Lupus and Kidney Disease: What You Should Know about Lupus Nephritis (Lupus Kidney Disease)

Introduction

At this session of the SLE Workshop at HSS, Dr. Kyriakos Kirou presented his expertise on the diagnosis, symptoms, treatments, and research related to lupus and kidney involvement, including lupus nephritis (LN). Dr. Kirou is an assistant attending physician at HSS’s new lupus clinic.

When presenting, Dr. Kirou emphasized that the purpose of his presentation is to educate patients about lupus and its interaction with the kidney and should not be used as therapeutic advice. He stressed that when patients need to make a decision about their own specific care, they should consult their own rheumatologist. It is important to recognize that there’s no “one fits all” therapy.

Dr. Kirou focused on identifying how lupus can affect the kidney, causing LN. He also described the process of looking at measurements, kidney tests, other important tests to diagnose LN, and spoke about the necessary lifestyle changes LN patients may have to adopt after their diagnosis.

First, it is important to understand how the kidney functions, what happens when someone with lupus has problems with their kidneys, and how they can go about dealing with the situation.

Background Information

Lupus:
Lupus is a chronic and autoimmune disease that affects several parts of the body, including joints, blood, skin, and kidneys. The immune system of those with lupus does not function properly. Lupus creates autoantibodies that fight and damage the cells, tissues, and body organs. When they are present, they can likely lead to disease.

For a more involved discussion about lupus, please refer to our In-Depth Overview of Systemic Lupus Erythematosus.

Kidney:
The kidney is a bean-shaped, fist-sized organ that helps cleans the body from any toxic or other waste products. Not only that, the kidney plays an important role in helping to maintain one’s blood pressure, the volume of our body fluids, the ratio of water in our bodies, and our PH balance. We have two kidneys, but one healthy one is all we need. However, throughout time, we start to lose some of our kidney function.

Lupus Nephritis

Lupus Nephritis is a type of disease that involves lupus and the kidney. This occurs when autoantibodies and other antigens are deposited in the kidney due to blood circulation issues, causing kidney inflammation. 30-50% of lupus patients will develop LN within the first six months to three years of being diagnosed with SLE. Many patients with LN can have protein in their urine (proteinuria), but these patients may not always experience problems or have renal disease.

Inflammation of the kidney prevents it from functioning normally and can cause it to spill protein, which causes frothy and/or bloody urine. Other early manifestations of lupus nephritis include swelling of the feet and a general increase in blood pressure. These symptoms are usually seen as the first signs of the disease.

Signs of LN may include:

• Swelling or puffiness of feet, legs, eyes
• High blood pressure
• Frothy urine or getting up constantly to urinate at night
• Blood in urine

One may not experience any symptoms, however, so a urine test is needed. It’s crucial to have your doctor rule out other causes such as kidney stones or a urinary infection before considering the diagnosis of LN.

Lupus Nephritis Classification:

Class 1: Minimal Mesangial Lupus nephritis (LN)
Class 2: Mesangial Proliferative LN
Class 3: Focal LN
Class 4: Diffuse LN
Class 5: Membranous LN
Class 6: Advanced Sclerosing LN

Kidney biopsy is crucial to help diagnose lupus nephritis and rule out other issues. It’s also helpful to identify the classification of LN to determine which therapy is effective. A biopsy is performed whenever there’s an indication of a severe form of nephritis (Class 3-5). At times, a biopsy needs to be repeated to confirm a diagnosis.

Testing for Lupus Nephritis

There is a wide range of tests that can determine how the kidney is affected.

1. Blood: BUN (normally<20) and creatinine (Cr; normally <1 in average woman; it may be higher in muscular men as it reflects muscle mass). Also albumin (normal>3.5) which may be decreased due to loss of protein in the urine.
2. Electrolytes: sodium, potassium, bicarbonate
3. Creatinine clearance: Calculated by using creatinine, age, race, gender. Normally 80-120 ml/min/1.73m2
4. Urine analysis: Normally 0-trace protein, no red and white blood cells (<5 RBC, <5 WBC)
5. 24-h urine protein: (creatinine is also measured to assess whether collection was performed properly): normally <300mg/24h. In lupus by definition>500
6. Spot urine protein/creatinine ratio: Normally <300 mg/24h. It may vary depending on the timing of collection: best to test second urine of the day
7. Renal ultrasound: size of kidneys and consistency of kidney tissue
8. Kidney biopsy

Other Important Tests:

1. Serology:

1. C3 (normally>80), when disease is active it is usually low
2. C4 (normally>18), when disease is active it is usually low
3. Anti-dsDNA (normal is 0), when disease is active it is usually high
4. Antiphospolipid antibodies (anticardiolipin antibodies IgG, IgM, IgA, and lupus anticoagulant). This might determine whether blood thinners are needed
   

2. Bone test

1. Blood level of 25-OH-Vitamin D (normal >30)
2. Blood level of intact parathyroid hormone (iPTH; high in advanced liver disease)
3. Bone mineral density test (to check for osteoporosis)

3. Fasting lipids: High in nephritic syndrome

4. Fasting blood sugar: Diabetes or other complications of steroids

5. Hemoglobin (HB): Anemia might be due to the inflammation, blood loss, hemolysis or advanced kidney disease.

6. White blood cells: Low due to the disease or therapy. Increased risk of infection.

7. Platelets (PLT): Low due to the disease or therapy. Increased risk of bleeding.

8. Purified protein derivative (PPD) test for latent tuberculosis (TB)

9. Hepatitis C, Hepatitis B, HIV

The best prevention for kidney issues is to create lifestyle changes. These changes include:

• Being hydrated
• Maintaining a low sodium intake, especially if one has hypertension
• Maintaining a low potassium intake, low phosphorus, low protein
• Don’t smoke or drink alcohol
• Exercise
• Maintain your blood pressure and weight
• Avoid nephrotoxic agents such as NSAIDS (Advil, Aleve) and so forth.

Conclusion

Important factors to consider:

• Be active in your healthcare and partner with your rheumatologists.
• Understand the role of your nephrologists (doctors who specialize in kidneys) and how he or she can help you understand any kidney-related issue that may arise.
• Pick the best therapeutic agent with your rheumatologist.
• Be aware of what pills you’re taking, their dosage, and when to take them.
• Recognize the different signs of flares relating to the disease such as headache, high blood pressure, discolored urine, fever, joint pains, skin rash, shortness of breath, and foot/eye swelling.
• Recognize the signs of therapy-adverse events such as fever, chills, sore throat, cough, shortness of breath, blood in urine, and diarrhea.
• Do not ignore your bone health (having enough calcium/vitamin D) or cardiovascular health (i.e., not smoking).

Even with all the information provided, patients should make their decision closely with their rheumatologist and nephrologist to find the best therapy and health care that best fits their needs.