Apple's Steve Jobs will stay as CEO

Still, the announcement is unlikely to end speculation about Jobs, said Brian Marshall, an AmTech Research analyst. He expects Jobs to step down as CEO this year, most likely remaining an adviser to the company. Marshall said he believes Jobs’ departure would cut $10 to $15 from Apple’s stock price.

An Apple spokesman declined to comment, and Jobs said in his letter that “I will be the first one to step up and tell our board of directors if I can no longer continue to fulfill my duties as Apple’s CEO.”

Stephen M. Davis, a senior fellow at the Millstein Center for Corporate Governance and Performance at Yale University, said the announcement fits Apple’s pattern of “releasing information to shareholders in dribs and drabs.”

“It’s not a technique designed to win loyalty from investors over the long term,” he added. “This is a public company in which millions of investors have entrusted their savings and in which millions of customers also have a stake.”

Medical experts not involved in Jobs’ treatment said there wasn’t enough information in his statement to know exactly what was behind his weight loss.

While a hormone imbalance might be unrelated to his cancer, pancreatic dysfunction would be the top suspicion, said Dr. Richard Auchus, an endocrinologist at UT-Southwestern Medical Center in Dallas.

“The pancreas makes digestive enzymes, and if the pancreas doesn’t make enough of those, then people can’t digest foods and getting nutrients is a problem,” Auchus said. The solution could be as simple as taking pills to replace or augment the enzyme, as is commonly done to treat pancreatic insufficiency in children with cystic fibrosis, Auchus said.

Dr. F. Taylor Wootton, a gastroenterologist and spokesman for the American Gastroenterological Association, said another possible explanation for the weight loss is an overactive thyroid gland. Symptoms include weight loss and fatigue. An overactive thyroid is treated with medication, radioactive iodine or surgery.

Apple’s board released a separate statement, saying, “Apple is very lucky to have Steve as its leader and CEO, and he deserves our complete and unwavering support during his recuperation. He most certainly has that from Apple and its board.”

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