By Dylan Howard - Senior Executive Editor, Star magazine

Whitney Houston failed a routine medical check two weeks before she was found dead in a hotel bathtub, Breaking Celebrity News has exclusively learned.

The legendary pop singer had sought a facelift to be performed by a Beverly Hills, Calif., plastic surgeon.

But Dr. Marc Mani, a board certified plastic surgeon, refused to perform the procedure on Houston after she didn't pass the medical clearance exam that tests a patient's heart, lung and liver, according to a source.

"She was concerned about her appearance and wanted a facelift," the source said.

Dr. Mani refused to confirm to Breaking Celebrity News whether Houston, 48, who was found dead in the bathtub of her suite at the Beverly Hilton on Feb. 11, had attended his clinic, citing federal medical privacy laws.

Speculation has grown over Houston's cause of death, which has not been determined pending the outcome of toxicology tests that could take up to six weeks.

However, as Breaking Celebrity News was first to report, preliminary results have revealed sedatives were found in Houston's system.

The tests showed the I Will Always Love You hitmaker had ingested sedatives, particularly benzodiazepines, before she was found in the fourth-floor suite of the hotel.

Detectives were said to have found prescription pill bottles of Xanax, lorazepam, and valium - which are all benzodiazepines - as well as Ibuprofen, Midol and Amoxicillin.

As Breaking Celebrity News also reported, Houston visited a doctor three times in a period of eight days before her death: on Feb. 2, Feb. 7 and Feb. 10.

Despite refusing to specifically comment on Houston, Dr. Mani spoke out about his profession, which has come under fire since it emerged doctors had prescribed pills to Houston.

Dr. Mani said he would not “overindu