Did you know that around 37 million Americans live with some form of kidney disease? Rare kidney diseases account for a small portion of these cases. A rare disease is defined as one that affects fewer than 200,000 people in the United States. If you’re living with one of 150 rare forms of kidney disease, you may have a hard time finding more information.

This article will cover six facts to know about rare kidney disease. We’ll discuss the types, causes, and symptoms you may experience. We’ll also go over ways doctors diagnose and treat these diseases.

1. There Are Over 150 Rare Kidney Diseases

The 150 rare kidney diseases are far less common than chronic kidney disease (CKD). Both chronic and rare kidney conditions affect how well the kidneys work to filter waste and toxins from the blood. However, rare kidney diseases usually require different diagnostic tests and treatments.

Some forms of rare kidney diseases affect the complement system. The complement system is a complex part of the immune system that acts as the first line of defense against pathogens (bacteria and viruses that can cause disease). Complement 3 glomerulopathy (C3G) develops when the complement 3 (C3) protein is broken down into smaller pieces. These fragments get stuck in the kidneys, leading to inflammation and damage.

Immune complex membranoproliferative glomerulonephritis (IC-MPGN) occurs when the complement system isn’t working properly. In IC-MPGN, abnormal antibodies (immune system proteins) clump together with C3 proteins. They form immune complexes that get stuck in the kidney’s delicate filters (glomeruli). The complexes create inflammation that damages kidney tissues.

Other examples of rare kidney diseases include:

• Immunoglobulin A nephropathy (IgAN) — Leads to antibody buildup in the kidneys
• Polycystic kidney disease (PKD) — Causes fluid-filled sacs or cysts to form in the kidneys
• Alport syndrome — Affects how the kidneys develop and function
• Fabry disease — Causes the buildup of fatty tissue in the kidneys, brain, and heart
• Atypical hemolytic uremic syndrome (aHUS) — Creates blood clots in the kidney’s blood vessels that block blood flow

2. Rare Kidney Diseases Can Have Many Causes

Kidney diseases can develop for many different reasons. CKD usually develops in people with diabetes or high blood pressure. High blood sugar and high blood pressure levels damage the kidneys’ delicate filters over time.

Rare kidney diseases usually have different underlying causes, such as genetic factors or autoimmune disease. Faulty genes with mutations (changes) can affect your kidney function. These genes can be passed down from family members. Examples of genetic kidney diseases include PKD and Alport syndrome.

Diseases like C3G, IC-MPGN, and IgAN occur in people with immune systems that aren’t working properly. Their immune cells mistake their cells for pathogens and attack them. The extra inflammation harms the kidneys.

3. Many Rare Kidney Diseases Share the Same Symptoms

The American Kidney Fund notes that rare kidney disease symptoms vary by condition. It may not be obvious that you have a rare disease. Many kidney conditions share similar symptoms.

The most obvious symptom is any change in your urine’s appearance. Some people have foamy urine caused by extra protein. It can take a few flushes of the toilet for the bubbles to go down. Dark or red urine may be a sign of hematuria — or blood in your urine.

Depending on the type of rare kidney disease, you may make urine that appears more or less normal. People with advanced kidney disease make very little urine and go to the bathroom fewer times throughout the day.

Other symptoms of kidney disease to look out for include:

• High blood pressure
• Swelling or puffiness in your legs, feet, or hands, or around your eyes
• Itchy or dry skin
• Trouble thinking or concentrating
• Dry mouth and changes in your ability to taste

4. It Can Be Challenging To Diagnose Rare Kidney Diseases

Since many kidney diseases share symptoms, doctors have a harder time making the right diagnosis of rare kidney disease. It’s important to work with a nephrologist (kidney specialist) and a rare disease specialist. They have the knowledge and experience to figure out what’s causing your symptoms.

Hypertension (high blood pressure) is common in people with rare kidney diseases. This is because the kidneys regulate your body’s fluid levels. The worse your kidney function is, the more fluid collects. Extra fluid puts more force on your arteries and raises your blood pressure.

Common tests to diagnose kidney diseases include blood and urine tests. Blood tests measure the level of waste products filtered by the kidneys. People with kidney damage have higher levels of these products. You may hear your nephrologist talk about your estimated glomerular filtration rate (eGFR). This test tells you how well your kidneys work.

Urine tests look for abnormal substances in your urine. Healthy kidneys don’t let larger substances pass through the filters. When these filters are damaged, they let blood cells and proteins into your urine. If your nephrologist finds either of these substances in your urine, they’ll order additional tests.

In some cases, the only way to diagnose a rare kidney disease is by taking a biopsy. To conduct this test, a specialist will look at a small piece of kidney tissue under a microscope. Using different techniques, specially trained healthcare providers look for signs of kidney damage in the tissue sample. Biopsies help diagnose certain diseases like C3G and IC-MPGN.

Blood tests can also confirm certain genetic kidney diseases like Alport syndrome and polycystic kidney disease. If you have a family history of rare kidney disease, your nephrologist may order genetic testing. They’ll send a small blood or saliva sample to a lab to look for specific gene mutations (changes).

5. Researchers Are Studying New Treatments for Rare Kidney Diseases

Unfortunately, many rare kidney diseases don’t have a treatment that has been approved by the U.S. Food and Drug Administration (FDA). A handful of medications have recently been approved for IgAN. They include sparsentan (Filspari) and iptacopan (Fabhalta). Some of these medications are being studied as possible treatments for other rare kidney diseases.

Doctors usually treat rare kidney diseases by treating the symptoms. The goal is to preserve your kidney function and slow disease progression. Some people with rare kidney disease eventually develop kidney failure. At this point, treatment options usually include dialysis or a kidney transplant.

Managing a rare disease can be a challenge, especially if your doctor isn’t familiar with it. Don’t be afraid to get a second opinion and advocate for your treatment. Consider making a list of questions or topics to discuss with your doctor before your appointments.

6. Living With a Rare Kidney Disease Can Affect Your Mental Health

Rare, chronic diseases can be exhausting to live with. Many people with rare kidney diseases have to manage mental health conditions as well. Anxiety, depression, and stress all take their toll on your physical and emotional well-being.

Mental health conditions can develop in response to changes as you navigate living with kidney disease. Common stressors include:

• Managing new treatments, like dialysis
• Costs of treatment
• Worrying about how your disease affects your family and social life
• Lack of sleep

Health experts recommend making time to focus on your emotional wellness after a kidney disease diagnosis. Participating in hobbies or taking time out of your day for meditation can help with the new stress of your diagnosis. Connecting with others through a support group creates a sense of belonging and provides emotional support. It’s also important to seek professional help as needed.

Talk With Others Who Understand

On MyKidneyDiseaseTeam, people with kidney disease and their loved ones come together to ask questions, give advice, and share their stories with others who understand life with kidney disease.

Are you living with a rare kidney disease? Do you have other questions about your condition? Share them in the comments below, or start a conversation by posting on your Activities page.