Medullary Kidney Disease

Mucin-1 Kidney Disease Frequently Asked Questions

What is Mucin-1 Kidney Disease?

Mucin-1 Kidney Disease (MKD), previously known as Medullary Cystic Kidney Disease Type I (MCKD1), is a rare inherited kidney disease that causes progressive kidney failure leading to the need for a kidney transplant or dialysis in most patients.

Why was it called Medullary Cystic Kidney Disease Type 1?

“Medullary” means the middle of the kidney, and cysts are small holes.  It was initially thought that in this disease there were small holes (cysts) formed in the middle of the kidney.  However, most patients with MKD do not have cysts in the middle of their kidney, or in other parts of their kidney.  For this reason, the name used for this condition is incorrect.  Unfortunately, doctors have used this name for many years, and it is hard to change names.

It was called Type 1 because there are two similar types of this disease.  It turns out that the two types of the disease are entirely unrelated.  

How frequent is MKD?

MKD is considered a rare disease.  There are about 200 families worldwide that have been identified with this disease.

What do the kidneys do?

The kidneys are bean-shaped organs, about the size of a fist.  They are located in the back next to the spinal column.

Healthy kidneys filter and clean about 200 quarts (liters) of blood every day, removing excess water, minerals, and wastes.

The kidneys also produce hormones that make red blood cells and control blood pressure.  They make active Vitamin D, which the body uses to keep your bones strong.

What happens if you have MKD?

In MKD, patients slowly lose kidney function over time. 

Kidney failure is usually determined by a blood test, called the blood creatinine level.  Creatinine is a waste product that your muscles produce as they work.  Healthy kidneys will filter creatinine into the urine, while damaged ones will not.  Because damaged kidneys cannot filter creatinine well, it stays in the bloodstream and the blood creatinine level rises.

Blood creatinine is part of a group of tests that may be done as part of a routine physical or before surgery.  MKD may be first identified when an elevated creatinine is found on a routine blood test like this.

In MKD, blood creatinine levels rise slowly over years as the kidneys become more damaged.  Once the levels rise to a certain level, usually above about 6 mg/dL (milligrams per deciliter) or about 500 mmol/L (millimoles per liter), the patient must begin dialysis or have a kidney transplant.

At what age is dialysis or kidney transplantation needed?

In some families, all affected persons needing kidney replacement (this means a kidney transplant or dialysis) before 40 years of age.  In other families, age can be quite different for different persons, with some needing dialysis in their 20’s while others are still not on dialysis in their 60’s.

Why is a kidney transplant the only cure for MKD?

If someone has MKD, their kidneys make an abnormal protein, and this abnormal protein gets trapped within their kidney cells.  When a kidney transplant is done, the transplanted kidney is normal and does not make the abnormal protein.  Therefore the transplanted kidney is normal and the disease will not develop in it.

How will MKD make me feel?

Many people do not even know they have a kidney disease until their blood creatinine levels rise very high and they lose a lot of kidney function.  They usually do not develop any symptoms until the disease is very advanced.  They then become more tired than usual and just start to not feel so good.  Their appetite may worsen.  When kidney disease gets worse, patients like to keep the room warmer than usual.  They often develop anemia.

My doctor told me that I have MKD.  About what age will my kidneys fail to the point I need dialysis?

There is a lot of variation as to the age when patients will need treatment for kidney failure.  In some families, patients need dialysis in their 20’s and 30’s, while in others, they do not need it until their 60’s and maybe even later.  Even within families, some patients go on dialysis earlier or later than their parents or siblings.  We do not know why some patients go on dialysis earlier or later than patients in other families.

How does having MKD affect my health over the course of my life?

It is important to know that people with kidney disease feel fine and have no health effects until they lose half of their kidney function.  At that time, patients may start having high blood pressure and anemia.  The anemia can make them feel tired, but in general patients still feel normal.

When patients have lost about 2/3 of their kidney function they begin to feel more tired and may develop a decreased appetite. 

When 90% of kidney function is lost, patients feel tired and have nausea and usually need a kidney transplant or dialysis.

From this you can see that most of the kidney function has to be lost before any symptoms are noticed.  Even then, the symptoms are usually quite mild for a long period of time.

If most members of your family go on dialysis before they are 30, you will likely feel totally normal throughout your teenage years and have no problems.  You may develop mild high blood pressure.  Into your twenties, you will slowly develop worsening kidney function and feel not quite so good.  Over time, you will have worse high blood pressure and anemia.  You may need shots to keep your blood count up.  Eventually, you will develop more fatigue and less appetite and will need a kidney transplant or dialysis.

If family members go on dialysis later in life, you will likely feel totally normal into your 30’s and 40’s.  Some individuals do not develop advanced kidney failure even into their 60’s.

Can a urine test be used to diagnose MKD?

In many types of kidney disease there is blood and protein in the urine.  However, in MKD there is very little protein or blood in the urine.  For this reason, routine urine tests your doctor might order are not good to diagnose MKD.

Can I prevent MKD?

Unfortunately there is no way to prevent MKD.

Where can I get tested to find out if I have MKD?

Please contact Dr. Anthony Bleyer at kidney@wakehealth.edu or (336)716-4513 if you are interested in genetic testing.

What can I do for my health if I have MKD?

Currently there is no known treatment for MKD, and the only cure is a kidney transplant.  However, there is still a lot that you can do to stay healthy if you have MKD:

  1. Do not smoke.  Smoking makes every type of kidney disease get worse more quickly.  It also causes hardening of the arteries and lung disease.  The combination of kidney disease and smoking is not good.  Thus, it is important to stop smoking if you do smoke.  Children of affected MKD patients should be encouraged to never start smoking.
  2. Check blood pressure regularly.  As kidney disease worsens, blood pressure can increase.  This rise in blood pressure can lead to a higher risk of heart disease, strokes and heart attacks.  If your blood pressure is high, you should get it treated.  You should work with your doctor to keep it under good control.
  3. Stay in shape and keep weight under control.  Being very overweight can make it more difficult to do the surgery for a kidney transplant.  You should watch your weight closely.

What kind of diet should I eat if I have MKD?

When kidney disease is mild you should eat the same heart healthy diet that is recommended for the general population.  A low sodium diet with less meat protein may be good for your health overall.  It is not known if such a diet will slow the rate of kidney disease.  Before significant kidney damage has occurred, MKD patients should have the same heart healthy diet as individuals who do not have MKD.

What about vitamins and processed sugars or an all natural diet to help with MKD?

Natural diets, extreme diets, and all natural vitamins are recommended for almost every disease.  There is no evidence that any of these treatments work for kidney disease, and especially no evidence that they are good for MKD.  The heart healthy diet that we all should eat is the diet of choice for MKD patients without significant kidney failure.

What about MKD research?

Now that the gene for MKD has been found, a lot of research is being done on this condition.  Since there are so few patients with this disease, every patient with the disease who takes part in research provides helpful information.  Participating in MKD research trials is also likely to be helpful.  Please contact Dr. Anthony Bleyer at kidney@wakehealth.edu or 336-716-4513 if you are interested.

Why is MKD research important?

The goal of our research is to find a cure for MKD.  This is our only goal.  To find a cure, we will need to study more on how the abnormal MUC1 protein causes disease, and we need to study MUC1 production in affected persons and compare it with persons who are unaffected.



Last Updated: 04-06-2015
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