What is nephrotic-range proteinuria?
Nephrotic syndrome is a collection of symptoms that often indicate kidney damage, usually caused by another condition. One of the major symptoms is proteinuria, which means that there are large amounts of protein in the urine. One of the functions of the kidneys are to keep a protein found in the blood, called albumin, from passing into the urine. In this disorder, the body lets some of this protein into the urine.
Nephrotic-range proteinuria refers to nephrotic syndrome that has proteinuria with an albumin to creatinine ratio (ACR) of over 250 mg/mmol (milligrams per millimole), which is very high. (Albumin is the protein referred to previously, while creatinine is a normal waste product that appears in the blood.)
Nephrotic-range proteinuria can affect any age, but is most commonly found in adults. Research indicates that the disease is slightly more common in men than in women.
What are the symptoms of nephrotic-range proteinuria?
- Proteinuria: large amounts of protein in urine
- Hypoalbuminia: Low levels of albumin in the blood
- Hyperlipidemia: Abnormally high levels of fat and cholesterol in the blood
- Edema: Swelling, usually in the legs and feet
- Weight gain
- Foamy urine
- Loss of appetite
The loss of different proteins from the body with this disease can also lead to other complications, including blood clots, hypertension (high blood pressure), hypothyroidism, anemia, coronary heart disease, acute kidney injury, and an increased risk of infections.
What causes nephrotic-range proteinuria?
Nephrotic syndrome is the result of a problem with the kidneys’ filters, which are called glomeruli. These are tiny blood vessels that filter out wastes and excess fluids from the blood, turn them into urine, and then send them to the bladder. When the glomeruli are damaged, proteins from the blood can leak into the urine.
Albumin is a protein that acts like a sponge, pulling in extra fluid from the body into the bloodstream, where it stays until the kidneys remove it. When albumin leaks into the urine, blood loses its ability to absorb extra fluid, which is what causes the symptoms of the disorder.
Nephrotic syndrome is caused by diseases that damage the glomeruli. Some of these diseases include: diabetes, lupus, membranous nephropathy, minimal change disease (the most common cause in children), amyloidosis, blood clots in kidney veins, heart failure, and focal segmental glomerulosclerosis.
How is nephrotic-range proteinuria diagnosed?
Nephrotic-range proteinuria is diagnosed using the following procedures:
- Urine sample tests, including:
- Dipstick tests, which measure the amount of albumin in patient’s urine
- A single urine sample and/or a 24-hour collection of urine to be sent to a lab for analysis
- Blood tests
- Kidney biopsy
What are the treatments for nephrotic-range proteinuria?
The most important part of treating nephrotic-range proteinuria is addressing the underlying cause for it. Treatment for nephrotic syndrome’s specific symptoms include:
- Medications for lowering blood pressure
- Medication to lower cholesterol
- Vaccinations and yearly flu shots to lower risk of infection
- Water pills, or diuretics, that increase the kidney’s fluid output
- A diet low in sodium to reduce swelling caused by edema
- A diet low in saturated fat and cholesterol to reduce hyperlipidemia
Where can I find out more about nephrotic-range proteinuria?