Bone Mineral Density in Premenopausal Women Receiving Long-term Physiological Doses of Levothyroxine

Abstract

Total body and regional bone mineral density (BMD) levels were determined in 26 premenopausal women with Hashimoto's thyroiditis receiving long-term physiological doses of levothyroxine sodium replacement therapy. The BMD levels of each patient were compared with the mean of the BMD levels of age-matched normal controls. The mean levothyroxine sodium dose was 111 +/- 6 micrograms/d, and the mean duration of treatment was 7.5 +/- 5.3 years (range, 1 to 24 years). Dietary calcium intake was similar in both groups, as were serum thyroxine, triiodothyronine, free thyroxine index, and thyrotropin levels. Women receiving the levothyroxine treatment had normal total body BMD levels but had significantly lower BMD levels at the femoral neck (-5.7%), femoral trochanter (-7.0%), Ward's triangle (-10.6%), both arms (right, -7.8%; left, -8.9%), and pelvis (-4.9%). In contrast, lumbar spine BMD levels were similar in the two groups. There was no correlation between the total body or different regional BMD levels and the duration or dosage of levothyroxine treatment or thyroid function test results. However, the z score of the femoral neck of these patients showed a significant negative correlation with their serum free thyroxine index levels. We conclude that patients receiving physiological doses of levothyroxine may have decreased bone density. Thyroid functions in patients receiving long-term levothyroxine treatment should be closely monitored and bone densitometry should be performed in patients at risk for osteoporosis.

Bone mineral density in adolescent females treated withl-thyroxine: a longitudinal study

“…Thus, our data did not confirm those of Kung and Pun [15] who found significantly lower BMD in regional skeleton in premenopausal women treated with replacement doses of L-T4 and no other risk factors for bone loss.…”

“…In recent years, several reports recognised that chronic L-thyroxine (L-T4) therapy may be associated with reduced bone mass [10,20]. Some degree of L-T4 over-treatment leading to mild hyperthyroidism may be the cause of the decreased bone mass [8][9][10], but decreased bone density has also been found in premenopausal women with Hashimoto thyroiditis who received physiological doses of L-T4 [15].…”

Increased fracture frequency in adult patients with hypopituitarism and GH deficiency

“…No continuous overdosage of these medications was noted clinically or according to laboratory evaluations at the follow-up, but a previous minor overdosage of these two hormone substitutions cannot be excluded. This might have aggravated the bone loss (12,13).…”

The effect of long-term, non-suppressive levothyroxine treatment on quantitative ultrasonometry of bone in women

“…However, other studies have failed to confirm this decremental effect of L-T 4 treatment on BMD (14)(15)(16)(17) or on the prevalence of fracture (18,19). L-T 4 treatment that does not suppress TSH seems to have little effect on bone (20)(21)(22)(23). A recent, large prospective study on elderly ambulatory women found no consistent evidence that a low TSH concentration was associated with a low BMD or accelerated bone loss (2).…”