Excessive protein in the urine: think nephrotic syndrome

When you have excessive protein in the urine, you get a cluster of symptoms that is medically known as nephrotic syndrome. You can have protein in the urine in many different conditions, but when the protein is in an excessive amount, it is always nephrotic syndrome. In my 15 years of experience taking care of hospitalized patients, I have treated several people with truly excessive amounts of protein in their urine.

Nephrotic syndrome is relatively uncommon, and many doctors may not have actually treated someone with it. Based on a recent estimate, truly excessive protein levels in the urine occur in only 3 out of 100,000 adults in the United States. You need to be able to immediately think about nephrotic syndrome whenever anyone has an excessive amount of protein in their urine. Unfortunately, the diagnosis of nephrotic syndrome is delayed because not many people, even doctors, make the immediate connection between excessive amounts of protein and nephrotic syndrome.

In this article, I will teach you everything you need to know about nephrotic syndrome based on my personal experience as well as a review of relevant medical literature.

After reading this article, you will understand:

  1. What are the three distinguishing features of nephrotic syndrome?
  2. How much protein in the urine is considered excessive, and why it is important to make that distinction?
  3. How excessive protein in the urine leads to other symptoms of nephrotic syndrome
  4. What to expect if diagnosed with nephrotic syndrome

What are the three distinguishing features of nephrotic syndrome?

Here are the distinguishing features of nephrotic syndrome:

  • Excessive protein in the urine
  • Excessive swelling all over the body
  • Very high blood cholesterol

How much protein in the urine is considered excessive, and why?

More than 3.5 grams of protein in the urine per day is considered excessive.

What is so special about losing 3.5 grams of protein every day?

That is the amount of protein lost when we know it is nephrotic syndrome. You can have protein in the urine from many different causes. However, nephrotic syndrome is the only condition that can result in this much protein in the urine.

The method of losing excessive amounts of protein due to nephrotic syndrome is fundamentally different from all other types of protein loss. To understand the difference, you need to imagine protein squeezing out of microscopic holes in your kidney filters. In essence, kidneys make up the filtration system of our blood.

A diagram showing a kidney with a leaky filter causing excessive protein in the urine
A leaky kidney filter with nephrotic syndrome leads to excessive protein in the urine

In all other causes of protein loss, you can imagine smaller holes in the filter. The only proteins that spill out are the proteins small enough to squeeze out. Only proteins whose molecules are smaller than a certain size end up in the urine. This type of protein loss is selective. Important proteins that are heavier with bigger molecules are preserved. There are only so many small-sized proteins in the blood. Even when all the smaller proteins leak out, they won’t amount to 3.5 grams a day.

When you have excessive protein in the urine, all kinds of proteins leak out. The holes are large enough to let any protein through, even the important heavy proteins with bigger molecules. When you measure the amount of protein in the urine and it is more than 3.5 grams per day, you know that it is only possible if your kidneys let all sizes of proteins out. This only happens with nephrotic syndrome.

We will look at the specific aspects of nephrotic syndrome and see how they relate to excessive protein in the urine. Nephrotic syndrome affects multiple organ systems and eventually leads to several different problems. We will explore each problem in detail and learn how excessive protein in the urine is the root cause of all these problems.

Recurrent infections

When you have excessive protein in the urine, you are prone to infections. Your immune system relies on specific proteins to carry out your body’s defense. Those proteins bind to the germs and tag them for destruction. When you lose excessive protein in the urine, you lose these important proteins too. A recurrent infection is a known complication of nephrotic syndrome.

Excessive swelling

When you lose more than 3 grams of protein in your urine everyday, your blood albumin goes down significantly. Albumin is a type of protein that helps to keep water inside your blood vessels. If you would like to learn more about albumin and all the symptoms of low albumin, read this article: “Symptoms of low albumin.”

Without albumin, water will seep out of the blood vessels and cause swelling everywhere. At first, swelling starts at both the feet and ankles, but as the excessive protein loss in the urine continues, you start to get swelling everywhere. Eventually, your whole body gets swollen. You also get excessive fluid buildup inside your chest and abdomen. The excessive swelling of the whole body is called anasarca, and it is a characteristic feature of the nephrotic syndrome.

Low blood volume

Excessive protein loss in the urine causes water to go out of the blood vessels and makes your body swell up. At the same time, your blood volume goes down due to the lost water. When there is not enough blood in your circulation, you feel tired and your hands and feet get cold. Eventually, your heart rate goes up, and when things get really bad, your blood pressure starts to go down, and you feel dizzy and lightheaded. Low blood volume is a part of the nephrotic syndrome.

Cholesterol abnormalities and resulting heart disease

The movement and proper processing of cholesterol and other fats inside your body depends on specialized proteins. These proteins carry cholesterol and fats, taking them where they are needed. They also retrieve excess cholesterol and take it to the liver for proper processing and disposal. Different types of fats and cholesterols are essential to maintain a healthy, functioning body. However, when they are not properly regulated, excess fats and cholesterols can deposit themselves inside blood vessels and form plaques. Those plaques can impede blood flow and cause heart attacks or strokes. Excessive protein loss in the urine can lead to heart diseases and heart attacks. People with nephrotic syndrome have a significantly higher risk of heart attacks and strokes.

High risk for blood clots

The risk for blood clots is so high with nephrotic syndrome that some people already have blood clots by the time they get diagnosed with it. In fact, some people seek medical attention for symptoms of blood clots and nephrotic syndrome that are only discovered later.

Our blood clotting system is controlled by different types of proteins floating in our blood. These proteins closely coordinate the clotting process. They keep the blood as a liquid when it is inside the blood vessel. When they detect any cuts or breaks in the blood vessels, they form clots to prevent blood loss from bleeding. When you lose these important proteins in the urine, your clotting system become uncontrolled and uncoordinated. Your blood starts clotting for no reason. These blood clots can be very dangerous.

What to expect when diagnosed with nephrotic syndrome

You have to understand that nephrotic syndrome is the end result of several different types of diseases that damage your kidney’s filter. Any of those diseases can create big holes in the filter to let excessive amounts of protein in the urine and start nephrotic syndrome.

It is very important to get the diagnosis of nephrotic syndrome as soon as possible. Once nephrotic syndrome is diagnosed, you need to immediately start looking for the underlying cause. Sometimes, the cause is obvious, but other times, it may take a lot of investigation to pinpoint the cause. You need to work with an experienced kidney specialist to try to establish the root cause as soon as possible.

The kidney specialist will look at your urine under a microscope to identify certain clues that may point toward a certain disease. In many cases, a biopsy of the actual kidneys may be needed to establish the cause with certainty.

A kidney biopsy involves getting a small piece of the actual tissue from one of your kidneys. It is done by inserting a small needle into your kidneys from your back. Usually, it is done with an ultrasound or CT scan guiding the needle to the right spot.

They will examine the tissue sample under a microscope and visualize the actual filter elements of the kidneys; they will try to figure out what is letting the excessive amounts of protein escape into the urine.

The treatment will depend on the cause, and may involve the use of steroids or other medications to repair the microscopic filter inside your kidneys.

In addition to the specific treatment, it is also important to mitigate the effects of excessive protein loss in the urine. You may need blood thinners to help prevent blood clots. Antibiotics may be necessary to treat infections. You may need cholesterol medications to help lower cholesterol. To drain the excess fluids caused by swelling, you might need medications. The treatment of nephrotic syndrome is highly specialized and personalized based on your unique situation.

In conclusion, you need to think about nephrotic syndrome if you have excessive protein in your urine. Losing excessive amounts of protein is the root cause of all problems associated with nephrotic syndrome. It is important to get the diagnosis confirmed as soon as possible and work with an experienced kidney specialist to find the cause of the problem.