Apple Chief Executive Steve Jobs sought to soothe investor concerns about his health on Monday, saying his weight loss was caused by a hormone imbalance that is relatively simple to treat.
Shares of Apple rose more than 5 percent in midday trade, as Jobs, a pancreatic cancer survivor, said he would remain CEO during his recovery and that his doctors expect him to regain his weight by late spring.
"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," Jobs said in a statement, breaking his silence about his health for the first time in months.
The statement followed widespread investor concern about the executive's health, after Jobs decided not to give the keynote speech at Apple product showcase Macworld this week. Speculation about his health resurfaced in June 2008, when Jobs appeared markedly thinner at an Apple event.
Jobs is seen as the driver of Apple's successful products, including Macintosh computers, iPod media players and iPhones.
He acknowledged he had been losing weight throughout 2008 and that his doctors determined "a hormone imbalance that has been 'robbing' me of the proteins my body needs to be healthy."
He said the remedy for "this nutritional problem is relatively simple and straightforward" and that he has begun treatment.
Investors who had been unnerved by Jobs's gaunt appearance last year, and the lack of a clear explanation from the company, heaved a sigh of relief.
Pacific Crest Securities analyst Andy Hargreaves said the announcement did allay his and many investors' concerns about Jobs' health, but said he doesn't expect the whispers to stop.
"Is it going to put the fears to rest? No ... just based on experience I would expect there to continue to be rumors on his health deteriorating. But this is pretty definitive," he said.
Apple's board said in a separate statement that Jobs has its full support during his recuperation.
Jobs said the cause of his weight loss had been a mystery to himself and his doctors until he decided a few weeks ago that getting to the root of the problem was his top priority.
Dr. Stuart Weiss, an endocrinologist at New York University Langone Medical Center said the announcement left some questions unanswered.
"With the information he's given, it's very difficult to give a precise diagnosis," he said.
Weiss said some patients who have undergone surgery to remove pancreatic cancer are unable to properly absorb nutrients and suffer weight loss if the pancreas is "insufficient" -- meaning it no longer produces vital digestive enzymes.
He said pancreatic insufficiency is fairly easy to diagnose and drugs can improve the situation within weeks or months.
Another possibility, he said, is that traces of pancreatic cancer could escape into the bloodstream after surgery and produce hormones that interfere with absorption of food.
But in that scenario, Weiss said patients can require more cancer surgery and must be given injections of drugs that limit the hormone-secreting ability of lingering tumor cells.
Shares of Apple rose 5 percent to $95.40 in afternoon trade on the Nasdaq. But the stock remains far below its 12-month high of $192.24, hit in May 2008, amid concerns about how the slump in consumer spending will hurt sales of the company's high-end products.
In addition, some analysts fear that without a big product launch - such as last year's 3G iPhone, there will be no share catalyst in what is expected to be a dismal year for computer and consumer electronics companies.
However, fears about Jobs' health seemed to be top of mind for many investors, so Monday's announcement may succeed in bolstering Apple's shares in the near term.
Adam Harter, an analyst at Financial Enhancement Group, said his company added to its position in Apple a couple of months ago, when the stock was trading in the mid-$80s.
"At that point of time we felt the Steve Jobs' premium was already backed out of the stock price. So anything that says he's not in bad health is good news and this appears to say he's in much better health than the market had anticipated so the upside can be significant," Harter said.