Lupus nephritis is a kidney disorder that is a complication of systemic lupus erythematosus.

Lupus nephritis occurs when antibodies (antinuclear antibody and others) and complement build up in the kidneys, causing inflammation. It often causes nephrotic syndrome (excessive protein excretion) and may progress rapidly to renal failure. Nitrogen waste products build up in the bloodstream.

Systemic lupus erythematosus (SLE) causes various disorders of the internal structures of the kidney, including interstitial nephritis and membranous GN. Lupus nephritis affects approximately 3 out of 10,000 people. In children with SLE, about half will have some form or degree of kidney involvement.

SLE is most common in women 20-40 years old. For more information, see the general article on systemic lupus erythematosus.

Symptoms of lupus nephritis include:

• Blood in the urine
• Foamy appearance to urine
• High blood pressure
• Swelling of any area of the body

For general lupus symptoms, see the article on SLE.

A physical exam shows signs of decreased kidney functioning with edema. Blood pressure may be high. Abnormal sounds may be heard when the doctor listens to the heart and lungs, indicating fluid overload.

Lupus nephritis is usually discovered during investigation of the causes of reduced kidney function. Fewer than half of patients have other symptoms of SLE at the time of diagnosis of lupus nephritis.

Tests that may be done include:

• ANA titer
• BUN and creatinine
• Lupus test
• Urinalysis
• Urine immunoglobulin light chain

A kidney biopsy is not used to diagnose lupus nephritis, but to determine what treatment is appropriate.

• Complement component 3
• Complement
• Syphilis test - may be falsely positive