Talk:Creatinine

message: for this phrase:
"A rise in blood creatinine level is observed only with marked damage to functioning nephrons. Therefore, this test is unsuitable for detecting early-stage kidney disease. A better estimation of kidney function is given by calculating the estimated glomerular filtration rate (eGFR). eGFR can be accurately calculated using serum creatinine concentration and some or all of the following variables: sex, age, weight, and race, as suggested by the American Diabetes Association without a 24-hour urine collection"
This doesn't make sense. The blood creatinine level is the basis of the eGFR, so the paragraph is contradicting itself. MG
For this phrase:
"While a baseline serum creatinine of 2.0 md/dL may indicate normal kidney function in a male body builder, a serum creatinine of 0.7 md/dL can indicate significant renal disease in a frail old woman."
A creatinine of 0.7 mg/dL is normal for a small frail woman.  A level of 2.0 mg/dL would indicate severe kidney disease in the old woman.  The more muscle mass you have, and the more you use those muscles, the more more creatinine you should excrete.  A frail old woman is expected to have very low creatinine levels. [[[Special:Contributions/24.250.22.201|24.250.22.201]] (talk) 19:22, 5 October 2008 (UTC)
replies: text: They are. Just a typo on my part. I've fixed it. Richardsur 23:36, 23 Aug 2004 (UTC)

message: Elevated creatinine levels due to supplemental creatine might result in mis-diagnosis.
Most doctors (general practitioners) appear unaware of creatine as a body building supplement.  They are apt to diagnose non-existent kidney conditions in healthy patients taking creatine supplements.  Mention should be made, under Diagnostic Use, of supplemental creatine as a possible source of elevated creatinine levels in healthy individuals.
Mseslacker 21:39, 4 March 2007 (UTC)
replies: text: No.  Creatinine is freely filtered at the glomerular apparatus.  While increased levels in a normal individual is a sign of impaired filtering, the increased creatinine does not harm or stress the kidneys in any way.  So, having a high level of creatinine is only a sign of a problem, but is not a problem.  Rjkd12 21:07, 5 December 2006 (UTC)
thread_title:  Sports medicine 

message: why high levels cause leg cramps?
what is the pathophysiological reason for this? including some biochem rxn reasons or molec cell explanations.  Why in the legs and not other places? what about joint problems? what is causing the muscle pain?  And then, shouldn't there be better linking to diseases and treatments to kidney problems?
:Creatinine nor creatine causes cramps.  This is one of the oldest myths around.  Cramps are neurological in nature and have to do with muscle spindles and golgi tendon organs.  
:It is also freely filtered at the glomerular apparatus, so it doesn't "stress" the kidneys to excrete large amounts, nor is high levels bad at all.  A high urniary creatinine level is no more indicative of renal failure than urinating a lot for a few days is indicative of having diabetes.  Rjkd12 16:21, 28 February 2007 (UTC)
thread_title: why leg cramps?

message: If anyone needs it for a later infobox, Creatinine's SMILES formula is CN1CC(=O)NC1=N.  That's C4H7N3O, a molecular weight of about 113.  71.41.210.146 00:45, 2 May 2007 (UTC)
thread_title:  [[SMILES]] formula 

message: This page says:
:Vegetarians tend to have lower creatinine levels, because vegetables contain no creatinine.
This is contradicted on WebMD: 
:Creatinine is made at a steady rate and is not affected by diet or by normal physical activities.
:http://www.webmd.com/a-to-z-guides/creatinine-and-creatinine-clearance  —Preceding unsigned comment added by 24.188.141.76 (talk) 00:04, 23 April 2008 (UTC)
replies: text: I've found a 1989 study in which creatinine levels of vegetarians and non-vegetarians were compared. I've added the citation to the above statement. Temporal User (Talk) 01:58, 2 March 2009 (UTC)
thread_title: potential inaccuracy

message: There is a reference range with a nonzero lower bound, but the article talks only about the meaning of high values, not low ones.  Perhaps add a sentence about that?  Thanks. Briankharvey (talk) 23:27, 14 December 2020 (UTC)
thread_title:  What does low creatinine mean? 

message: Some of the chemical information in the article is questionable, including the (unreferenced, but ranked) list of named tautomers and some of the structures and names in the linked external datasets listed in the Chemical Infobox.  Also, the article does not cover recent publications.  An update of the Chemistry section might include:
There are eight possible structures for creatinine, including geometric isomerism of the 2-imino tautomers, although enolic forms are significantly less stable than their ketonic counterparts and can be discounted.  Only the amine tautomer of creatinine has been experimentally characterized in polar solvents or the solid state, while both imine and amine tautomers have been observed in gasphase spectroscopic studies.
The general statement that creatinine tautomers are in equilibrium is not really accurate under normal conditions.  In aqueous environments, both hydrogen bonding with the inner solvation-shell of water molecules and overall polar-solvent effects stabilise the amino form, with pH also having a significant effect [with high pH increasing ring cleavage to (re)form creatine].  Thus amine-imine tautomerism may not be relevant in a biological context (other than in possible mechanistic routes) and keto-enol tautomerism probably can be disregarded.
The Wikipedia article on Tautomers covers  implications for databases, noting the advantages of notation, but this leaves the problem of nomenclature if Creatinine is to be named systematically, since such names are specific to a single structure.  Fortunately, on the basis of the above (but not the existing article), it seems reasonable to base the preferred name on the amine structure.  Unfortunately, the quality of structural and naming information for Creatinine in the Chemical Infobox and some of the external databases listed is variable, to put it politely and in the light of the text proposed above.  To enumerate the points:
# IUPAC Preferred Name: Naming of the parent cycle of the 2-amino-4-one and 2-imino-4-one tautomers differs because in the former the ring contains unsaturation, whereas in the latter it is saturated (but with conjugation through the 3-N lone pair), resulting in the stems "diazole" and "diazolidine", respectively, under  Hantzsch–Widman rules. In the 2-amino structure, the partial ring saturation is reflected by indicated hydrogen (xH) and "dihydro" terms, with appropriate locants.
# Whether "Other names" should just include variants for the 2-amino structure or also for the 2-imino structure is a moot point.
# CHEBI:16737 and CHEMBL65567 (Creatinine) give the structure and names of the 2-imino form, as does DrugBank DB11846 and KEGG D03600.
# ChemSpider 21640982 (Creatinine) gives the structure and names of the 2-amino-4-hydroxy compound with a doubly unsaturated diazolidine ring.
# ECHA InfoCard	100.000.424 and EC number: 200-466-7 use 2-imino-1-methylimidazolidin-4-one as the heading for Creatinine.
# MeSH term Creatinine (D003404) - sanity at last!
# PubChem CID 26009888 is 2-amino-1-methyl-1H-imidazol-4-ol, an isomer of Creatinine, but according to the reference cited above not a significant tautomer.  The PubChem CID for Creatinine is 588; it supplies the 2-amino-4-one structure, but includes the 2-imino form amongst the list of synonyms.  It was the illogically of calling Creatinine a minor tautomer of Creatinine that originally suggested that there might be problems in the information for the compound.
# UNII: AYI8EX34EU uses the 2-amino structure, but supplies some 2-imino names.  The linked Inxight Drugs database has the 2-amino structure but gives 2-Imino-1-methylimidazolidin-4-one as the "Systematic Name", relegating 2-amino names to "Common Name"s!
# CompTox Dashboard (EPA) DTXSID8045987 shows the 2-imino structure and provides "IUPAC Name: 2-Imino-1-methylimidazolidin-4-one".
This seems an unsatisfactory situation for the information on a biologically significant compound, with it being unclear why databases prefer a structure that is not normally observed in reality.  Is this really the case and what should be done about it? Douglian30 (talk) 16:33, 19 August 2023 (UTC)
thread_title:  Tautomers and nomenclature 

message: At one point in the article, it claims that women produce more creatinine than men, but then later on it gives statistics that seem to contradict this (even when measured proportionately to body weight, the statistics say men produce more). What’s going on here? 2600:1014:B081:E2B1:9CF0:D3EC:3C4D:BA57 (talk) 02:40, 15 December 2023 (UTC)
thread_title: Men vs. women