Two major things happen when the kidneys don't work. Remember, the kidneys are filters. When the filters don't work, we see:
Substances that should pass through the kidney don't get through and then build up in the blood. Increasing levels mean there is something wrong. Some of the substances include creatinine, BUN, acid-base & electrolytes, and drugs and toxins.
The higher the creatinine, the lower the glomerular filtration rate. This is a simplified way of saying the percentage of kidney function that someone has.
The higher the BUN is, the more likely we will see the signs and symptoms of the kidneys not working. These include:
The kidney becomes leaky, and we see things in the urine that are not supposed to be there.
We see protein in the urine when it leaks from the filters in the kidneys. When there is protein in the urine, it represents a problem. We call this proteinuria. We will want to measure the amount of protein that there is in the urine and the type.
Blood in the urine is from 2 things. It can be from any part of the "plumbing" that makes up the urinary tract or from the kidneys themselves. That patient's story gives us a good clue if the blood is from the kidneys or not. We call blood in the urine hematuria.