AJMC Insights: Lupus Nephritis - Episode 2
Ellen Ginzler, MD, MPH, and German Hernandez, MD, FASN, FACP, provide insight into the clinical presentation of patients with lupus nephritis, the progression of systemic lupus erythematosus to lupus nephritis, and the prevalence of this rare disease.
Ellen Ginzler, MD, MPH: Lupus nephritis usually presents to the rheumatologist, especially if there’s joint involvement. Because anemia and fatigue may be significant early symptoms, someone who hasn’t been diagnosed may go to a primary care physician because they have nonspecific symptoms or fever, weight loss, or lack of appetite. Through routine laboratory testing or a physical exam by the physician, some of the autoimmune and multisystem features may show up. It’s much less common for the patient to present with very active lupus nephritis or lupus kidney involvement that’s so symptomatic that they would immediately go to a nephrologist. But that may happen occasionally, especially when it develops very rapidly and there’s a rapid loss of kidney function.
German Hernandez, MD, FASN, FACP: In my practice, I often find that a patient has already had a diagnosis of lupus, and they’re being followed by a rheumatologist. The rheumatologist will pick up that there’s protein or blood in the urine, and that will prompt the referral to be evaluated by us, the nephrologist. Or if a patient doesn’t have active continued medical care, they can present with swelling of their legs. That’s 1 of the main types of presentations that people have with lupus nephritis. They can also be referred to us without a known diagnosis of lupus if they’re seeing their family doctor and they’re found to have blood or protein in the urine.
A lot of times, we get patients who haven’t necessarily had a lupus diagnosis, and while we’re doing the work-up for these urinary abnormalities, we find that they have both lupus and lupus nephritis at the same time. A lot of patients come to us from the rheumatologist if they already have a diagnosis of lupus, or from their general practitioner if they don’t. They could also be coming to the emergency department when they show up with more advanced symptomatology, such as swelling in their legs.
Ellen Ginzler, MD, MPH: One of the typical things about lupus is that many of the features that are going to be active throughout a patient’s course develop within the first 2 to 3 years. When we diagnose a patient with lupus, we always look carefully to see if there are signs of lupus nephritis or lupus kidney involvement. We look for abnormal protein in the urine. We look for red blood cells in the urine. We’ll look for evidence that the kidneys are not functioning normally. If there’s a lot of protein being excreted in the urine, you tend to hold on to fluid, so patients will have leg edema, or swelling in their legs, which may be a sign. Another sign that the kidneys may be involved is the development of high blood pressure. Symptoms related to high blood pressure may give a hint that someone has active lupus. The best way to make that diagnosis is by physical examination and starting off with routine laboratory tests. Then there are special antibody tests we do to identify whether there’s active kidney disease.
German Hernandez, MD, FASN, FACP: How often patients with lupus progress to lupus nephritis can vary depending on the different populations. It can be as low as 15% or as high as 45% of patients with lupus. Certain racial and ethnic minority groups tend to have a higher burden of lupus nephritis, but in general, about 40% to 45% of patients with lupus can have involvement with lupus nephritis.
Ellen Ginzler, MD, MPH: There’s some disagreement about how common lupus is in the United States. It may depend on whether you use a strict definition based on criteria. There are now several sets of criteria. The American College of Rheumatology has a set of criteria. An organization called SLICC, or the Systemic Lupus International Collaborating Clinics, has another set of criteria. There’s a lot of overlap between them.
It also depends on what your purpose is in determining how much lupus exists. If you want to understand lupus in terms of what causes it, you want a strict definition. If you want to look at the burden on health care or the patient, you may broaden that. Organizations like the Lupus Foundation of America will give you a figure of over a million cases of lupus in the United States. But other studies that use more strict definitions and careful attention to how the diagnosis is made will more likely come up with a figure of 300,000 to 350,000 cases of lupus in the United States. That would mean that the prevalence of lupus nephritis is probably in the neighborhood of under 200,000 at any time, making it an orphan disease. That also depends upon geographic distribution. There seems to be more lupus and lupus nephritis in urban areas, or areas where patients are less economically advantaged. It’s more common in individuals of color. It’s much more common in Black, Hispanic, and even Asian individuals than in Caucasians.
Transcript edited for clarity.