maloc, high doses of synthroid can suppress levels of parathyroid hormone confounding a hyperparathyroid diagnosis.
On the other hand the distal third is the area most susceptible to misreading on dexa. The forearm is a small bone area because of this if a patient moves at all even a tremor or supressed cough during the scan, blurring leads to an underestimation of BMD.
Positioning is tricky. Your arm has to be positioned perfectly flat to avoid rotational artifacts and to recognize anatomical reference points ( radial endplate, the ulnar styloid), BMD varies vastly from the wrist to the elbow.
Finally if you have a small arm, because dexa doesn't account for volume a small arm will register a lower bmd.
I really like that your doctor measured your forearm. Forearm measurements are usually reserved for those who can't be measured elsewhere. But they are wonderful for catching a damaged parathyroid gland.
I'd be reluctant to take Reclast with mild osteopenia, partly because of the possibility of side effects, but more because of its mechanism of action. It slows down bone turnover first by blocking the cells that carry away damaged bone that slow down the cells that rebuild bone. Was your forearm -4.1 on both dexas.