CPT code 94725, referred to as the membrane diffusing capacity, can be used to report the measurement of the components of DLCO, the DMCO, and θVc.23 No clinical value has been established for this test. However, Medicare claims for 94725 have risen from 7,941 tests in 2000 to 87,496 tests in 2005,28 an enormous increase of > 1,000% over that 5-year interval. The places of service for these tests were in physicians' offices (97.18%), in the home (2.63%), in custodial care (0.16%), and in nursing homes (0.04%).28 The majority of tests were reported from independent diagnostic testing centers (59.47%). General practitioners (13.24%) and family practitioners (9.66%) made up most of the rest of the reporting practices. Only 4.56% of the tests were reported from pulmonologists. It is difficult to justify the measurement of the membrane diffusing capacity in the PF laboratory, let alone in the home, under custodial care, or in a nursing home.