explain this the kidney reserve is such that about 50% of the kidney function must be lost before creatinine level in blood is raisededit

The kidneys are responsible for filtering waste products from the blood, including creatinine. Creatinine is a waste product that comes from the normal wear and tear on muscles of the body. The kidneys filter out creatinine from the blood and excrete it into the urine.

The term "kidney reserve" refers to the ability of the kidneys to compensate for loss in function. The kidneys have a large reserve capacity, which means they can continue to function normally even when they are partially damaged or impaired.

Here's a step-by-step explanation:

1. When the kidneys are healthy, they are able to filter out creatinine efficiently, keeping the level of creatinine in the blood within a normal range.

2. If the kidneys become damaged or impaired, they may not be able to filter out creatinine as efficiently. This can cause the level of creatinine in the blood to rise.

3. However, because the kidneys have a large reserve capacity, they can often continue to function normally and keep the level of creatinine in the blood within a normal range even when they are partially damaged or impaired.

4. It is only when about 50% of the kidney function is lost that the kidneys can no longer compensate for the loss in function. At this point, the level of creatinine in the blood may start to rise.

5. Therefore, a rise in the level of creatinine in the blood is often a sign that the kidneys have lost about 50% of their function and can no longer compensate for the loss in function. This is why doctors often use the level of creatinine in the blood to assess kidney function.