Popular Science | If there is a + sign on urine protein, will it cause uremia?

1. What is proteinuria?

The protein content in the urine of healthy people is very low, with a daily excretion of less than 150 mg. When the protein content in the urine increases, the urine routine test will show protein+, which is called proteinuria.

2.Why does kidney disease cause proteinuria?

The kidney is like a "net bag" that holds the protein in the body and discharges metabolic waste and excess water. Some small molecular proteins that leak out of the net are reabsorbed through the drainage pipes (renal tubules) below the net bag. When there is a problem with the "net bag", a large amount of protein leaks out, or when there is a problem with the drainage pipe, the ability to reabsorb protein decreases, and proteinuria will occur.

3. If urine contains protein+, does that mean I have kidney disease?

① Physiological proteinuria: during strenuous exercise, fever or cold;

② Postural proteinuria: In tall and thin adolescents, when standing upright, the lordosis of the spine compresses the left renal vein, causing increased local venous pressure. The proteinuria disappears after resting in a supine position, which is called Nutcracker syndrome.

③ Pseudoproteinuria: cystitis, urethritis, urethral bleeding and secretions mixed in urine;

④ Pathological proteinuria: nephritis, renal ischemia, diabetic nephropathy, systemic lupus erythematosus, Henoch-Schonlein purpura, hemolytic anemia, crush syndrome, multiple myeloma, plasma cell disease, light chain disease, etc. Therefore, not all urine protein+ means kidney disease.

4. Can kidney disease that causes proteinuria be cured?

When it is found that the urine protein is caused by kidney disease, the next step is to actively explore the cause of kidney disease leading to proteinuria. Do some blood tests, urine tests, imaging tests, and renal puncture biopsy when necessary to find out the type of kidney disease. The prognosis of different kidney diseases is also different. For example, a considerable part of membranous nephropathy and minimal change nephropathy can be completely cured.

5. If the protein in the urine has not disappeared for many years, will it develop into uremia?

Some patients have kidney disease and always have protein in their urine, but there are also many patients with proteinuria who can control the disease through proper treatment and their kidney function will not deteriorate.

6. If kidney function is already poor, will it develop into uremia?

Creatinine and urea nitrogen are indicators of renal function. The creatinine of some patients with chronic renal failure shows a gradual increasing trend over the long term. However, with proper treatment, the rate of creatinine increase can be slowed, and uremia will not occur during normal life.

**Summary:** Healthy people have very little protein in their urine. Finding protein in urine is not a big deal. The key is to actively look for the cause. Not all proteinuria is caused by kidney disease, and proteinuria caused by kidney disease does not necessarily cause uremia. Clear diagnosis, reasonable treatment, and regular medication are the key.