A 22-year-old woman is referred for further evaluation of a fractured left femur, sustained after she slipped and fell on a flat floor yesterday. X-rays showed a transverse subtrochanteric fracture, with markedly dense cortical boundaries and a reduced intramedullary diameter. Her medical and surgical histories are unremarkable, and she is not on any medications. Her mother experienced a foot fracture and a Colles fracture at the ages of 32 and 55 years respectively. These were treated individually, without further evaluation. She is a student at the local community college, has never smoked, and only drinks socially. 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). Her ESR, CRP, and renal and liver profiles (including serum alkaline phosphatase levels) are all within normal parameters.
Serum thyroid stimulating hormone (TSH) and parathyroid hormone (PTH) levels are within normal parameters.
Skull: thickening of the inner and outer cortical tables, with increased radiodensity at the skull base. Spine: increased radiodensity of all vertebrae, with sclerotic bands over the endplates (i.e. "sandwiched vertebrae" appearance). Pelvis: expanding osteosclerosis of the pelvic bones, with a "bone within a bone" appearance.
Serum tartrate-resistant acid phosphate (TRAP): 50 U/L (3.5–9.1)
You realize that transiliac bone biopsy is not indicated here.