What is creatinine?

Creatinine is a nitrogenous compound product derived from creatine, a substance found in the muscles of the human body, and is a molecule of major importance for energy production in the muscles. To a smaller extent we obtain some creatinine via the consumption of food. Creatinine is a chemical waste molecule that is generated from the muscle metabolism. Approximately 2% of the body’s creatine is converted to creatinine every single day. Creatinine is formed with muscle activity, then transported through the bloodstream, further filtered by the kidneys and eventually excreted in the urine.

Because the muscle mass in the body is relatively constant from day to day, the creatinine production within our body’s remains normal, essentially unchanged on a daily basis. Slight increases in creatine levels can appear after meals, especially after ingestion of large quantities of meat, and some diurnal variation may occur, with a low point in the day at 7 A.M. and a peak at 7 P.M. Serious renal disorders, such as those of glomerulonephritis, pyelonephritis, and urinary obstruction, will cause abnormal elevations of creatinine.

Although it is a waste, creatinine serves a vital diagnostic function and is considered of significant importance to ensure proper and healthy renal function in the human body. Creatinine has been found to be a fairly reliable indicator of kidney functions.


Why measure the level of creatinine?

The creatinine blood test measures levels of creatinine contained in the blood of the patient. It is a routine examination, but it can also be prescribed in the case of suspected impairment of kidney function, in the case of kidney disease or dialysis patients. The creatinine level is interpreted in conjunction with another kidney function test called the blood urea nitrogen (BUN). The serum creatinine levels have much the same significance as the BUN test, but tend to rise later. Due to this matter, determinations of creatinine help to chronicle a disease process. Generally a doubling of creatinine within the human body, suggest a 50% reduction in kidney filtration rate, also known as the glomerular filtration rate (GFR).

General normal values are as follows; adult female: 0.5 to 1.1 mg/dL, adult male: 0.6 to 1.2 mg/dL, adolescent: 0.5 to 1.0 mg/dL, child: 0.3 to 0.7 mg/dL, infant: 0.2 to 0.4 mg/dL, newborn: 0.3 to 1.2 mg/dL.


Standard of preparation

Sampling is usually done in the morning in the hospital. There are no special preparations needed for this test. The doctor will advise and recommend if you need to be fasting prior to the blood examination. You should inform your doctor of any medication you are taking prior to the exam, as some medical treatments may interfere with the blood results.


Is the examination painful or dangerous?

The examination is neither painful nor dangerous. The patient may feel a tingling sensation with the entrance of the needle in the arm when blood is being extracted for examination.


How is the exam performed?

The exam consists of a simple blood sample test.