These measures provide an indication of renal perfusion. An elevated BUN generally reflects intravascular depletion. Creatinine is a useful indicator of acute renal failure. The CBC may provide some indication of hemoconcentration in cases of dehydration. The WBCs and differential cell count are useful indicators of infection.
Platelets can elevate as acute phase reactants.
The specific gravity of the urine is related to the patient's hydration state. In cases of renal disease, it can help classify the condition. Urine ions can be specifically requested, and are helpful in determining whether sodium is being retained or not. A true measure of serum osmolarity can be compared to the calculated osmolarity. The osmolarity of serum determines whether a patient is in an isotonic state or if this state has been disturbed.