In 1957 Black-Schaffer proposed a unitary explanation that stress on the ventricle, of any kind, may trigger the endocardial reaction, so that all EFE could be thought of as secondary.Evidence gradually accumulated as to the role of infection as one such type of stress. The studies of Fruhling and colleagues in 1962 were critical. They followed a series of epidemics of Coxsackie virus infection in their part of France. After each epidemic there were increased numbers of cases with EFE coming to autopsy. On closer study there were cases of pure acute myocarditis, cases of mixed myocarditis and EFE, and cases where myocarditis had healed, leaving just EFE. They were able to culture Coxsackie virus from the tissues of many of the cases at all stages  of this apparent progression. A similar progression from myocarditis to EFE was later observed at Johns Hopkins but no virology was done.Noren and colleagues at the University of Minnesota, acting on an idea floated at a pediatric meeting, were able to show a relation between exposure to maternal mumps in fetal life, EFE, and a positive skin test for mumps in infants. This brought on a large ongoing controversy and finally prompted a virologist colleague of theirs to inject embryonated eggs with mumps virus. The chicks at first showed the changes of myocarditis, about a year later, typical EFE, and transitional changes in between. Despite this, the controversy about the role of mumps continued as the actual incidence of EFE plummeted.
Two types of blood tests are used to confirm the presence of a hormone deficiency: basal levels, where blood samples are taken–usually in the morning–without any form of stimulation, and dynamic tests, where blood tests are taken after the injection of a stimulating substance. Measurement of ACTH and growth hormone usually requires dynamic testing, whereas the other hormones (LH/FSH, prolactin, TSH) can typically be tested with basal levels. There is no adequate direct test for ADH levels, but ADH deficiency can be confirmed indirectly; oxytocin levels are not routinely measured.Generally, the finding of a combination of a low pituitary hormone together with a low hormone from the effector gland is indicative of hypopituitarism. Occasionally, the pituitary hormone may be normal but the effector gland hormone decreased; in this case, the pituitary is not responding appropriately to effector hormone changes, and the combination of findings is still suggestive of hypopituitarism. Basal tests
Levels of LH/FSH may be suppressed by a raised prolactin level, and are therefore not interpretable unless prolactin is low or normal. In men, the combination of low LH and FSH in combination with a low testosterone confirms LH/FSH deficiency; a high testosterone would indicate a  source elsewhere in the body (such as a testosterone-secreting tumor). In women, the diagnosis of LH/FSH deficiency depends on whether the woman has been through the menopause.