Lupus nephritis is an autoimmune disease that causes rampant inflammation throughout the body. It can affect the skin, bones, muscles and/or internal organs, including the heart, brain and kidneys. Kidney inflammation can be a sign of severe illness that indicates a need for aggressive treatment, says Yale Medicine pathologist Gilbert Moeckel, MD, PhD. Lupus nephritis (also called lupus kidney disease) is the diagnosis for lupus that has attacked the kidneys. 

As an autoimmune disease, lupus puts the immune system in overdrive. The immune system aggressively attacks healthy cells as though they were a foreign threat, causing a wide range of potential symptoms, such as rashes, fatigue, joint pain and fevers.

A diagnosis of lupus nephritis is a sign that lupus is advancing at a dangerous pace, Dr. Moeckel says. “Lupus nephritis is very aggressive and it can rapidly lead to end-stage renal (kidney) disease,” he says.

The kidney biopsy is the “gold standard for the diagnosis of lupus nephritis," Dr. Moeckel says. Though lupus causes uncomfortable and debilitating symptoms, many people live a long time with the disease. But when the inflammation spreads to the kidneys, it is a sign that the disease is accelerating and becoming more destructive. The degree of disease activity correlates with the amount of inflammation in the kidney, Dr. Moeckel adds.

“A patient with complete failure of kidney function requires dialysis, which can have its own set of complications,” he says. “That’s why the kidney biopsy is crucial in assessing the stage of the disease in order to treat adequately and prevent complete loss of renal function.”

If lupus nephritis is suspected, doctors will order a kidney biopsy, which can be performed on an outpatient basis. Under ultrasound guidance and using local anesthesia, a biopsy is taken using a very thin needle that is inserted into the kidney tissue. The specimen is sent immediately to the pathology lab for further processing. The tissue will undergo many tests to determine the presence and extent of the immune-mediated injury by lupus.

Lupus has a wide range of symptoms, many of which mimic other conditions. As with other autoimmune diseases, diagnosis can be tricky.

“The clinician can look at a patient’s symptoms and laboratory tests and say, ‘I think this patient has lupus nephritis,’ but the kidney biopsy, which is the definitive test, is done in the pathology department,” Dr. Moeckel says. 

The pathologists in Yale Medicine’s renal pathology lab use advanced techniques and technology, including immunofluorescence and electron microscopy (highly specialized and powerful types of microscopes), to study the kidney tissue samples of patients with lupus nephritis.

“We are looking for some very specific findings, such as crescent-shaped cell proliferation and inflammation of the small and large vessels, which is a sign of vascular involvement,” Dr. Moeckel

The findings are then given a designated type and activity grade that reflects how aggressively the disease has attacked the kidney. “The accurate type and grade is conveyed to the clinician, who then uses this information to determine how to treat a particular patient’s lupus-related kidney disease.”

"We have a longstanding research tradition, with more than four decades of history in the diagnosis and treatment of lupus kidney disease,” Dr. Moeckel says. “This gives us a great deal of experience and a large repository of previous cases, giving us the opportunity to study and compare tens of thousands of kidney biopsies with lupus nephritis.”

Electron microscopy, by which a powerful microscope uses electron beams to produce higher and finer magnification, is an important advantage that the Yale Medicine Department of Pathology has over other local hospitals and physician practices.

“This allows us to perform very detailed tests that nobody else is able to do,” Dr. Moeckel says. “And it’s not only that we have very expensive and powerful technology, we also have very capable and experienced people who are using it. Used correctly, the electron microscope can be extremely valuable in that it makes difficult diagnoses possible.”