.

stage II disease (mesangial proliferative) is noted by mesangial hypercellularity and matrix expansion. Microscopic haematuria with or without proteinuria may be seen. Hypertension, nephrotic syndrome, and acute renal insufficiency are rare at this stage.

stage III disease (focal lupus nephritis) is indicated by sclerotic lesions involving less than 50% of the glomeruli, which can be segmental or global, and active or chronic, with endocapillary or extracapillary proliferative lesions. Under electron microscopy, subendothelial deposits are noted, and some mesangial changes may be present. Immunofluorescence reveals the so-called "Full House" stain, staining positively for IgG, IgA, IgM, C3, and C1q. Clinically, haematuria and proteinuria is present, with or without nephrotic syndrome, hypertension, and elevated serum creatinine.

Diffuse proliferative lupus nephritis; photo shows the classic "flea-bitten" appearance of the cortical surface in the diffuse proliferative glomerulonephritides

stage IV lupus nephritis (diffuse proliferative) is both the most severe, and the most common subtype. More than 50% of glomeruli are involved. Lesions can be segmental or global, and active or chronic, with endocapillary or extracapillary proliferative lesions. Under electron microscopy, subendothelial deposits are noted, and some mesangial changes may be present. Immunofluorescence reveals the so-called "Full House" stain, staining positively for IgG, IgA, IgM, C3, and C1q. Clinically, haematuria and proteinuria are present, frequently with nephrotic syndrome, hypertension, hypocomplementemia, elevated anti-dsDNA titres and elevated serum creatinine.

A wire-loop lesion may be present in stage III and IV. This is a glomerular capillary loop with subendothelial immune complex deposition that is circumferential around the loop. Stage V is denoted by a uniformly thickened, eosinophilic basement membrane. Stage III and IV are differentiated only by the number of glomeruli involved (which is subject to inherent sample bias), but clinically the presentation and prognosis are both expected to be more severe in stage IV versus stage III.

Stage V (membranous lupus nephritis) is characterized by diffuse thickening of the glomerular capillary wall (segmentally or globally), with diffuse membrane thickening, and subepithelial deposits seen under electron microscopy. Clinically, stage V presents with signs of nephrotic syndrome. Microscopic haematuria and hypertension may also been seen. Plasma creatinine is usually normal or slightly elevated, and stage V may not present with any other clinical/serological manifestations of SLE (complement levels may be normal; anti-DNA Ab may not be detectable). Stage V also predisposes the affected individual to thrombotic complications such as renal vein thromboses or pulmonary emboli.

A final stage is usually included by most practitioners, stage VI, or advanced sclerosing lupus nephritis. It is represented by Global sclerosis involving more than 90% of glomeruli, and represents healing of prior inflammatory injury. Active glomerulonephritis is usually not present. This stage is characterised by slowly progressive renal dysfunction, with relatively bland urine sediment. Response to immunotherapy is usually poor.

A tubuloreticular inclusion is also characteristic of lupus nephritis, and can be seen under electron microscopy in all stages. It is not diagnostic however, as it exists in other conditions. It is thought to be due to chronic interferon exposure.

Diagnosis[edit]

The diagnosis of lupus nephritis depends on blood tests, urinalysis, X-rays, ultrasound scans of the kidneys, and a kidney biopsy. On urinalysis, a nephritic picture is found and RBC casts, RBCs and protenuria is found.

The World Health Organization has divided lupus nephritis into five stages based on the biopsy. This classification was defined in 1982 and revised in 1995.[1]

  • Class I is minimal mesangial glomerulonephritis which is histologically normal on light microscopy but with mesangial deposits on electron microscopy. It constitutes about 5% of cases of lupus nephritis.[2] Renal failure is very rare in this form.[2]
  • Class II is based on a finding of mesangial proliferative lupus nephritis. This form typically responds completely to treatment with corticosteroids. It constitutes about 20% of cases.[2] Renal failure is rare in this form.[2]
  • Class III is focal proliferative nephritis and often successfully responds to treatment with high doses of corticosteroids. It constitutes about 25% of cases.[2] Renal failure is uncommon in this form.[2]
  • Class IV is diffuse proliferative nephritis. This form is mainly treated with corticosteroids and immunosuppressant drugs. It constitutes about 40% of cases.[2] Renal failure is common in this form.[2]
  • Class V is membranous nephritis and is characterized by extreme edema and protein loss. It constitutes about 10% of cases.[2] Renal failure is uncommon in this form.[2]

Medicines are prescribed that decrease swelling, lower blood pressure, and decrease inflammation by suppressing the immune system: Patients may need to monitor intake of protein, sodium, and potassium. Patients with severe disease should restrict their sodium intake to 2 grams per day and limit fluid as well. Depending on the histology, renal function and degree of proteinuria, patients may require steroid therapy or chemotherapy regimens such as cyclophosphamide, azathioprine, mycophenolate mofetil, or cyclosporine.

Treatment[edit]

Drug regimens prescribed for lupus nephritis include mycophenolate mofetil (MMF), intravenous cyclophosphamide with corticosteroids, and the immune suppressant azathioprine with corticosteroids. MMF and cyclophosphamide with corticosteroids are equally effective in achieving remission of the disease. MMF is safer than cyclophosphamide with corticosteroids, with less chance of causing ovarian failure, immune problems or hair loss. It also works better than azathioprine with corticosteroids for maintenance therapy.[3]

References[edit]

  1. ^ Weening JJ, D'Agati VD, Schwartz MM, et al. (February 2004). "The classification of glomerulonephritis in systemic lupus erythematosus revisited". J. Am. Soc. Nephrol. 15 (2): 241–50. doi:10.1097/01.ASN.0000108969.21691.5D. PMID 14747370. 
  2. ^ a b c d e f g h i j Table 6-4 in: Elizabeth D Agabegi; Agabegi, Steven S. (2008). Step-Up to Medicine (Step-Up Series). Hagerstwon, MD: Lippincott Williams & Wilkins. ISBN 0-7817-7153-6. 
  3. ^ Henderson, L.; Masson, P.; Craig, JC.; Flanc, RS.; Roberts, MA.; Strippoli, GF.; Webster, AC. (2012). "Treatment for lupus nephritis.". Cochrane Database Syst Rev 12: CD002922. doi:10.1002/14651858.CD002922.pub3. PMID 23235592. 

External links[edit]