Troponin question

[GiJoe]

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an intern and I were talking about a pt he had...she was a lady with a hx of multi organ transplant who was going into renal failure who came in with "stabbing chest pain" radiating to her back... EKG showed diffuse ST elevation... he initially thought pericarditis, but then her troponin came back and it was 7. he called the cath lab and instead oftaking her upstairs, 2 cardio fellows came down and were doing an echo... it turned out she had an effusion...

what confused both of us was that since her troponin was elevated. isn't the elevation of troponin specific for infarction of istriated muscle fibers in the myocardium....? or are there other situations besides MI where troponin can be elevated?

 

[rpkall]

I was just poking around and found this little summary about this issue: http://sitemaker.umich.edu/emjournalclub/article_database/da.data/53943/PDF/pericarditits_troponin_jacc.pdf#search='effusion%20AND%20troponin'.
From the JACC, 2003.


I guess there can be some cardiac muscle damage in idiopathic acute pericarditis; you would think this would correlate with a large effusion (compression ischemia) or a loud friction rub or something, but it doesn't look crazy-likely, based on the mini-review in the discussion. They've used troponins as a marker of cardiac damage in myocarditis, PE, and CHF, it looks like... Probably not standard at most hospitals though.

Help any?

 

[southerndoc]

Troponins are sensitive for cardiac ischemia, but not specific. Constrictive pericardial effusions can induce areas of ischemia by compressive forces limiting blood perfusion to certain areas of the heart. Likewise, pulmonary emboli can cause such severe right ventricular strain to cause right ventricular ischemia. All of these conditions can induce elevated troponins.

 

[DrQuinn]

Troponins are sensitive for cardiac ischemia, but not specific. Constrictive pericardial effusions can induce areas of ischemia by compressive forces limiting blood perfusion to certain areas of the heart. Likewise, pulmonary emboli can cause such severe right ventricular strain to cause right ventricular ischemia. All of these conditions can induce elevated troponins.

Agree. There was an article in "Chest" about two years ago that had this big ass list of everything that caused an elevated troponins. The first thing that SHOULD pop into your head is myocardial ischemia but its not hte only thing.

That being said, there is no "troponin leak" in renal patients. We used to get the medicine residents balking at raised troponins in ESRDs, saying it was secondary to their renal failure. There was a study a year or so ago... can't remember which journal, but they measured troponins before and after dialysis... they should always be negative.

Q

 

[NinerNiner999]

As Quinn suggested, wouldn't a Troponin of 7 be a little more than a "leak" if dealing with myocardial ischemia? We get concerned about troponins slightly above 0.07 in non-renal patients. Was there a relatively low CK-MB index that correlated with echo versus cath? Was the patient in tamponade from exceedingly high pericardial pressure secondary to effusion? I would think symptomatic pericardial effusion would become symptomatic (hypotension, JVP, etc) long before a troponin would bump. It sounds like the ECHO was performed more to estimate EF and check for wall motion abnormalitiy compared to previous, given the patient's renal history (acute change in either would suggest myocardial damage and go to cath). Perhaps the effusion was an incidental finding...

 

[DrDre']

I thought troponin was elevated in ESRD because the renal clearance was impaired, is this not believed correct?

Troponin bumps with a million things. the article cited above is a quick read and interesting.

 

[DrDre']

Sorry. didn't read Quinn's Chest (Back when we thought he was a she, I wish I had 🙂), article.

This one is good:
Jeremias Am Gibson CM, Narrative review: alternative causes for elevated cardiac troponin levels when ACS are excluded. Ann Intern Med. 2005;142:786-791.

 

[Seaglass]

With regards to troponin of 7, different hospitals use different assays, and a 7 could be a very low value on one assay and a moderately high value on another.

 

[aliraja]

Agree. There was an article in "Chest" about two years ago that had this big ass list of everything that caused an elevated troponins.

Q

Here's the link. I was reading this thing just a few days ago and knew I had it around here somewhere:

http://www.chestjournal.org/cgi/content/full/125/5/1877

 

[mikecwru]

Agree. There was an article in "Chest" about two years ago that had this big ass list of everything that caused an elevated troponins. The first thing that SHOULD pop into your head is myocardial ischemia but its not hte only thing.

That being said, there is no "troponin leak" in renal patients. We used to get the medicine residents balking at raised troponins in ESRDs, saying it was secondary to their renal failure. There was a study a year or so ago... can't remember which journal, but they measured troponins before and after dialysis... they should always be negative.

Q

You have to be careful with the terms:

Troponin rise is causes by myocardial infarction. Period.

If I stab you in the chest and cause a piece of your heart muscle to die, your troponin could rise.

However, myocardial ischemia/infarction does not imply necessarily what we think of when we sling the term "MI" --- which is ACS, the traditional thought of a plaque rupture leading to thrombus formation, showing a current of injury in a coronary artery distribution.

You can infarct from ACS or from the plethora of things everyone is mentioning... ventricular strain, severe anemia, etc.

mike

 

[KGUNNER1]

You have to be careful with the terms:

Troponin rise is causes by myocardial infarction. Period.

If I stab you in the chest and cause a piece of your heart muscle to die, your troponin could rise.

However, myocardial ischemia/infarction does not imply necessarily what we think of when we sling the term "MI" --- which is ACS, the traditional thought of a plaque rupture leading to thrombus formation, showing a current of injury in a coronary artery distribution.

You can infarct from ACS or from the plethora of things everyone is mentioning... ventricular strain, severe anemia, etc.

mike

Exactly. Troponin is only released from dead cardiac myocytes. It doesn't tell us HOW or WHY they died. Cytotoxins such as TNF-alpha, IL-1, IL-6 contribute to this in sepsis; many others do as well.

The problem comes when we are so used to equating cardiac myocyte death with MACROvascular disease (occluded LAD) that requires an intervention (PTCA).

However, a large number of these myocyte deaths occur in the presence of normal coronary MACROarteries, however there may be microvascular abnormalities or circulating toxins causing myocardial depression and/or death. Thus you have elevated troponin with a normal Cath. Happens around 15-20% of the time in patients with severe sepsis.

kg

 

[dlung]

I just had a patient who's walking around with a baseline trop level of 1-ish. Never could figure out the etiology.

 

[tonem]

This has been driving me crazy for a couple of years because I got tired of cardiology fellows saying it's only a Troponin, leak discharge em home when I always thought troponin equaled dead myocytes. I've never did find any primary literature that said Troponin is absolutely only released by dead myocytes...most recently I did read something that said anything that causes ischemia can cause an elevation in troponin as can ESRD or CRI....unfortunately I can't find the reference now....so if you guys that are proponents of the "only dead myocytes" cause elevated troponins could point me in the right direction for that literature.....I'd appreciate it.

 

[southerndoc]

The concept of a troponin leak does NOT underplay ischemia as the cause. Troponin doesn't only result from dead myocytes. As ischemia occurs, the cardiac myocytes cannot keep up with demand for ATP, which causes Na-K pumps to begin to fail. In addition, ATP is required to release myocardial contraction through the actin-myosin interactions, of which troponin is a component. Without ATP, troponin "leaks" because of disruptions in cell membrane integrity from lack of the sodium-potassium pump.

There is cellular edema associated with ischemia, but there is not necessarily a cell lysis.

 

[leviathan]

This has been driving me crazy for a couple of years because I got tired of cardiology fellows saying it's only a Troponin, leak discharge em home when I always thought troponin equaled dead myocytes. I've never did find any primary literature that said Troponin is absolutely only released by dead myocytes...most recently I did read something that said anything that causes ischemia can cause an elevation in troponin as can ESRD or CRI....unfortunately I can't find the reference now....so if you guys that are proponents of the "only dead myocytes" cause elevated troponins could point me in the right direction for that literature.....I'd appreciate it.

From what I understand, Troponin I does not rise from chronic renal failure, however the other subtypes may differ in their specificity.

 

[ERMudPhud]

I just had a patient who's walking around with a baseline trop level of 1-ish. Never could figure out the etiology.

So here is one cause of an elevated troponin that doesn't come from myocytes and isn't actually "troponin".

Troponin like a number of other protein/enzyme assays is often but not always done as an antibody sandwich assay. You have one antibody immobillized to a matrix that binds to troponin. You have a second antibody that binds to troponin and has some detectable marker attached to it (an enzyme, a flourescent molecule, whatever) You measure troponin by the amount of that second antibody that binds to the first assuming that troponin is bridging the two (the filling in the sandwich). Well what if you have something else in your serum that can nonspecifically bind two antibodies together? Rheumatoid factors are anti-Ig antibodies so if you have a high enough RF titer you can get a false positive elevated troponin. Your level may fluctuate based on your RF titer but it is often chronically up.

 

[Crypt Abscess]

Interesting MudPhud- I had never heard of elevated RF causing false + TnI elevations.

I agree with Case- elevated troponin means infarction (which of course, as we all know is caused by ischemia)

As an IM resident who has done several months of CCU and Cardiology- we are frequently consulted from many different services for Troponin bumps.

We always call the troponin bump- "Non-ACS myonecrosis" I think this is the most appropriate term, and I think this is the term either Wash Manual or some other Cards referefence book calls this.

Good discussion.

 

[ERMudPhud]

Interesting MudPhud- I had never heard of elevated RF causing false + TnI elevations.

Just in case anyone gets pimped on this here are the references. Realize though that they don't all reach the same conclusion about whether the interference exists and whether the mechanism is as I stated.

1: Kenny PR, Finger DR.
Falsely elevated cardiac troponin-I in patients with seropositive rheumatoid
arthritis.
J Rheumatol. 2005 Jul;32(7):1258-61.
PMID: 15996061 [PubMed - indexed for MEDLINE]

2: Bas S, Genevay S, Mensi N.
False positive elevation of cardiac troponin I in seropositive rheumatoid
arthritis.
J Rheumatol. 2002 Dec;29(12):2665. No abstract available.
PMID: 12465175 [PubMed - indexed for MEDLINE]

3: Knoblock RJ, Lehman CM, Smith RA, Apple FS, Roberts WL.
False-positive AxSYM cardiac troponin I results in a 53-year-old woman.
Arch Pathol Lab Med. 2002 May;126(5):606-9.
PMID: 11958670 [PubMed - indexed for MEDLINE]

4: Lefevre G, Graine H, Bakkouch K, Garbarz E, Marlin G, Michel PL, Capeau J.
Evaluation of kryptor cardiac troponin I immunoassay.
Ann Clin Biochem. 2002 Mar;39(Pt 2):145-7.
PMID: 11928763 [PubMed - indexed for MEDLINE]

5: Katwa G, Komatireddy G, Walker SE.
False positive elevation of cardiac troponin I in seropositive rheumatoid
arthritis.
J Rheumatol. 2001 Dec;28(12):2750-1.
PMID: 11764229 [PubMed - indexed for MEDLINE]

6: Lewis JS Jr, Taylor JF, Miklos AZ, Virgo KS, Creer MH, Ritter DG.
Clinical significance of low-positive troponin I by AxSYM and ACS:180.
Am J Clin Pathol. 2001 Sep;116(3):396-402.
PMID: 11554168 [PubMed - indexed for MEDLINE]

7: Banerjee S, Linder MW, Singer I.
False-positive troponin I in a patient with acute cholecystitis and positive
rheumatoid factor assay.
Cardiology. 2001;95(3):170-1. No abstract available.
PMID: 11474166 [PubMed - indexed for MEDLINE]

8: Krahn J, Parry DM, Leroux M, Dalton J.
High percentage of false positive cardiac troponin I results in patients with
rheumatoid factor.
Clin Biochem. 1999 Aug;32(6):477-80. No abstract available.
PMID: 10667485 [PubMed - indexed for MEDLINE]

9: Onuska KD, Hill SA.
Effect of rheumatoid factor on cardiac troponin I measurement using two
commercial measurement systems.
Clin Chem. 2000 Feb;46(2):307-8. No abstract available.
PMID: 10657400 [PubMed - indexed for MEDLINE]

10: Zaman Z, De Spiegeleer S, Gerits M, Blanckaert N.
Analytical and clinical performance of two cardiac troponin I immunoassays.
Clin Chem Lab Med. 1999 Sep;37(9):889-97.
PMID: 10596955 [PubMed - indexed for MEDLINE]

11: Clark GH, Kennon SR, Price CP.
Evaluation of a new troponin I method on the Bayer Immuno 1 immunoassay
analyser.
J Immunoassay. 1999 Nov;20(4):253-73.
PMID: 10595858 [PubMed - indexed for MEDLINE]

12: Dasgupta A, Banerjee SK, Datta P.
False-positive troponin I in the MEIA due to the presence of rheumatoid factors
in serum. Elimination of this interference by using a polyclonal antisera
against rheumatoid factors.
Am J Clin Pathol. 1999 Dec;112(6):753-6.
PMID: 10587696 [PubMed - indexed for MEDLINE]

 

[toughlife]

an intern and I were talking about a pt he had...she was a lady with a hx of multi organ transplant who was going into renal failure who came in with "stabbing chest pain" radiating to her back... EKG showed diffuse ST elevation... he initially thought pericarditis, but then her troponin came back and it was 7. he called the cath lab and instead oftaking her upstairs, 2 cardio fellows came down and were doing an echo... it turned out she had an effusion...

what confused both of us was that since her troponin was elevated. isn't the elevation of troponin specific for infarction of istriated muscle fibers in the myocardium....? or are there other situations besides MI where troponin can be elevated?

When I was doing my medicine clerkship, I had a patient with ESRD on HD who had an elevated troponin as baseline. One time he complained of chest pain and we ordered cardiac enzymes and his troponin was elevated so we admitted him to the ICU. As an idiot, I forgot to check his baseline troponin. If had done that, I would have known that it was his baseline and would have saved me an ICU admission.

 

[Sessamoid]

I've yet to meet a dialysis patient who didn't have at least an intermediate troponin level as a baseline. And yes, that's always been troponin I. Does any hospital even to troponin T assays anymore?

 

[rksria]

Hello, I am a medical student from Indonesia. This is my first post on SDN. I want to make a research on the relationship area of ​​cardiac infarction with the levels of troponin T. Do you think is true whether troponin T levels are associated with an wide area of cardiac infarction?

 

[tkim]

Here let me help you:

http://www.ncbi.nlm.nih.gov/pubmed/

 

[GoSpursGo]

I'm going to let this thread die again since you posted the same question in another forum; please don't post the same question in multiple forums.