The sole reason why red blood cells are unable to replace damaged proteins is that red blood cells lack DNA and cell organelles such as nucleus, ribosomes and mitochondria which are crucial for protein synthesis, assembly and repair. In other words they lack both the information and the machinery for making or repair of proteins.
Due to lack of DNA and cell organelles, red blood cells cannot be able satisfy the central dogma which summarizes synthesis of proteins as DNA → RNA → proteins.
DNA has the genetic information on how proteins should be made, RNA is responsible for transferring the information from DNA in the cell nucleus to the ribosomes in the cytoplasm, then translating or decoding this information, which results in the making of protein.
Creatinine is a by-product of muscular metabolism. In the natural and normal scheme of things, this substance or waste product can be eliminated from the body. A high-serum creatinine level may cause kidney damage. In relation to the above question as to how high can creatinine levels go before death, it must be noted that kidneys have strong compensatory ability and by that as long as its still 50 percent functional, creatinine level won't be that high. Which leads us to a conclusion that, the lesser the kidney function level is, the higher the creatinine level.
On the other hand for the blood urea nitrogen (BUN) is the most stable blood constituent following death as it reaches antemortem (before death) levels and even after moderate decomposition.
Therefore, as long as the kidneys are functional, regardless of other factors such as the patient's condition/ diagnosis, these blood constituents are nearly normal.
C...? what's the question
