Sure, I will explain more.
Measuring serum creatinine is a useful and inexpensive method of evaluating renal dysfunction. Creatinine is a non-protein waste product of creatine phosphate metabolism by skeletal muscle tissue. Creatinine production is continuous and is proportional to muscle mass.
Creatinine is freely filtered and therefore the serum creatinine level depends on the Glomerular Filtration Rate (GFR). Renal dysfunction diminishes the ability to filter creatinine and the serum creatinine rises. The GFR is a measure of your kidney's ability to work.
Decreased Creatinine levels may be seen in: the elderly, persons with small stature, decreased muscle mass, or inadequate dietary protein. Muscle atrophy can also result in decreased serum creatinine level.
Low creatinine may just mean that your kidneys are working well, not that your blood is diluted.
A Urinalysis is a lab test of your urine. The specific gravity will show how dilute the urine is.
Urine sodium is a separate test and it is also an indication of dilute urine.
Unfortunately, if you are drinking a lot of fluid at work, this test may show that your urine is dilute anyway.