Local coverage determination (LCD) policies issued by Medicare administrative contractors (MACs) serve as the workhorse of Medicare coverage policy. About 90 percent of coverage determinations are made through LCDs. Coverage policies include a defined list of services the insurer will cover and specific exclusions. Medicare provides coverage of services that are determined to be “reasonable and necessary” for Medicare beneficiaries. If a specific item or service is not covered under an LCD, this does not mean it isn’t covered. Claims may be adjudicated on a case-by-case basis.