Nephrotic syndrome refers to a group of symptoms that occur when there is something wrong with your kidneys. It can affect people of all ages and is often treatable. Kidney damage may be suspected if an individual shows any of the following symptoms:
- Edema: Swelling of the face, hands, feet, ankles, and legs
- Albuminuria: The presence of too much albumin in the urine.
- Hypoalbuminemia: Abnormally low levels of albumin the blood.
- Hyperlipidemia: Abnormally high lipid (fat) levels in the blood.
When the kidney’s filtering units called glomeruli are damaged, albumin can leak into the urine and nephrotic syndrome occurs. They are tiny blood vessels that eliminate extra fluids and wastes from the blood and send them to the urinary bladder as urine. They also allow the blood to keep proteins and cells that the body needs and filter out waste products as blood passes through the kidneys.
What could be the causes of nephrotic syndrome?
Nephrotic syndrome can either be due to primary (a condition that only affects the kidneys) or secondary causes (other conditions that also affect normal kidney function). Most people who experience nephrotic syndrome often have secondary causes.
Primary Nephrotic Syndrome
The primary causes of nephrotic syndrome include:
- Membranous nephropathy or focal segmental glomerulosclerosis (FSGS): This condition causes glomeruli scars and is commonly observed in adults.
- Minimal change disease (MCD): This kidney disorder is commonly observed in children.
- Other kidney problems: Alport syndrome, IgA nephropathy, IgM nephropathy, C1q nephropathy, and membranoproliferative glomerulonephritis (MPGN).
These kidney diseases target the glomeruli for unknown reasons.
Secondary Nephrotic Syndrome
The secondary causes of nephrotic syndrome are usually associated with other underlying medical conditions, such as:
- Viral infections (HIV, hepatitis, and cytomegalovirus, among others)
- Cancer (lymphoma)
- Certain medications, toxins, or drug abuse
- Heart failure
- Renal vein thrombosis (RVT)
The most common secondary cause of nephrotic syndrome in adults is diabetes.
Signs and Symptoms of Nephrotic Syndrome
People who have nephrotic syndrome may experience any of the following symptoms along with albuminuria, hyperlipidemia, and hypoalbuminemia:
- Edema (swelling of the face, hands, ankles, feet, and legs)
- Loss of appetite
- Weight gain
- Passing foamy or frothy urine
Nephrotic syndrome may go undetected until people consult their doctor and undergo routine tests for urine and blood. The results of these tests can show any abnormalities in your body and blood.
People who have underlying medical conditions, such as lupus, amyloidosis, and diabetes are more prone to experiencing nephrotic syndrome. Those who regularly take nonsteroidal anti-inflammatory drugs (NSAIDs) also have an increased risk of nephrotic syndrome.
Other types of infections that put you at risk of getting nephrotic syndrome include:
A number of complications may occur in people with nephrotic syndrome due to the loss of certain proteins in the body. One complication is the formation of blood clots since the proteins that prevent their formation are eliminated through the urine. These blood clots can obstruct blood and oxygen flow through the blood vessels.
When immune system proteins or immunoglobulins, which help combat infections and diseases are lost, people tend to become more susceptible to developing infections, such as:
- Skin infections (cellulitis)
- Lung infections (pneumonia)
- Abdominal infections (peritonitis)
- Brain and spine infections (meningitis)
Certain medications for the treatment of nephrotic syndrome may also lead people to have an increased risk of developing infections.
People with nephrotic syndrome may also develop any of the following complications:
- Anemia: This condition occurs when there is not enough hemoglobin or red blood cells (RBCs) in the blood. Hemoglobin is an iron-containing protein that carries oxygen all over the body. When people have anemia, the cells in their body will not get enough oxygen levels.
- Hypertension or High Blood Pressure: This is a common condition that is characterized by a chronic force of blood against the walls of the arteries, leading to cardiovascular problems, such as heart disease.
- Coronary Heart Disease (CHD): This condition usually occurs when there is an abnormal accumulation of cholesterol on the walls of the arteries, creating a plaque. In CHD, the arteries become narrowed and hardened.
- Acute Kidney Injury (AKI): This condition refers to a sudden loss of kidney function that develops within a few hours to days.
- Hypothyroidism: This endocrine disorder is also called as low thyroid or underactive thyroid, which occurs when the thyroid gland is unable to sufficiently produce thyroid hormones. Symptoms of hypothyroidism include feeling tired, poor tolerance to cold, depression, constipation, and weight gain.
A simple urine test along with blood tests are performed to check kidney function. Doctors may also check if you have other underlying conditions, which could be the cause of nephrotic syndrome. In some cases, a kidney biopsy will be performed, in which a tissue sample is collected and further examined under a microscope.
Treatment for nephrotic syndrome usually depends on its underlying cause, including some steps to minimize the risks of infection, lower high blood pressure, high cholesterol, and water retention. Its treatment also includes certain dietary changes and medications.
The progression of kidney disease, which causes nephrotic syndrome, can be significantly slowed down with the help of blood pressure medications. These medications include angiotensin receptor blockers (ARBs) and angiotensin-converting enzyme (ACE) inhibitors, which help reduce glomeruli pressure and albuminuria. To help regulate blood pressure levels, there are people who take two or more types of medications.
Aside from taking ARBs and ACE inhibitors, diuretics can also help the kidneys eliminate extra fluid in the blood, reduce swelling, and lower blood pressure levels. Other blood pressure medications that may be useful are calcium channel blockers and beta blockers. To help lower cholesterol levels, statin medications may be prescribed by your healthcare provider.
Blood thinners are also given to individuals with nephrotic syndrome, particularly those who have blood clot formation. Once the underlying cause has been treated, nephrotic syndrome also tends to go away.
Can nephrotic syndrome be prevented?
Some causes of nephrotic syndrome cannot be prevented, but there are steps you can take to prevent glomeruli damage. Moreover, treating any underlying conditions can help control the symptoms from worsening.