Your kidneys filter waste products from your blood while keeping 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.

Conditions that can cause a temporary rise in the levels of protein in urine, but don't necessarily indicate kidney damage, include:

1. Dehydration — when the body doesn't have enough water and other fluids to work as it should.
2. Exposure to extreme cold
3. Fever
4. Strenuous exercise

Tests to identify protein in urine are critical for diagnosing and screening for diseases of the kidneys or other conditions affecting kidney function. These tests are also used to monitor disease progression and treatment effect. These diseases and conditions include:

1. Chronic kidney disease
2. Diabetic nephropathy (kidney disease)
3. Focal segmental glomerulosclerosis (FSGS)
4. Glomerulonephritis (inflammation in the kidney cells that filter waste from the blood)
5. High blood pressure (hypertension)
6. IgA nephropathy (Berger disease) (kidney inflammation resulting from a buildup of the antibody immunoglobulin A)
7. Lupus
8. Membranous nephropathy
9. Multiple myeloma
10. Nephrotic syndrome (damage to small filtering blood vessels in the kidneys)
11. Preeclampsia

Other conditions and factors affecting the kidneys that may result in protein in urine include:

1. Amyloidosis
2. Certain drugs, such as nonsteroidal anti-inflammatory drugs
3. Heart disease
4. Heart failure — a condition in which the heart doesn't pump blood as well as it should.
5. Hodgkin lymphoma (Hodgkin disease)
6. Kidney infection (also called pyelonephritis)
7. Malaria
8. Orthostatic proteinuria (urine protein level rises when in an upright position)
9. Rheumatoid arthritis