Case report: fast reversal of severe osteoporosis after correction of excessive levothyroxine treatment and long-term follow-up.

This case report describes a 38-year-old woman, who presented with bilateral femoral stress fractures and osteoporosis after years of excessive levothyroxine treatment. Her bone health was restored rapidly and long-lasting with the reduction of levothyroxine dosage. No bone-active treatment was warranted.

INTRODUCTION: Hyperthyroidism is a known risk factor for osteoporosis and fractures. Recent studies on patients with serum thyrotropin-suppressive therapy have not, however, indicated adverse effects on bone during long-term follow-up.

METHODS: This case report describes long-term follow-up data of a clinically euthyreoid patient, who developed symptomatic osteoporosis due to excessive levothyroxine treatment.

RESULTS: After correction of levothyroxine dosage, her bone mineral density (BMD) and previously elevated serum osteocalcin levels normalized rapidly and she remained free from fractures during 23 years of follow-up over menopause.

CONCLUSION: Excessive TSH suppression contributed to the secondary osteoporosis in this patient; BMD normalized after dose reduction of levothyroxine and no fractures occurred during 23 years' follow-up. Some patients develop severe osteoporosis if they are over-substituted with levothyroxine, and decent follow-up of patients with levothyroxine supplementation is mandatory.