Normal cortisol levels in a 24-hour urine sample typically range from 10 to 100 micrograms. However, these values can vary depending on the laboratory and the patient's specific circumstances. Elevated cortisol levels may suggest the presence of conditions such as Cushing's syndrome, which can be caused by ACTH-secreting tumors. Conversely, low cortisol levels might indicate adrenal insufficiency, which can also be associated with certain cancers.