Jobs further noted in his Jan. 5 letter that the remedy for the problem is "relatively simple and straightforward," and that he has already begun treatment to correct the condition.
An e-mailed message to an Apple spokesperson for further comment was not immediately returned. Following Jobs' announcement, Apple Inc. released a statement indicating that Jobs will continue to hold the CEO post for the company.
Pancreatic cancer experts said an effective lockdown on Jobs' medical particulars since he first announced he had a pancreatic tumor in 2004 makes it difficult to determine for certain the exact nature of his condition.
"He's done a very good job of keeping this private," said Dr. Harold Frucht, associate professor of clinical medicine at Columbia University.
But he said that judging from the information available, it is unlikely that Jobs required a Whipple procedure -- an operation that removes a large portion of the pancreas and can lead to profound hormonal imbalances.
Instead, he said, he believes the surgeon who operated on Jobs probably performed what is called an enucleation -- a procedure in which a doctor in essence scoops a tumor out of the organ, leaving most of the pancreas intact.
"A lot of surgeons would have done a Whipple procedure, but for neuroendocrine tumors this is not generally necessary," Frucht said. "Good surgeons who have dealt with a lot of these tumors would conduct the surgery without taking out the pancreas."
Frucht said hormonal imbalances are not rare in patients with a neuroendocrine tumor, and these symptoms can resurface years after these tumors are removed. And he concurred that if indeed Jobs had suffered from a neuroendocrine tumor, the treatment for rebalancing his hormone levels would likely be a simple matter.
"Probably up to 60 percent of patients with a biochemical cure after surgery -- all hormone levels are normal and no tumor on imaging -- will have a recurrence of hormone excess production," he said. "Treatment would be simple -- medical treatment to treat the manifestations of excess hormone production."
However, Dr. Anne Peters, director of USC clinical diabetes programs, said it is still possible that Jobs underwent a Whipple procedure, the operation most often performed for the most common form of pancreatic cancer. And she said the downstream effects of this procedure can also lead to weight loss, as the operation normally removes the tissue responsible for producing important digestive enzymes.
"Life after a Whipple is difficult, because these hormones and enzymes need to be replaced, and often the treatments aren't quite as good as the body's own production of them," she said. "My post-Whipple patients tend to be thin, and have to work hard to maintain adequate nutrition."
She added that the treatment for this type of lingering condition are also straightforward, though they must be maintained for life.