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Background Elevated troponin T and/or troponin I can be ascribed to multiple causes, mostly resulting from cardiac tissue damage and in lesser numbers resulting from non-cardiac related causes. The presence of macrotroponins is easily overlooked with potentially negative consequences. Case Summary This case report presents a case study of a 12 year old child known to have a MYH7-gene associated hypertrophic cardiomyopathy with acute chest pain combined with an unexpected high troponin T and I. A cardiac cause was deemed unlikely after additional investigation, as these showed no abnormalities. After consulting the laboratory specialist it could be concluded that the high troponin T and I were a result of macrotroponin complexes, a protein complex consisting of circulating protein and endogenous autoantibodies against that protein, resulting in elevated values with misguiding and uncertain clinical significance. Discussion Awareness of the existence of macrotroponins could have prevented costly diagnostics and prolonged hospital admission with grave psychological impact, especially in children.