Serum creatinine is a good marker of renal function (for reasons discussed on another page on this website). this is why when the serum creatinine level is increased above its normal limit, in most cases, this means that the kidneys are not excreting the creatinine as they should.
But, sometimes, there may be another explanation. Several factors other than renal function can affect serum creatinine levels. If one or more of these factors are present, we may be misinterpreting the serum creatinine level in that patient. Here are some of those factors (listed in no particular order):