full free access: Levothyroxine dose & risk of fractures in older adults: nested case-control study -- Women's College Hospital Toronto study (hypothyroidism)

Note:
the study excluded thyroid cancer survivors but a quick scan does not indicate a search of the database/inclusion/exclusion of a prior/present history of other cancers with the exception of reference #44 prostate cancer

(eg. pre-menopausal longterm cancer survivours/longterm use of hypothydroism medications - comments/opinions welcome on this issue)

Also known as:  

Brand names
Eltroxin
Estre
Euthyrox
Levo-T
Levotabs
Levothroid
Levoxyl
Novothyrox
Synthroid
Thyrox
Unithroid  

Brand names of combination products
Thyrolar 1 (containing Thyroxine and Triiodothyronine) Thyrolar 1/2 (containing Thyroxine and Triiodothyronine) Thyrolar 1/4 (containing Thyroxine and Triiodothyronine) Thyrolar 2 (containing Thyroxine and Triiodothyronine) Thyrolar 3 (containing Thyroxine and Triiodothyronine)
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Study cohort

The cohort consisted of Ontario residents aged between 70 and 105 years with at least one prescription for levothyroxine between 1 April 2002 and 31 March 2007. People entered the cohort on the date of their first prescription. Although the Ontario drug benefit database records prescription data for patients starting at age 65 years, we excluded those under 70 to provide at least five years of drug history for all participants.

We excluded people if they had received dialysis or palliative care in the six months before entry to the cohort because of differing goals of care or bone physiology. People were also excluded if they had a history of thyroid cancer or previous hyperthyroidism before entry to the cohort, which might prompt higher dose targets for levothyroxine beyond mere replacement.......