According to the Cleveland Clinic, “Proteinuria is due to increased levels of protein in the urine.” Your kidneys filter waste products from your blood while retaining what your body needs — including proteins. However, some diseases and conditions allow proteins to pass through the filters of your kidneys, causing protein in urine.
HOW DOES PROTEIN GET INTO URINE? (1)
Protein gets into the urine if the kidneys aren’t working properly. Normally, glomeruli, which are tiny loops of capillaries (blood vessels) in the kidneys, filter waste products and excess water from the blood.
Glomeruli pass these substances, but not larger proteins and blood cells, into the urine. If smaller proteins sneak through the glomeruli, tubules (long, thin, hollow tubes in the kidneys) recapture those proteins and keep them in the body.
However, if the glomeruli or tubules are damaged, if there is a problem with the reabsorption process of the proteins, or if there is an excessive protein load, the proteins will flow into the urine.
WHAT ARE THE SYMPTOMS OF PROTEINURIA? (2)
Often, someone with proteinuria doesn’t experience symptoms, especially if kidneys are just beginning to have problems. However, if proteinuria is advanced, symptoms can include:
- More frequent urination
- Shortness of breath
- Nausea and vomiting
- Swelling in the face, belly, feet or ankles
- Lack of appetite
- Muscle cramping at night
- Puffiness around the eyes, especially in the morning
- Foamy or bubbly urine
Conditions that can cause a temporary rise in the levels of protein in urine, but don’t necessarily indicate kidney damage, include:
However, according to the Mayo Clinic (2), there are diseases and conditions that can cause persistently elevated levels of protein in urine, which might indicate kidney disease, include:
- Amyloidosis (buildup of abnormal proteins in your organs)
- Certain drugs, such as nonsteroidal anti-inflammatory drugs
- Chronic kidney disease
- Endocarditis (an infection of the inner lining of the heart)
- Focal segmental glomerulosclerosis (FSGS)
- Glomerulonephritis (inflammation in the kidney cells that filter waste from the blood)
- Heart disease
- Heart failure
- High blood pressure (hypertension)
- Hodgkin’s lymphoma (Hodgkin’s disease)
- IgA nephropathy (Berger’s disease) (kidney inflammation resulting from a buildup of the antibody immunoglobulin A)
- Kidney infection (pyelonephritis)
- Multiple myeloma
- Nephrotic syndrome (damage to small filtering blood vessels in the kidneys)
- Orthostatic proteinuria (urine protein level rises when in an upright position)
- Rheumatoid arthritis (inflammatory joint disease)
- Sarcoidosis (collections of inflammatory cells in the body)
- Sickle cell anemia
HOW TO TEST FOR PROTEINURIA (3)
The only way to know if you have protein in your urine is to have a urine test. The test will measure the levels of protein in your urine.
The name of the urine test that measures the level of albumin in your urine is called the urine albumin-to-creatinine ratio (UACR). A UACR compares the level of albumin to the level of creatinine (a waste product in your blood that comes from your muscles). A normal UACR is less than 30mg/g.
Amyloid can harm the kidneys’ filtering system, causing protein to leak from your blood into your urine. The kidneys’ ability to remove waste products from your body is lowered, which may eventually lead to kidney failure and the need for dialysis.
When you have a patient with proteinuria, investigate why and don’t assume the obvious. There are many causes, one of which may be amyloidosis.
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