High sensitivity(HS) troponin measurement in the emergency room/hospital setting is now widely established in Australia and is now being recommended for widespread implementation in the USA. Lower cut-offs into the normal range may find value as a single determinant for exclusion purposes in the acute emergency ward setting, however, because HS troponin may be elevated in a number of noncoronary cardiac conditions, a rise and/or fall in the level is usually required for diagnosis of a coronary infarct¹. In unstable angina pectoris, a troponin level may be normal, as may an ECG recording if the patient is pain free at the time. Two articles in the Medical Journal of Australia published in the past three years have addressed the issues/problems surrounding ordering of the test in general practice ^1,2. In both articles the authors agree that there are times when a single measurement of HS troponin can be useful clinically; however, there are times when it can be counterproductive. Firstly, it is agreed that a patient with classical features of the acute coronary syndrome (ACS) plus or minus ECG findings who has had pain in the 24 hours prior to assessment should be referred urgently to an emergency centre without troponin measurement. The turnaround time for an urgent troponin in most acute hospitals is of the order of 60 minutes or less. In the community private pathology scenario, turnaround time for a troponin result, even when treated as urgent, could take anywhere from four to 12 hours. That usually means that the result is only available after hours. Frequently, the ordering clinician is unavailable to receive or act on the result. A troponin can be useful in the general practice setting if the patient has had atypical chest pain with a low but not negligible likelihood of ACS; or if the patient has been pain and symptom free for 24 hours with a normal ECG. After an infarct, troponin can remain elevated for over a week. For the laboratory, an abnormal troponin requires phoning the result if it is an urgent request from the clinician. This may be after hours – even after midnight. Usually the context of the result is only known by the requesting clinician. If a requesting clinician is unavailable to receive the result after hours, the patient will usually be contacted by a pathologist or emergency services. After-hours doctor services often are uninterested in receiving or acting on critical results such as troponin. In summary, there is a place for troponin measurement in general practice. Elevated levels are not uncommon due to causes other than the ACS. Turnaround time for a result may take much longer when collected in a collection centre than in the hospital setting. When ordering an urgent troponin please ensure that the laboratory has a valid contact number for after hours. References 1. Aroney CA, Cullen L. Appropriate use of serum troponin testing in general practice: a narrative review. MJA 2016; 205:(2) 91-94. 2. Marshall GA, Wijeratne NG, Thomas D. Should general practitioners order troponin tests? MJA 2014; 201: 155-157.

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General Practice Pathology is a new regular column each authored by an Australian expert pathologist on a topic of particular relevance and interest to practising GPs. The authors provide this editorial, free of charge as part of an educational initiative developed and coordinated by Sonic Pathology.