The authors stated that 21 studies were included, and that these included 6 prospective studies and 17 cross-sectional studies with and without control groups. The data extraction tables list 6 reference numbers for longitudinal studies and 18 unique reference numbers for cross-sectional studies; however, 2 studies are listed as both longitudinal and cross-sectional. There appeared to be no obvious explanation for these discrepancies.
The sample size ranged from 5 to 52.
Twelve cross-sectional studies (n=304) and 4 prospective studies (n=67) evaluated effects in premenopausal women. Fourteen cross-sectional studies (n=326) and 4 prospective studies (n=132) evaluated effects in postmenopausal women. Eight cross-sectional studies (n=147) and 1 prospective study (n=9) evaluated effects in men.
All studies.
Four of 6 prospective studies reported that TSH-suppressive thyroxine therapy was associated with a significant decrease in BMD from baseline. Four of 17 cross-sectional studies reported a significant difference between patients with DTC and controls.
Premenopausal women (16 studies).
Two of the 12 cross-sectional studies reported a significant decrease in BMD in patients with DTC compared with controls. The other 10 cross-sectional studies reported no significant differences between patients with DTC and controls. Two of the 4 prospective studies reported a significant decrease in BMD in patients with DTC compared with controls.
Postmenopausal women (16 studies).
Four of the 14 cross-sectional studies reported a significant decrease in BMD in patients with DTC compared with controls. The other 10 cross-sectional studies reported no significant differences between patients with DTC and controls. Two of the 4 prospective studies reported a significant decrease in BMD in patients with DTC compared with controls; in one of these studies (a randomised controlled trial) the BMD was unchanged in patients randomised to calcitonin or calcium, but was significantly lower in patients taking placebo.
Men (9 studies).
One of the 8 cross-sectional studies reported that BMD was significantly lower in patients with DTC or Graves disease compared with controls. The only prospective study reported a significant decrease in BMD compared with baseline at the distal radius, but not the femoral neck, in patients with DTC.