Thyroid No Surgery 101: Osteoporosis OP, Another complication of thyroid surgery?
- Patients who underwent thyroidectomy had a 1.43 times higher risk for OP than patients who did not undergo thyroidectomy, irrespective of the extent of thyroid surgery.
- Do you see why having thyroid surgery without serious pre-surgery evaluation by outside consultant to see it is necessary.
- Besides the usual serious surgical complications now we add osteoporosis.
- The study should give pause to consider other long-term implications of thyroid surgery.
- Many only think short term results of getting the suspicious nodule removed and fail to spend time looking at the long term effects of the removal of your thyroid gland.
- Call me for a consultation at 310-393-8860 or email to firstname.lastname@example.org.
Thyroidectomy Increases the Risk for Osteoporosis
Following thyroidectomy, patients may require thyroid hormone supplementation (partial thyroidectomy) or replacement (total thyroidectomy), and in patients with thyroid cancer, higher doses of levothyroxine may be prescribed to achieve thyroid-stimulating hormone (TSH) suppression. There are conflicting studies on the effects of levothyroxine on bone density and the risk of osteoporotic fractures. The purpose of this trial was to study the effect of thyroxine treatment on the risk of osteoporosis (OP) and osteoporotic fractures (OF) in thyroidectomy patients and to compare the risk of osteoporosis and osteoporotic fractures between thyroidectomy patients and a control group using a population-based database (1).
The National Health Insurance (NHI) program in Taiwan offers universal health insurance for all residents of that country; the NHI Research Database contains clinical information on all patients, and deidentified data from this database were used in this study. The thyroidectomy cohort included patients who were >20 years and who had undergone thyroidectomy between January 2000 and December 2005; these patients were divided into partial thyroidectomy and combined subtotal/total thyroidectomy groups. The control cohort was propensity-score matched in a ratio of 1:4 for patients as compared with controls for age, sex, urbanization, and comorbidities (diabetes mellitus, hyperlipidemia, hypertension, coronary artery disease, congestive heart failure, obesity, chronic kidney disease, chronic obstructive pulmonary disease, and malignancy excluding thyroid cancer). Patients with a history of osteoporosis or thyroid disease (ICD-9 codes 242-246; primarily hyperthyroidism) were excluded from the analysis.
The primary outcome of this study was the new diagnosis of OP and OF during the postoperative follow-up, defined as at least two instances of outpatient records or one inpatient record. Patients were followed until December 31, 2013 or until the date that any of the following occurred: diagnosis of OP or OF, withdrawal from the NHI program, death.
The study included 1426 thyroidectomy patients (including 474 [33.2%], who underwent partial thyroidectomy) and 5704 control patients. OP or OF developed during follow-up in 120 thyroidectomy and 368 partial thyroidectomy patients , with an incidence of 8.33 per 1000 person-years in the thyroidectomy cohort and 6.39 per 1000 person-years in the control cohort. After adjustment for age, sex, urbanization level, and comorbidities, the adjusted hazard ratio (aHR) was 1.40 (95% confidence interval [CI], 1.14–1.72; P<0.05). The risk of OP and OF was higher both in patients underwent partial thyroidectomy (aHR, 1.52; 95% CI, 1.11–2.08) and those who underwent subtotal/total thyroidectomy (aHR, 1.34; 95% CI, 1.05–1.72 ). Thyroidectomy also increased the risk of OP in both groups, with an aHR of 1.55 (95% CI, 1.13–2.14) for partial thyroidectomy and 1.37 (95% CI, 1.05–1.72) for subtotal/total thyroidectomy. When the risks of OP or OF were analyzed separately, the risk of OP (but not OF) was higher for patients who underwent thyroidectomy, in both the partial thyroidectomy (aHR, 1.55; 95% CI, 1.13–2.14) and the subtotal/total thyroidectomy (aHR, 1.36; 95% CI, 1.05–1.72) groups.
The cohort was then stratified by age, sex, and comorbidities. A higher risk of OP or OF was present in younger (20-49 years) thyroidectomy patients than in the control cohort (aHR, 1.55; 95% CI, 1.12–2.15), although there was no difference in patients 50 years and older. The risk of OP or OF also was higher in women who underwent thyroidectomy (aHR, 1.41; 95% CI, 1.14–1.75) than in men who underwent thyroidectomy. When thyroidectomy patients were classified on the basis of the extent of surgery and total duration on thyroxine, there was no difference in the risk of OP or OF in the partial or total thyroidectomy patients, as compared with the control group if the duration of exposure was less than 1 year. However, the risk of OP or OF increased in both the partial thyroidectomy (aHR, 2.47; 95% CI, 1.42–2.31) and subtotal/total thyroidectomy (aHR, 1.84; 95% CI, 1.22–2.76) groups if postoperative levothyroxine was used for more than 1 year.
In this population-based study, patients who underwent thyroidectomy had a 1.43 times higher risk for OP than patients who did not undergo thyroidectomy, irrespective of the extent of thyroid surgery. The impact of thyroidectomy on the incidence of OP or OF was higher after longer periods of treatment with thyroid hormone postoperatively. There was no increased risk of OF after thyroidectomy. The authors recommend regular surveillance of bone density in patients following thyroidectomy, especially younger patients.
In this study, the authors used a large, nationwide, population-based database to examine the effects of thyroxine on the development of osteoporosis and/or osteoporotic fractures in patients who had undergone partial thyroidectomy or subtotal/total thyroidectomy and in control patients who have not undergone thyroidectomy and with no history of thyroid disease (1). These findings corroborate those of other recent studies, which examined the effect of thyroid hormone levels on bone mineral density, both physiologically and in the setting of thyroid hormone suppression therapy for patients with thyroid cancer (2–4).
This study is particular in that it examines the effects of the extent of thyroidectomy (partial vs. total) and duration of thyroid hormone therapy in patients who have undergone thyroid surgery for both benign and malignant disease. In the current ongoing debate regarding the optimal treatment of patients with indeterminate thyroid nodules and low-risk differentiated thyroid cancers, potential effects of long-term thyroid hormone supplementation, even in patients who have undergone partial thyroidectomy, should also be considered. In a recent study of patients who underwent thyroid lobectomy, 478 of 555 did not take thyroid hormones prior to surgery. In postoperative follow-up, 350 (73%) had a TSH >2 mIU/L (the threshold recommended by the current American Thyroid Association guidelines for patients with low-risk thyroid cancers undergoing thyroid lobectomy) and might require thyroid hormone supplementation postoperatively.(5) This is particularly interesting, because in this study patients who underwent partial thyroidectomy had a higher adjusted hazard ratio for the development of osteoporosis or osteoporotic fractures, as compared to the adjusted hazard ratio for those who underwent total thyroidectomy.
There are several limitations to this study. First, the study does not include biochemical data; therefore, while the study traced associations between the extent of thyroidectomy and use of thyroid hormone postoperatively, it remains unclear what threshold levels of TSH and/or free T4 may lead to an increased risk of osteoporosis or osteoporotic fractures. In addition, preoperative data regarding bone mineral density is absent. Lastly, the study does not examine patients with benign thyroid disease and thyroid cancer separately; therefore, it is difficult to determine what may be related to the effects of any exogenous thyroid hormone usage versus intentional thyroid hormone suppression therapy. In addition, the follow-up in some patients may have been relatively short and the true long-term effects of thyroid hormone supplementation and/or replacement may not be fully identified.
Despite these limitations, the study should give pause to consider other long-term implications of thyroid surgery and the potential need for postoperative thyroid hormone therapy. Additional studies in patients who have undergone thyroidectomy for benign disease may be difficult to assess, given the long-term follow-up required, but should be considered as the number of detected thyroid nodules and number of thyroidectomies continue to increase, both in the United States and worldwide.