After a turbulent week of missed phone calls, media goading, pundit speculation and sniggering jokes on the late-night TV circuit, President Clinton finally reached by telephone yesterday the man identified in The Washington Post as his long-lost half brother.

They talked about dieting.

"He says he has stress tests taken every year, jogs and keeps his weight down," Henry Leon Ritzenthaler told CBS Radio after the call. Ritzenthaler, 55, suffers from a heart condition and was interested in learning about the family medical history.

Clinton phoned his putative big brother at his home in Paradise Valley, Calif. They chatted for about 15 minutes.

"They had a warm conversation and agreed to get together at some point in the future," said White House spokeswoman Dee Dee Myers.

Late Friday, Ritzenthaler placed a call to The Post and left this message: "The president was a very nice person, pleasant to talk to, and I was very pleased to hear his voice."

Last Sunday, on Father's Day, Ritzenthaler surfaced as Clinton's half brother in a Post profile of W.J. Blythe, the president's father. The article said that 10 years before marrying Clinton's mother, Blythe had married Adele Gash, a saloon keeper's daughter from Sherman, Tex., and that the union had produced a baby boy. Birth records identified the baby as Henry Leon Blythe, who became Henry Ritzenthaler years later.

Ritzenthaler says he wrote to Clinton during the presidential campaign, but his letter was never answered.

Earlier this week, Clinton had tried calling Ritzenthaler, but he said nobody was at home. Ritzenthaler was in New York, being interviewed for network TV. They finally connected at 1:30 yesterday.

The president did not acknowledge that Ritzenthaler is his half brother. Asked by CBS if he thought Clinton believed they were brothers, Ritzenthaler said, "I think he does."

Blythe married Clinton's mother in 1943. He died in a car accident a few months before Clinton was born in 1946.

Ritzenthaler's mother, Adele Gash Coffelt of Apple Valley, Calif., told The Post she married Blythe in Texas in 1935, when they were both 17, and conceived Henry Leon with him in 1937, after their divorce.

Blythe later married Virginia Cassidy, Clinton's mother. Cassidy, now Virginia Kelley, told The Post that she never knew her husband had been previously married or had fathered another son.

The Post article said public records, including marriage and birth certificates, back up Coffelt's version of events.

H L Ritzenthaler