Social Security is required to show that a medical condition causing a disability has produced medical improvement expected before terminating benefits due a claimant. Substantial evidence that there has been medical improvement in the condition, and evidence that the claimant is now able to work and in certain circumstances benefits may also be terminated even if the claimant remains unable to work. Medical improvement is defined as any decrease in the medical severity of the beneficiary's condition on the basis of changes in symptoms and laboratory tests since the most recent favorable medical report.