Creatinine is a waste product made by the body during regular metabolism.
It is excreted into the urine by the kidneys. A serum creatinine
test measures the level of creatinine in the blood.
The level of creatinine in the blood is a good measure of overall
When the kidneys are not working properly for any reason, they are
not able to excrete creatinine into the urine. When this happens,
the level of creatinine in the blood rises.
The normal level of creatinine varies slightly based on age, body
size, and sex. The level also changes during pregnancy.
However, the normal level is usually between 0.5 and 1.4 milligrams
per deciliter (mg/dl).
It is increased in acute or chronic renal failure; urinary tract
obstruction, nephrotoxic drugs.
It is decreased in reduced muscle mass, possible drug effect.
This test is ordered for different reasons. For example, healthcare
providers may order this test when they think a person is dehydrated
or has kidney damage.
This test may also be ordered before or after a provider prescribes
The main reason to order the test is to make sure the kidneys are
. To perform a serum creatinine test, a blood sample is taken from
a vein on the forearm or hand.
A positive test means - An elevated value for this test can occur
in many different situations, including:
- decreased blood flow to the kidneys. This can occur with severe
dehydration, massive blood loss, or congestive heart failure. Blockage
in the kidney arteries, called renal artery stenosis, can also cause
an elevated value on this test.
- kidney damage or failure, which may be due to high blood pressure
or diabetes. An inherited condition called polycystic kidney disease
can also damage the kidneys. Damage to the kidneys can also occur
when the blood calcium level is too high, called hypercalcemia.
A cancer called multiple myeloma is another cause. Autoimmune diseases
, conditions in which a person's immune system attacks his or her
own body, can also cause kidney damage.
- blockage of urine flow, which commonly occurs with enlargement
of the prostate, also called benign prostatic hyperplasia
- taking certain medications, such as captopril or non-steroidal
anti-inflammatory drugs, or NSAIDs
A negative test means - Normal levels mean that kidney function
is normal, but do not mean that everything about the kidney is normal.