What You Need to Know About Lupus' Effect on the Kidneys

Systemic Lupus Erythematosus (SLE) can have bad consequences for your kidneys

What is Systemic Lupus Erythematosus (SLE)?

SLE, or lupus as it's commonly known, is an autoimmune disease.  It is an entity that we still haven't clearly fully understood.  We do know however that for some reason, the body's immune system starts to act against the body's own tissues.  Your immune machinery loses the ability to differentiate between friend and foe.  Your body essentially comes under "friendly fire".

Does lupus affect the kidneys?

Yes.  The catch-all umbrella term for the disease when lupus affects the kidney is called lupus nephritis.  It can range from a relatively benign presentation (where the only problems that a patient might have could be the presence of small amount of protein in the urine or a little bit of high blood pressure), to full blown rapid decline in kidney function towards complete kidney failure where dialysis or kidney transplantation might become necessary for survival.

If you have lupus, how do you know if the kidneys are being affected or not?

Any significant damage by lupus to the kidneys will be associated with certain symptoms or signs. These could be:

  • Elevation in blood pressure
  • Presence of foam or suds in the urine (due to presence of high amount of protein). 
  • Blood in the urine
  • Swelling, usually in the ankles but could be present at other locations including around the eyes, and in the hands
  • All the above could be present with the other usual features of lupus like rash and joint pain.

Which lab tests can be done to confirm if lupus is damaging your kidney?

The typical lab test done would include the general tests of kidney function first.  These have been covered in detail here.  Let me give you an overview:

  • Blood test of kidney function to look at your serum creatinine level and GFR
  • Urine tests to look for blood in the urine
  • Urine tests to assess the presence of protein in the urine and if present, measure its amount
  • Kidney biopsy.  If there is reasonable suspicion to believe that lupus might be affecting the kidney, a kidney biopsy is highly warranted.  That is because it really is the only confirmatory test to really prove that lupus is indeed damaging the kidney.  Even if we do know that lupus is the reason for kidney damage, it still makes sense to do the kidney biopsy because lupus' effect on the kidney could range from mild disease (requiring no more than a blood pressure medication called ace inhibitors or angiotensin blockers), to the worst case scenario where severe kidney damage associated with severe inflammation in the kidney might be visible.  This in turn helps in fine-tuning the treatment of lupus nephritis in the afflicted person.

What can a patient with confirmed lupus nephritis expect?

A patient with biopsy-proven lupus nephritis will not necessarily decline to the point of needing dialysis.  Some patients do, some don't.  The astute nephrologist should be able to predict which patient is more likely to be high risk.

 Clinical predictors that help with this assessment include the degree to which your kidney function or GFR has been lowered, and the extent of inflammation and damage seen in the kidney on kidney biopsy tests.  Patients with these features might be high risk and need to aggressively treated.

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