Nicole Kidman has reportedly had a test for the bone disease osteoporosis.
Sources in Los Angeles said the Oscar-winner was given a bone density test to check for signs of the condition.
Osteoporosis, so-called brittle bone disease, leaves people prone to breakages.
Nicole - who broke two ribs while filming Moulin Rouge - is said to be suffering from too much work and a lack of proper food.
The disease, which can prove fatal, can be caused by excessive weight loss.
The Daily Mail said the 37-year-old, who is 5ft 10in, is the thinnest she has ever been, weighing in at eight stone.
Kidman is aware of her weight problem, having once said: "I would love to have boobs and a butt like Jennifer Lopez, I honestly would.
"But I can't have them, and I'm not going to have surgery, so there it is guys."
Sky News