Possible causes
Various different causes for MCS have been hypothesized.There is a general agreement among most MCS researchers that the cause is not specifically related to sensitivity to chemicals, but this does not preclude the possibility that symptoms are caused by other known or unknown factors. Various health care professionals and government agencies are working on giving those who report the symptoms proper care while searching for a cause.In 2017, a Canadian government Task Force on Environmental Health said that there had been very little rigorous peer-reviewed research into MCS and almost a complete lack of funding for such research in North America. "Most recently," it said, "some peer-reviewed clinical research has emerged from centres in Italy, Denmark and Japan suggesting that there are fundamental neurobiologic, metabolic, and genetic susceptibility factors that underlie ES/MCS. "The US Occupational Safety and Health Administration (OSHA) says that MCS is highly controversial and that there is insufficient scientific evidence to explain the relationship between any of the suggested causes of MCS – it lists "allergy, dysfunction of the immune system, neurobiological sensitization, and various psychological theories" as the suggested causes – and its symptoms. Immunological
Researchers have studied immunity biomarkers in people with MCS to determine whether MCS could be an autoimmune disorder or allergic response, but the results have been inconclusive. Some people with MCS appear to have excess production of inflammatory cytokines, but this phenomenon is not specific to MCS and overall there is no evidence that low-level chemical exposure causes an immune response.
Risk scores
The Global Registry of Acute Coronary Events score and the Thrombosis in Myocardial Infarction performed at time of admission may help stratify persons into low, intermediate and high risk groups for acute coronary syndrome. However these scores do not provide management guidelines for risk-stratified persons. The HEART score, stratifies persons into low-risk and high-risk groups, and recommends either discharge or admission based upon the score. Cumulative score:

0-3: 2.5% risk of adverse cardiac event. Patients can be discharged with follow-up. 4-6: 20.3% risk of adverse cardiac event. Patients should be admitted to the hospital for trending of troponin and provocative testing. ≥7: 72.7% risk of adverse cardiac event, suggesting early invasive measures with these patients and close coordination with inpatient cardiology.If acute coronary syndrome ("heart attack") is suspected, many people are admitted briefly for observation, sequential ECGs, and measurement of cardiac enzymes in the blood over time. On occasion, further tests on follow up may determine the cause.