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

In a large international analysis, more than one third of hospitalized patients had cystatin C results that suggested kidney function was at least 30% worse than what their creatinine levels indicated.

From Science Daily • Jan. 21, 2026

“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

The approach, based on US studies dating to 1999 that found higher average creatinine levels in people of black and African American heritage, was inappropriate to apply to European black populations, Dr Bramham said.

From BBC • Nov. 28, 2022

For decades, the kidney function formula has involved measuring blood levels of creatinine — a waste product produced by muscles.

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