Olympic double gold medalist Greg Louganis overcame the challenge of Mike Wantuck and successfully defended his national platform diving championship yesterday in the U.S. Diving Indoor Championships at Indianapolis, then presented the gold medal he earned to AIDS victim Ryan White.

"I heard about Ryan as I traveled around the country," said Louganis, who over a four-day span swept all three men's national titles for the fourth straight time to bring his record total of national championships to 38. "My injuries are superficial and they'll heal. I wish that that were the case with Ryan."

White, 14, from Kokomo, Ind., is a hemophiliac and contacted Acquired Immune Deficiency Syndrome during a blood treatment. His illness was diagnosed in December 1984. Authorities kept him from attending school for all but one day this year until he won a court order April 10.

"I had a little bit of motivation," said Louganis, who invited White to yesterday's competition and said he decided for that reason to compete despite the fact that "every time I hit the water it was excrucriating pain" because of some warts he had removed on Wednesday.

In the women's platform finals, Michele Mitchell and Wendy Wyland placed one-two. Mitchell, who won the three-meter Saturday night, claimed her seventh national title.