A T score of minus one or higher and Z score of zero or higher is considered a normal result from a bone density scan for a woman, according to WebMD. The test is most accurate for women of average stature, between 5 feet and 5 feet 10 inches tall.
The T score represents the comparison of the subject's bone mass to that of a healthy 30-year-old. A T score result of minus one to minus 2 1/2 indicates osteopenia, while lower than minus 2 1/2 indicates osteoporosis, reports WebMD. The Z score is a comparison to others of the same age and gender. Negative Z scores require further evaluation to determine the cause of the reduction in bone mass.