Proteinuria - Causes, Symptoms, Diagnosis, and Management

Introduction:

Proteins are a set of molecules that consist of amino acids linked together by peptide bonds. They are present inside the body and are used by the cells to derive energy to carry out their daily activities. One must consume sufficient amounts of proteins throughout the diet to keep the body healthy. After the cells use proteins, they are sent to the kidneys. Normally the kidneys do not allow the proteins to pass through the urine. However, if the kidneys are damaged or unable to function, excess proteins pass through the urine, and the condition is known as proteinuria.

What Is Proteinuria?

Proteinuria occurs when the kidneys are not functioning properly, and the urine has large amounts of proteins. The kidneys consist of a cluster of tiny blood vessels (glomeruli) that works to filter blood. Under normal conditions, the proteins and other large molecules are sent back to the blood because they are required by the body for daily activities. The glomeruli do not allow even the small proteins to leave the body. However, if the kidneys are damaged or the patient is suffering from long-standing kidney disease, these proteins escape the glomeruli and accumulate in the urine. If the level of proteins in the urine goes above 150 milligrams per day, proteinuria can be suspected. It is important to undergo treatment for kidney disease at the earliest.

What Are the Causes of Proteinuria?

Under normal conditions, the kidneys filter blood and reabsorb the proteins. They are sent back to the blood because proteins are the building blocks of the body and are required to carry out the biochemical reaction in the body. If the filtration units of the kidneys fail to work, the proteins escape into the urine resulting in proteinuria. The causes of proteinuria have been described below:

1. Dehydration and Strenuous Exercise - Dehydration and exercise usually cause temporary proteinuria. During exercise, the person loses a large amount of fluids and becomes dehydrated. If the fluids are not replenished, it becomes difficult for the kidneys to reabsorb proteins. As a result, the proteins are excreted in large amounts in the urine.

2. Emotional Stress and Anxiety - Stress and anxiety can also increase the protein content in the urine. It is because the filtering units of the kidneys get damaged in extreme stress and are unable to reabsorb proteins leading to proteinuria.

3. Kidney Stones - Stones form in the kidneys when the minerals and salts in the urine clump together. If the stones are present for a long time, they damage the kidneys. As a result, the kidneys are unable to filter proteins from the blood, and they get excreted in the urine.

4. Glomerulonephritis - The kidney consists of a cluster of tiny blood vessels known as glomeruli that work to filter the blood. In the case of glomerulonephritis, the glomeruli fail to reabsorb proteins from the blood. As a result, the protein concentration in the urine increases, leading to proteinuria.

5. Multiple Myeloma - It is a type of cancer in which abnormal proteins are found in the plasma cells. These proteins enter the tubules present in the kidneys and join with other proteins. As a result, large protein molecules are formed in the urine resulting in damage to the kidney tubules.

6. Preeclampsia - It is a condition in which hypertension (high blood pressure) and proteinuria occur during pregnancy. Proteinuria in pregnancy mainly occurs due to a defect in the functioning of the placenta.

7. Congestive Heart Failure - It is a condition in which the heart fails to pump blood to the body organs, including the kidneys. If the kidneys do not receive a sufficient quantity of blood, the filtration units present in them fail to function. As a result, proteins and other substances accumulate in the urine.

8. Lupus Nephritis - The kidneys consist of thousands of small units known as nephrons that form urine and remove the waste products from the body. In the case of lupus nephritis, inflammation of the nephrons occurs due to lupus antibodies. As a result, the kidneys get damaged, and the urine shows the presence of proteins and blood.

What Are Some of the Symptoms of Proteinuria?

The patient does not experience any symptoms in the initial stage. As the condition progresses further, the following symptoms are usually seen:

• The patient needs to urinate frequently, and the urine appears foamy or bubbly.

• Edema or swelling in the feet, face, ankles, and belly.

• The patient is unable to eat and feels tired the whole day.

• It becomes difficult to breathe.

• The area around the eyes becomes puffy in the morning.

• The patient is unable to sleep at night because of muscle pain.

What Are the Types of Proteinuria?

The different types of proteinuria are described in the table below:

What Methods Are Used to Diagnose Proteinuria?

The doctor recommends the following tests to diagnose proteinuria:

1. Urinalysis -The patient needs to collect the urine in a container, and it is sent to the laboratory for further evaluation.

   • Visual Examination - The laboratory technician checks the appearance of urine. If the urine appears foamy or shows the presence of bubbles, the presence of proteins is usually suspected. If the urine appears cloudy or contains blood, it is a sign of urinary tract infection.

   • Dipstick Test - A dipstick is a thin stick with chemicals on it that change its colors if the substances in the urine are above or below their normal values. The dipstick test check for the following:

     • Urine pH (Potential of Hydrogen) - If the pH is acidic, which is below seven, it is indicative of kidney disease.

     • Urine Concentration - The urine concentration is low if the person does not drink a sufficient quantity of water daily.

     • Glucose Levels - The glucose levels are high in the urine if the patient is diabetic.

     • Proteins - If the proteins present in the urine are less than 150 milligrams per day, it is considered normal.

     • Bilirubin - The red blood cells break down to form bilirubin which is removed by the liver. If bilirubin is present in the urine, liver disease can be suspected.

     • Blood - Blood might be present in the urine due to infections, kidney stones, bladder cancer, and blood disorders.

   • Microscopic Examination - The urine is examined under the microscope to detect the bacteria, crystals, and red and white blood cells. If the white blood cells are present in increased numbers, urinary tract infections can be suspected.

2. Blood Tests - The doctor may recommend the patient undergo a blood test to check the following:

   • Creatinine Levels - Creatinine is a waste product formed after muscle activity. It reaches the kidneys through the blood and gets expelled from the body. A blood test helps determine creatinine levels. If the blood contains a large amount of creatinine, the kidneys or their filtration units are not functioning correctly.

   • Serum Protein Levels - Serum is a portion of the blood that contains a variety of proteins and does not play any role in blood clotting. Albumin and globulin are the two major types of proteins present in the blood serum. Proteinuria occurs when the levels of albumin are raised in the body.

3. Urine Protein Electrophoresis Test - This test helps to detect the proteins in the urine, their types, and the levels of each type of protein. First, the patient collects the urine in a container. Next, the urine sample is sent to the laboratory, where it is placed on paper. Electric current is then passed to the urine, and the proteins get separated from the urine.

4. Imaging Tests - Imaging tests like ultrasound and computed tomography (CT) scans are done to detect stones, tumors, and other conditions affecting the kidneys with the help of three-dimensional images (3D) images obtained from these tests.

5. Kidney Biopsy - In this procedure, the doctor removes a small piece of kidney tissue and examines it to detect the presence of abnormalities.

How Is Proteinuria Managed?

The treatment of proteinuria depends on the condition that caused it. If it is due to temporary conditions like dehydration, exercise, emotional stress, anxiety, and fever, it does not require any specific treatment. It subsides as soon as these temporary conditions are treated. Treatment is required if proteinuria is due to kidney diseases, diabetes, preeclampsia, and hypertension. The treatment includes the following:

• Diet - The doctor recommends certain dietary changes if the patient is suffering from kidney diseases, diabetes, and high blood pressure to maintain an optimum protein balance in the body. For example, limiting salt consumption, avoiding animal foods (fish, meat, chicken), drinking plenty of water to increase the urine concentration, and having citrus fruits like oranges, lemons, and grapes.

• Medications - Patients suffering from hypertension and diabetes need to continue their medications as prescribed. The doctor recommends the following medications to control proteinuria:

  • Diuretics - These drugs work to reduce the fluid levels of the body because of the fluid overload in proteinuria. Thiazide diuretics like Indapamide and Chlorthalidone have proven to be effective in reducing protein levels.

  • Calcium Channel Blockers - The calcium channel blockers like Diltiazem and Verapamil are used to treat mild to moderate proteinuria.

• Maintaining Weight - It is important to maintain a healthy weight, as excessive weight (obesity) can cause kidney problems.

What Are the Complications of Proteinuria?

The complications of proteinuria include the following:

1. Pulmonary Edema - It is a condition in which the fluid accumulated in the lungs causes breathing difficulties in the patient. Proteinuria patients suffer from fluid overload if left untreated for a long time.

2. Kidney Failure - The kidneys maintain the level of fluids in the body. In the case of kidney failure, the fluid remains retained within the organs of the body, like the heart, and lungs, and causes symptoms of chest pain, difficulty in breathing, and swelling in the legs and ankle. The kidneys completely lose their ability to work.

3. Bacterial Peritonitis - If proteinuria is left untreated for a long time, the fluid accumulates in the abdomen and provides a medium for bacterial growth.

Conclusion:

Proteinuria, or the increased protein levels in the urine, occurs when the kidneys cannot filter blood. Normally, the proteins are returned to the bloodstream and are not allowed to leave the body. Proteinuria occurs if the levels of protein in the urine are more than 150 milligrams per day. The patient must notify the symptoms of proteinuria and consult the doctor at the earliest. It is because fluid levels in the body increase rapidly if the condition is left untreated for a long time. There are no home remedies available to control protein levels. However, timely diagnosis and treatment of proteinuria help the patient live a healthy life ahead.