The Importance of Checking Serum Creatinine Level

Creatinine is the metabolic wastes of muscle in the body and it is one of the most commonly adopted indicators of kidney function in clinic, therefore it is very important to have regular check of serum creatinine in case of kidney diseases so as to have clear understanding of the illness condition and progression.

Creatinine level has much to do with the muscle mass and is not easy to be affected by the diets. Creatinine is small molecular substance and it can be filtered by the glomeruli and very few will be re-absorbed in the renal tubules and nearly all the creatinine will be discharged with urine.

Since the creatinine is mainly discharged by the kidneys and its concentration in the blood is mainly determined by the glomerular filtration rate (GFR). In case of persistent increased creatinine level and other physiological factors (over-eating of meat, injection of creatine, etc) can be ruled out, it indicates that the renal parenchyma have been damages, that is why serum creatinine level is important in measuring kidney functions.

However creatinine is not a sensitive indicator. This is because the kidneys have great compensatory ability and only when the more than 2/3 kidney functions are affected can there be obvious increase of serum creatinine and at this time, the kidneys have been severely damaged and patients will feel dizziness, vomiting, nausea, etc due to the excessive accumulation of creatinine and other metabolic wastes in the body.

Though the criterions for normal creatinine level vary from hospital to hospital, the general range for normal creatinine is 0.5-1.0mg/ml for female and 0.7-1.2 mg/dl for male. And creatinine has a certain individual difference. For example creatinine of 2.0 may indicates normal kidneys in a strong male while creatinine 1.3 might indicate renal insufficiency or renal dysfunction in a weak female.

A more accurate and sensitive indicator of kidney function is to measure how much creatinine is discharged out of the body through the kidneys, that is the creatinine clearance and it can reflect the GFR and kidney functions. Creatinine clearance lower than 6-10ml/min indicates end stage renal disease and dialysis is needed.