After doctors removed her thyroid gland due to an initial cancer diagnosis, test results revealed Argentina's president Cristina Fernandez de Kirchner didn't actually have cancer.

Fernandez underwent surgery on Jan. 4, just weeks after she took office, according to The Associated Press.

Her spokesman, Alfredo Scoccimarro, said she doesn't need to take any radioactive iodine, something commonly prescribed after thyroidectomy to kill any residual cancer cells.  She will, however, have to be on thyroid hormone replacement therapy for the rest of her life.  Iodine is used in patients with papillary thyroid cancer and follicular thyroid cancer, according to the American Cancer Society.

Endocrinologists not involved in the president's treatment told ABCNews.com her situation is more the exception than the rule.

"These are called false positive cases, and they do happen, but they are the minority of cases," said Dr. Antonio C. Bianco, professor and chief of the division of endocrinology, diabetes and metabolism at the University of Miami School of Medicine.

What generally happens, he said, is during a routine physical examination, a doctor or other healthcare provider will examine a person's neck and check for lumps, also known as nodules.

"If there is a nodules, the person will then go for an ultrasound to determine how big it is," Bianco said.  "If it's more than 1.5 cm. long, then it will be biopsied."

The biopsy involves inserting a small needle and removing cells from the lump.  A pathologist will then examine the cells and determine whether there is cancer present.

"The pathologist will then determine the risk that those cells are malignant," said Dr. Glenn Braunstein, director of the Thyroid Cancer Center at Cedars-Sinai Medical Center in Los Angeles.  If there's about a 20 percent to 30 percent chance those cells are cancerous, many doctors - including Braunstein - recommend removing the thyroid gland.

Depending on the type of thyroid cancer, radioactive iodine may also be necessary.  Once the gland is removed and iodine treatment is complete, the cancer typically is gone.

But removing the entire thyroid requires a person to be on thyroid replacement hormones for life, since those hormones are essential for maintaining the body's metabolism.

"If you take the hormone tablet, most people will live just fine - about 85 percent of people do well," Bianco said.

While Braunstein said about 95 percent of nodules are benign, people at high risk for thyroid cancer - men younger than 40, people who have had a lot of radiological testing to the head and neck area, those with large lymph nodes in the neck or those with a family history of thyroid cancer - should have biopsies.

But biopsies, he said, are over-used across the country,  in part because thyroid cancer is on the rise, but also because there is a lack of better diagnostic tools.

"The problem is what to do about thyroid cancer once you know it's there," Braunstein said. "Many people had surgery but their cancer wouldn't have done any harm if it were just left in the neck.  We just don't know how to tell them apart, so the biopsies are necessary."