The 99th percentile of reference population for cTnI and cTnT assay: Methodology, pathophysiology and clinical implications

According to recent international guidelines, including the 2012 Third Universal Definiton of Myocardial Infarction by the Joint ESC/ACCF/AHA/WHF Task Force, an increase in cardiac troponin (cTn) levels over the 99th percentile upper reference limit (99th URL) should be considered clinically relevant, this cut-off being measured with an imprecision â\u89¤10 CV%. In theory 99th URL values strongly depend not only on demographic and physiological variables (i.e. criteria for considering the reference population "healthy"), but also on the analytical performance of cTn methods and mathematical algorithms used for the calculation. The aim of the present article was therefore to review the methodological and pathophysiological factors affecting the evaluation and calculation of the 99th URL for cTn assay. The critical analysis made showed that no uniform procedure is followed, and nor have experts or regulatory bodies provided uniform guidelines for researchers or cTn assays manufacturers as an aid in "their quest to define normality". In particular, little attention has been paid to the way in which a healthy reference population is to be selected, or the criteria for calculating the 99th URL value for cTn assays, thus highlighting the need for international recommendations not only for demographic and physiological variables criteria for defining a healthy reference population, but also for calculating mathematical algorithms for establishing/calculating clinical decision values. An expert consensus group, comprising laboratory and clinical scientists, biomedical statisticians, industrial and regulatory representatives, should be responsible for drawing up these guidelines

Why we might not need to stress about ruling out inducible myocardial ischemia

Editorial on the high-sensitivity cardiac troponin (hs-cTn) tests

Cardiac troponin I but not cardiac troponin T adheres to polysulfone dialyser membranes in an in vitro haemodialysis model: explanation for lower serum cTnI concentrations following dialysis.

BACKGROUND: Elevated serum cardiac troponin T (cTnT) and I (cTnI) can occur in patients with chronic kidney disease. Differences in cTn concentrations between cTnT and cTnI have been reported but the mechanism of such discrepancy has not been investigated. This study investigates the clearance of cTn with the aid of an in vitro model of haemodialysis (HD). METHODS: Serum was obtained before and after a single session of dialysis from 53 patients receiving HD and assayed for cTnT and cTnI. An in vitro model of the dialysis process was used to investigate the mechanism of clearance of cTn during HD. RESULTS: Serum cTnI was significantly lower (p=0.043) following a session of HD whereas cTnT concentrations were similar to those obtained before HD. Using an in vitro model of dialysis, it was demonstrated that cTnI is not dialysed from the vascular compartment but adheres to the dialyser membrane. CONCLUSIONS: The adherence of cTnI to the dialyser membrane is responsible for the observed decrease in serum cTnI following a session of dialysis. The adherence of cTnT or T-I-C complex to the dialyser membrane could not be demonstrated and supports the observation that pre-HD and post-HD serum concentrations of cTnT are similar

Combination of pharmacotherapy and lidocaine analgesic block of the peripheral trigeminal branches for trigeminal neuralgia: a pilot study

Classical trigeminal neuralgia (CTN) is treated predominantly by pharmacotherapy but side effects and unsuccessful occurs. The current study was carried out to evaluate the therapeutic effect of combination of pharmacotherapy and lidocaine block. Thirteen patients with CTN managed with pharmacotherapy were recruited and assigned either to no additional treatment (Group I) or to additional analgesic block (Group II). The primary endpoint was the reduction in the frequency of pain episodes in a month assessed at 30 and 90 days. Comparisons of measurements of pain, general health and depression scales were secondary endpoints. The results from the follow-up visits at 30 and 90 days showed the Group II to have larger reduction in the frequency of pain and exhibited a bigger improvement in the scores of the pain, general health and depression scales. The results from this preliminary study suggest a clinical benefit of the combination of pharmacotherapy and lidocaine block

Vereseerumi troponiini määramine erakorralises meditsiinis

Troponiinide (Tn) määramine on erakorralise meditsiini osakonnas (EMO) laialdaselt kasutusel, seda ennekõike ägedate koronaarsündroomide (ÄKS) diagnoosimiseks ja välistamiseks. Nüüdseks on kasutusel testid, mis on tuntud kui kardiaalse troponiini (cTN) määramise kõrgtundlikud testid (ingl high-sensitive cardiac troponin, hs-cTn). Nende testidega on võimalik sedastada vereseerumis juba minimaalne troponiinisisaldus. Paraku on suurem tundlikkus toonud kaasa testi vähenenud spetsiifilisuse. On tekkinud olukord, kus haigetel leitakse üha sagedamini cTn referentväärtust ületavaid tulemusi, kuid samal ajal puudub otsene südamekahjustusele viitav seisund või haigus. On kirjeldatud mitmeid erinevaid haigusseisundeid, millega seostatakse troponiinide sisalduse suurenemist, kuid selle kliiniline tähtsus pole alati üheselt selge.Eesti Arst 2016; 95(8):515–52

Evidence of descending inhibition deficits in atypical but not classical trigeminal neuralgia

Abstract : Trigeminal neuralgia (TN) is a rare neuropathic facial pain disorder. Two forms of TN, classical TN (CTN) and atypical TN (ATN), are reported and probably have different aetiologies. The aim of the present study was to evaluate the functional integrity of the diffuse noxious inhibitory controls (DNIC) in (1) a group of patients with classical trigeminal neuralgia (CTN), (2) a group of patients with atypical trigeminal neuralgia (ATN), and (3) a group of healthy controls in order to determine if a descending pain modulation deficit could participate in the pathophysiology of TN pain. DNIC responses of 14 CTN patients, 14 ATN patients and 14 healthy controls were obtained by comparing thermode-induced facial heat pain scores before and after activating DNIC. DNIC was triggered using a standard counter-irritation paradigm (i.e., immersion of the arm in painfully cold water). General sensitivity to pain was also evaluated by measuring mechanical pain thresholds over 18 points located outside the trigeminal territory. Healthy participants and CTN patients showed a 21% and 16% reduction in thermode-induced pain following the immersion, respectively (all p-values <.01), whereas ATN patients experienced no change (p=.57). ATN patients also had more tender points (mechanical pain thresholds < 4.0 kg) than CTN and healthy controls (all p-values < .05). Taken together, these results suggest that the underlying physiopathology differs between CTN and ATN and that a deficit in descending inhibition may further contribute to the pain experienced by patients with ATN