Accelerated bone loss in hypothyroid patients overtreated with L-thyroxine

Area of Science:

• Endocrinology
• Bone Metabolism
• Gerontology

Background:

• Thyroid hormone replacement therapy is common for hypothyroidism.
• Overtreatment can lead to suppressed thyroid stimulating hormone (TSH) levels.
• The impact of suppressed TSH on bone mineral density is not fully understood.

Purpose of the Study:

• To compare bone mineral loss rates in women with suppressed TSH due to thyroxine treatment versus women without thyroid disease.

Main Methods:

• Prospective study of women in a calcium supplement trial.
• Bone mineral density measured by photon absorptiometry over approximately 2 years.
• Comparison of bone loss rates between thyroxine-treated women with low TSH and controls.

Main Results:

• Women with low TSH levels exhibited significantly greater bone loss from the spine compared to controls.
• Trends of increased bone loss were observed at the radius and femoral neck, though not statistically significant.
• No significant differences in biochemical markers of bone metabolism were found between groups.

Conclusions:

• Suppressed TSH levels in thyroxine-treated women are associated with increased spinal bone loss.
• These findings suggest an elevated risk of osteoporosis in this patient group.
• The lack of biochemical changes may be due to the mild degree of TSH suppression.