Endocrine Abstracts

Introduction: It has been seen that Zoledronic acid (ZA) infusion induces an acute inflammatory response associated with rise in inflammatory markers and changes in thyroid function tests resembling non thyroidal illness syndrome. It is also postulated that amino group of ZA has a role in causation of these thyroid function abnormality. (1)

Material and methods: An observational study at tertiary care hospital of India where thyroid functions tests were studied at day 0,1,2,3,7 and day 42 post ZA infusion. Anti TPO Antibodies were also done at baseline. Subjects with pre-existing thyroid disorders, on therapies which can alter thyroid functions, critically ill patients, secondary osteoporosis patients, who received ZA in past and patients with BMI > 30 Kg/m² were excluded from study.

Results: Total of 168 patients participated in the study. 159 (94.6%) were post-menopausal females and 9 (5.35%) patients were males. In our study it was observed that there was transient fall in free T3 at day 1 and day 2 and it normalized by day 7 (P value <0.05). Changes in FT4 post ZA infusion were not statistically significant. TSH rose after ZA infusion in our study and this rise continued till final follow up till day 42 post ZA infusion. Rise in TSH post ZA infusion was higher in patient having positive anti TPO antibodies. (P value <0.05).

Conclusion: Study found that Free T3 hormone falls significantly after 5 mg ZA infusion at day 1 and day 2. The present study also found that TSH hormone rises significantly after ZA infusion when followed till day 42. Rise in TSH was significantly higher in subjects having evidence of thyroid autoimmunity.

Reference

1. Karga H, Giagourta I, Papaioannou G, et al Transient changes in thyroid functions tests after zoledronic acid infusion. Endocr J. 2011;58(11):969-77. doi: 10.1507/endocrj.ej11-0039. Epub 2011 Sep 3. PMID: 21891972.