Silva, 37, was pulled last week from a light heavyweight bout against Chael Sonnen at UFC 175 when it became clear the Nevada State Athletic Commission would not grant him a fighter's license after he fled from a random drug test.
The veteran martial artist appeared before the NSAC at an "information gathering" Tuesday. Las Vegas-based attorney Ross Goodman represented Silva.
Goodman admitted on his client's behalf that Silva had been taking diuretics at the time of the test. Diuretics, which can be used to quickly cut weight or mask performance-enhancing drug use, are banned in combat sports.
Silva said he was using diuretics in conjunction with anti-inflammatories to deal with a wrist injury he had suffered in February.
"In February of this year, he injured his wrist," Goodman said. "He was scheduled to fight [in May]. In early May, X-rays confirmed he had fractured his right wrist. The UFC moved the fight to July 5.
"Mr. Silva, regretfully, at that time, started taking diuretics. He was taking diuretics for the sole purpose of minimizing the inflammation and [decreasing] water retention."
Prior to Silva's admission, the independent sample collector who attempted to test him May 24 provided a detailed account of what occurred leading up to the refused test.
Jim Guernsey, who said he has 34 years of experience collecting drug-testing samples, said he attempted to reach Silva at his residence in Las Vegas at approximately 1 p.m.
After receiving no answer at Silva's residence, he attempted to call both the fighter and his wife, unsuccessfully. Guernsey said he later found out the numbers provided to him for both were incorrect by one number.
Shortly after, Guernsey drove to Silva's Las Vegas gym, where he said he found him and other members of the gym. He informed Silva the NSAC had requested a random drug test, which he was to administer.
"He asked me if he could talk to his manager," Guernsey said. "I asked him if this person was at the gym, and he said yes. He went into an office in the middle of the gym and came out after only a few seconds.
"He walked back to the front counter and then past the office and towards the back of the gym and around to the right. I casually followed behind him, and when I turned around the corner, I realized there was an exit and bathroom."
Guernsey, who took notes during the incident, said he searched the bathroom and, upon not finding Silva, "came to the conclusion he left."
Silva admitted to the details as described by Guernsey.
"He was surprised," Goodman said. "This was the first time in his career where something like this, somebody showing up at his gym. That does not negate or minimalize what Mr. Silva did. He's here to apologize to the commission.
"He was concerned the diuretics would show up on his sample. There should [not] be inference or suggestion Mr. Silva was trying to mask or hide any [performance-enhancing drugs] or [testosterone use]."
The NSAC did not discuss disciplinary action Tuesday but will do so at a future hearing. Silva, who was not licensed at the time of the random test, could be made ineligible to apply for a license for a certain period of time.
Silva (35-12-1) is a former Pride middleweight champion. He made his professional MMA debut in 1996. Prior to this incident, he had never failed a drug test.