creatinine

American  

[kree-at-n-een, -in] / kriˈæt nˌin, -ɪn /

noun

Biochemistry.

1. a crystalline end product of creatine metabolism, C 4 H 7 N 3 O, occurring in urine, muscle, and blood.

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creatinine British  

/ kriːˈætəˌniːn /

noun

1. an anhydride of creatine that is abundant in muscle and excreted in the urine

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creatinine Scientific  

/ krē-ăt′n-ēn′,-ĭn /

1. A compound formed by the metabolism of creatine, found in muscle tissue and blood and normally excreted in the urine as a metabolic waste. Measurement of creatinine levels in the blood is used to evaluate kidney function. Chemical formula: C ₄ H ₇ N ₃ O.

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Etymology

Origin of creatinine

First recorded in 1850–55; from German Kreatinin, equivalent to kreatin creatine ( def. ) + -in -ine ² ( def. )

Compare meaning

How does creatinine compare to similar and commonly confused words? Explore the most common comparisons:

• creatine vs. creatinine

Example Sentences

For many years, doctors have relied on a blood marker called creatinine to estimate how well the kidneys filter waste produced by muscle activity.

From Science Daily • Jan. 21, 2026

Doctors at the hospital said Anirudh's kidneys were damaged, and that levels of creatinine - a waste product normally filtered out by the kidneys - were very high in his body.

From BBC • Sep. 3, 2023

“The really new finding here is that these pig kidneys can clear enough creatinine to support an adult human,” Dr. Locke said.

From New York Times • Aug. 16, 2023

Higher creatinine levels suggest that the kidneys are struggling, translating into a lower kidney-function score.

From Seattle Times • Apr. 22, 2022

Reluctantly, he acquiesced; the test showed that he suffered from elevated levels of serum creatinine with a value way above 1.4, the highest parameter in the normal range.

From "Endgame" by Frank Brady