Endocrine Abstracts

Background

Thyrotropin Stimulating Hormone Suppression Therapy (TSHST) in Differentiated Thyroid cancer (DTC) patients can result in reduced bone mineral density (BMD) which is a potential serious problem [1]. Studies on the effects of TSHST on BMD have demonstrated conflicting results [2–5]. There is insufficient guidance regarding the degree and duration of TSHST in the context of skeletal effects despite multiple existing guidelines.

Aim

To conduct a retrospective review of the current management of the skeletal effects of DTC patients against current guidelines.

Methods

Data was collected on patients with DTC on TSHST from the Liverpool University Hospital database in the last 15 years.

Results

73% (45/62) of patients with DTC aged between 21 to 85 years were included in the study. 42% (19/45) including 5 men, 4 pre-menopausal women and 10 postmenopausal women had at least one DEXA scan whereas 58% (26/45) had no DEXA. Only 31.6% (6/19) had two or more DEXA scans. Average time from starting TSHST to first DEXA was 4.5 years (sd 4.5). 60% (6/10) of patients within 12 months of surgery and radioiodine treatment had a recorded TSH level with only 50% (3/6) having a TSH level < 0.1 mu/l as recommended by the British Thyroid Association(BTA)[6]. All pre-menopausal women had a single normal DEXA with 75% (3/4) on vitamin D. All men had osteopenia with 66.7% (2/3) showing optimal vitamin D levels on replacement and 1/3 with inadequate levels. 40% of post-menopausal women with osteopenia were on vitamin D and 10% with osteoporosis on bisphosphonates. 50% (5/10) of post-menopausal women had TSH levels of < 0.05 for > 5 years (average 12.8 years, sd 1.1) but no documented FRAX as recommended by BTA[6]. A retrospective risk stratification using the Sheffield Fracture Risk Assessment (FRAX) tool [7] showed the average risk of a major and hip fracture in post-menopausal women was higher at 10.6% and 2.4% respectively compared to 5.1% and 1.5% in men. 22.2% (2/9) of post-menopausal women met the treatment threshold.

Conclusion

This study highlights important factors in the surveillance and management of skeletal effects. Achieving optimal TSH suppression and monitoring long-term skeletal effects of TSHST would be more effectively achieved by establishing local protocols specifying frequency of blood tests (thyroid function test, vitamin D levels), individual target TSH ranges and introducing the FRAX tool. This would identify at risk patients, determine timing of DEXA scans and guide treatment in the appropriate age group.