Creatinine
Names | |
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Preferred IUPAC name
2-Amino-1-methyl-5H-imidazol-4-one[citation needed] | |
Other names
2-Amino-1-methylimidazol-4-ol[citation needed]
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Identifiers | |
3D model (
JSmol ) |
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3DMet | |
112061 | |
ChEBI | |
ChEMBL | |
ChemSpider | |
DrugBank | |
ECHA InfoCard
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100.000.424 |
EC Number |
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KEGG | |
MeSH | Creatinine |
PubChem CID
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UNII | |
UN number | 1789 |
CompTox Dashboard (EPA)
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Properties | |
C4H7N3O | |
Molar mass | 113.120 g·mol−1 |
Appearance | White crystals |
Density | 1.09 g cm−3 |
Melting point | 300 °C (572 °F; 573 K)[1] (decomposes) |
1 part per 12[1]
90 mg/mL at 20°C[2] | |
log P | -1.76 |
Acidity (pKa) | 12.309 |
Basicity (pKb) | 1.688 |
Isoelectric point | 11.19 |
Thermochemistry | |
Heat capacity (C)
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138.1 J K−1 mol−1 (at 23.4 °C) |
Std molar
entropy (S⦵298) |
167.4 J K−1 mol−1 |
Std enthalpy of (ΔfH⦵298)formation |
−240.81–239.05 kJ mol−1 |
Std enthalpy of (ΔcH⦵298)combustion |
−2.33539–2.33367 MJ mol−1 |
Hazards | |
NFPA 704 (fire diamond) | |
Flash point | 290 °C (554 °F; 563 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Creatinine (/kriˈætɪnɪn, -niːn/; from Ancient Greek: κρέας (kréas) 'flesh') is a breakdown product of creatine phosphate from muscle and protein metabolism. It is released at a constant rate by the body (depending on muscle mass).[3][4]
Biological relevance
Serum creatinine (a blood measurement) is an important indicator of kidney health, because it is an easily measured byproduct of muscle metabolism that is excreted unchanged by the kidneys. Creatinine itself is produced[5] via a biological system involving creatine, phosphocreatine (also known as creatine phosphate), and adenosine triphosphate (ATP, the body's immediate energy supply).
Creatine is synthesized primarily in the liver from the methylation of
Creatinine is removed from the blood chiefly by the kidneys, primarily by
The GFR is clinically important as a measurement of
An alternative estimation of kidney function can be made when interpreting the blood plasma concentration of creatinine along with that of
Counterintuitively, supporting the observation of higher creatinine production in women compared to men, and putting into question the algorithms for GFR that do not distinguish for sex accordingly, women have higher muscle protein synthesis and higher muscle protein turnover across the life span.[9] As HDL supports muscle anabolism, higher muscle protein turnover links increased creatine to the generally higher serum HDL in women as compared to serum HDL in men and the HDL associated benefits like reduced incidence of cardiovascular complications and reduced COVID-19 severity.[10][11][12]
Antibacterial and potential immunosuppressive properties
Studies indicate creatinine can be effective at killing bacteria of many species in both the
Diagnostic use
Serum creatinine is the most commonly used indicator (but not direct measure) of
Serum creatinine
Diagnostic serum creatinine studies are used to determine renal function.[4] The reference interval is 0.6–1.3 mg/dL (53–115 μmol/L).[4] Measuring serum creatinine is a simple test, and it is the most commonly used indicator of renal function.[6]
A rise in blood creatinine concentration is a late marker, observed only with marked damage to functioning
A concern as of late 2010 relates to the adoption of a new analytical methodology, and a possible impact this may have in clinical medicine. Most clinical laboratories now align their creatinine measurements against a new standardized
A 2009 Japanese study found a lower serum creatinine concentration to be associated with an increased risk for the development of type 2 diabetes in Japanese men.[19]
Urine creatinine
Males produce approximately 150 μmol to 200 μmol of creatinine per kilogram of body weight per 24 h while females produce approximately 100 μmol/kg/24 h to 150 μmol/kg/24 h. In normal circumstances, all this daily creatinine production is excreted in the urine.
Creatinine concentration is checked during standard urine drug tests. An expected creatinine concentration indicates the test sample is undiluted, whereas low amounts of creatinine in the urine indicate either a manipulated test or low initial baseline creatinine concentrations. Test samples considered manipulated due to low creatinine are not tested, and the test is sometimes considered failed.
Interpretation
In the United States and in most European countries creatinine is usually reported in mg/dL, whereas in Canada, Australia,[20] and a few European countries, μmol/L is the usual unit. One mg/dL of creatinine is 88.4 μmol/L.
The typical human reference ranges for serum creatinine are 0.5 mg/dL to 1.0 mg/dL (about 45 μmol/L to 90 μmol/L) for women and 0.7 mg/dL to 1.2 mg/dL (60 μmol/L to 110 μmol/L) for men. The significance of a single creatinine value must be interpreted in light of the patient's muscle mass. Patients with greater muscle mass have higher creatinine concentrations.[citation needed]
The trend of serum creatinine concentrations over time is more important than absolute creatinine concentration.
Serum creatinine concentrations may increase when an ACE inhibitor (ACEI) is taken for heart failure and chronic kidney disease. ACE inhibitors provide survival benefits for patients with heart failure and slow the disease progression in patients with chronic kidney disease. An increase not exceeding 30% is to be expected with ACEI use. Therefore, usage of ACEI should not be stopped unless an increase of serum creatinine exceeded 30% or hyperkalemia develops.[21]
Chemistry
In chemical terms, creatinine is a lactam and an imidazolidinone, so a spontaneously formed cyclic derivative of creatine.[22]
Several tautomers of creatinine exist; ordered by contribution, they are:
- 2-Amino-1-methyl-1H-imidazol-4-ol (or 2-amino-1-methylimidazol-4-ol)
- 2-Amino-1-methyl-4,5-dihydro-1H-imidazol-4-one
- 2-Imino-1-methyl-2,3-dihydro-1H-imidazol-4-ol (or 2-imino-1-methyl-3H-imidazol-4-ol)
- 2-Imino-1-methylimidazolidin-4-one
- 2-Imino-1-methyl-2,5-dihydro-1H-imidazol-4-ol (or 2-imino-1-methyl-5H-imidazol-4-ol)
Creatinine starts to decompose around 300 °C.
See also
- Cystatin C, novel marker of kidney function
- Jaffe reaction, an example of creatinine assay methodology
- Rhabdomyolysis, may be diagnosed using creatinine levels
- Nephrotic syndrome
References
- ^ a b Merck Index, 11th Edition, 2571
- ^ "Creatinine, anhydrous - CAS 60-27-5". Scbt.com. Archived from the original on 2016-10-22. Retrieved 2016-10-21.
- ^ "Creatinine tests - Mayo Clinic". www.mayoclinic.org. Archived from the original on 2022-06-05.
- ^ OCLC 228373703.
- ^ "What Is a Creatinine Blood Test? Low & High Ranges". Medicinenet.com. Archived from the original on 21 September 2018. Retrieved 21 September 2018.
- ^ OCLC 19065010.
- PMID 22465051.
- PMID 2418254.
- PMID 18827019.
- S2CID 2050414.
- PMID 24170386.
- PMID 33785815.
- PMID 22293916.
- PMID 25093757.
- PMID 21575742.
- PMID 22745616.
- PMID 15616252.
- ^ "Carboplatin dosing". Center for Drug Evaluation and Research. Food and Drug Administration. Archived from the original on 2011-11-19.
- PMID 19074997.
- .
- S2CID 31459410.
- ^ "Creatinine". Archived from the original on 2022-04-09. Retrieved 2022-04-09.
External links
- Marshall W (2012). "Creatinine: analyte monograph" (PDF). The Association for Clinical Biochemistry and Laboratory Medicine. Archived from the original (PDF) on 14 June 2020.