A 22-year-old woman is referred for further evaluation of a fractured left femur. The fracture occurred yesterday, after she slipped and fell on a flat floor. X-rays revealed a transverse subtrochanteric fracture, with markedly dense cortical boundaries and a reduced intramedullary diameter.

Her medical and surgical histories are unremarkable. She is not on any medications. She does not smoke and only drinks socially. Her mother experienced a Colles fracture at 32 years of age and a fracture of the first metatarsal bone of her right foot at 44 years of age. Her family history is otherwise unremarkable.

A complete blood count is significant for a Hb of 10.5 g/dL (normal: 12-18), with normal MCV, MCH, and MCHC values. Peripheral smears confirm normochromic normocytic anemia. A reticulocyte count is 0.5% (normal: 0.5-1.5). ESR, CRP, blood urea, serum creatinine, ALT, AST, alkaline phosphatase (ALP), INR, and serum bilirubin are all within normal parameters.