Nephrotic (ne-FRAH-tik) syndrome, or nephrosis (ne-FROH-sis), is a disorder of the filtering mechanism of the kidneys that causes the body to lose protein from the blood, which is then sent into the urine. Loss of protein results in such physical problems as excess body fluid, loss of appetite, and general tiredness. The syndrome is characterized by proteinuria (an excess amount of protein in the urine), hypoalbuminemia (an abnormally low level of albumin in the blood), hyperlipidemia (an excess of fats, especially cholesterol, in the blood), and edema * . The blood-filtering mechanism of the kidneys (glomerular membrane) may be damaged by infection, immune processes, toxins, and other factors. Nephrotic syndrome is a serious condition, but it can be treated effectively with medication and diet. Most children with the condition recover.
During the summer when Sally was seven years old, she stopped eating much of anything at meals, laid around the house all day, and seemed too tired to do her chores or play with friends. At first Sally's mother thought her daughter was just being lazy, but when Sally's whole body began to look puffy, especially her eyes, ankles, and abdomen, her mother began to worry.
The doctor identified Sally's puffiness as edema and asked Sally about how often she had been going to the bathroom. When Sally said she was urinating only about twice per day, the doctor suspected a kidney problem. The doctor ran several tests. An analysis of Sally's urine showed that it contained high levels of protein; and a blood test showed low levels of protein and high levels of cholesterol. These results made the doctor suspect nephrosis.
The doctor performed several additional tests to eliminate other diseases, and then he confirmed the diagnosis with a kidney biopsy * . Ultimately, he could not figure out why Sally had developed nephrosis. He explained to Sally and her parents that her condition could not be cured but that medications and a low-fat, low-salt diet would help relieve the symptoms.
The kidneys are a pair of bean-shaped organs located in the human abdomen just above the waist. Their chief role is to filter wastes and excess water out of the blood. The filtering units in the kidney are tiny blood vessels (or capillaries) called glomeruli (glom-ER-you-li), which remove body waste from the body as urine. Nephrosis is a kidney disease caused by a defect in the glomeruli.
The earliest symptom of nephrosis is the observation of foamy-looking urine when released into the toilet. Excess proteins in the urine often produce such an effect. The most common symptom of nephrosis is edema in the body, which often shows up as puffiness around the eyes, especially after first waking up from sleep. Puffiness in the hands, feet, ankles, and legs is often noticed, along with a temporary pitting of the skin at some locations. Excess fluid is also found in the pleural cavity (which is the space in the chest that surrounds the lungs) and in the peritoneal cavity (the space in the abdomen that contains the stomach, liver, and intestines). The individual also feels increasingly fatigued and weak, with an associated reduction in weight due to a lessened appetite. Muscles become smaller and weaker. Abdominal pain, trouble breathing, headaches, fever, and skin sores can also occur. When the body becomes weakened, the hair and nails become brittle, and bones break easily as the body continues to lose nutrients.
Children as well as adults can develop nephrosis. Children—more likely boys—are at an increased risk from nephrosis, especially from minimal change nephrotic syndrome, when they are in the range of ages from 18 months to 4 years. In adults, the risk from the disease, especially with regard to membranoproliferative glomerulonephritis, is about equal between men and women. As of 2016, the cause of the glomeruli defect that often results in nephrosis was unknown. One fact that is known about nephrosis is that it can develop as part of other diseases, including the following:
In addition, overuse of some drugs (such as laxatives), exposure to certain chemicals (e.g., lead or carbon tetrachloride), and, in some people, exposure to certain allergens (such as poison ivy, poison oak, poison sumac, and insect stings) can affect the functioning of the kidneys and lead to nephrosis.
There are four primary types of nephrosis. The types are diagnosed based on the appearance of the kidney tissue in biopsies. The most common type is minimal change nephrotic syndrome (MCNS), or minimal change disease. MCNS often occurs after upper respiratory infections, during the presence of cancerous tumors, and with adverse reactions to drugs (such as nonsteroidal anti-inflammatory drugs [NSAIDs] such as aspirin, ibuprofen * , and naproxen) and bee stings. It occurs in children in about 90 percent of nephrotic cases but is found in only one in five adult cases of the condition.
The other three types of nephrosis are classified as membranoproliferative glomerulonephritis (MPGN), which is caused by groups of antigens and antibodies deposited in the glomerular basement membrane; membranous glomerulopathy (membranous), which damages the glomerular basement membrane, the membrane that separates blood from urine; and focal segmental glomerulosclerosis (FSGS), which involves only some of the glomeruli, includes only portions of those affected glomeruli, and produces scarring within the affected glomeruli.
Several tests are available to diagnose nephrosis. The most important is a urine test that shows the presence of proteinuria. When a person has nephrosis, the level of proteinuria in the urine is greater than 2 grams when measured over a 24-hour urine collection period.
As a result of abundant proteinuria, the patient develops hypoalbuminemia, which is demonstrated by testing the blood for albumin. Levels generally below 3 grams per deciliter indicate a very low level of the water-soluble protein albumin in blood serum.
The condition called hypercholesterolemia is when the body contains high levels of cholesterol in the blood. When nephrosis is present, test results indicate an elevated low-density lipoprotein (LDL), which transports cholesterol within the body, along with a higher-than-normal level of very low-density lipoprotein (VLDL). Both LDL and VLDL are commonly referred to as bad cholesterol.
Other tests include evaluating the plasma concentrations of electrolytes (such as calcium, potassium, and sodium), urea, and creatinine in order to test the efficiency of the kidneys to filter out waste products.
A kidney biopsy may also be performed. During the biopsy, a thin needle is inserted under the ribs and a tiny sample of the kidney is removed for examination with an electron microscope, which provides high-quality images that are magnified millions of times for accurate analysis of the sample.
It is important to perform several tests because other diseases and conditions can act like nephrosis. Numerous tests help to eliminate the possibility of other problems so that nephrosis can be accurately diagnosed within patients.
How nephrosis is treated depends on its cause. If it is caused by another disease, that underlying disease is treated. If the cause of nephrosis is not known, the symptoms may be treated with antibiotic drugs to reduce infections. Diuretics * are used to reduce edema. To reduce protein loss in the urine and hypertension, angiotensin-converting enzyme (ACE) inhibitors are prescribed. Prednisone, by itself or with immunosuppressive drugs, is also often used to reduce protein loss. Medicines to reduce high blood pressure, cholesterol, and triglycerides * may be given. A corticosteroid is used to reduce signs of inflammation and allergic reactions. A diet low in fat (especially saturated fat), cholesterol, and salt might be recommended, and fluid intake might be restricted.
People with nephrosis, especially children, often recover when nephrosis is treated promptly and early. However, nephrotic patients may be at increased risk for complications from heart diseases and atherosclerosis, other kidney diseases, infections, and malnutrition. If the kidneys lose their ability to function, dialysis * may be necessary. Difficulties with blood pressure control may also occur.
See also Diabetes • Hypertension • Kidney Disease • Lupus
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* biopsy (BI-op-see) is a test in which a small sample of skin or other body tissue is removed and examined for signs of disease.
* edema (e-DEE-ma) means swelling in the body's tissues caused by excess fluids.
* ibuprofen (eye-bew-PRO-fin) is a nonsteroidal anti-inflammatory drug (NSAID) used to reduce fever and relieve pain or inflammation
* diuretics (dye-yoor-EH-tiks) are medications that increase the body's output of urine.
* triglycerides (try-GLISS-eh-rides) are a type of fatty substances found in the blood.
* dialysis (dye-AL-uh-sis) is a process that removes waste, toxins (poisons), and extra fluid from the blood. Usually dialysis is done when a person's kidneys are unable to perform these functions normally.