What does a "low normal" bone density test mean?

Very little!: When the world health organization arbitrarily set a level of bone mineral density (bmd) below which a person was said "to have" osteoporosis, the opportunity was immediately seized by interested parties to declare a range better than that density but adjacent to it as "osteopenia". Above that is called "normal" bmd is a continuum! normal is normal. Low normal means normal.

Osteopenia: Norma bone density measurements are compared to normla young bones, called the t score. A T-score of 1 is normal. The more negative the number the worse the bone density is. So a T-score of more negative then -2.5 is osteoposrosis. Osteopenia(pre osteoporosis) is therefore between 1 and -2.5 scores.