Is there a difference in observed bone mineral density at diagnosis of overt or subclinical thyrotoxicosis?

Cathy McHugh; Paul Hession

doi:10.1530/endoabs.34.P420

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Endocrine Abstracts (2014) 34 P420 | DOI: 10.1530/endoabs.34.P420

SFEBES2014 Poster Presentations Thyroid (51 abstracts)

Is there a difference in observed bone mineral density at diagnosis of overt or subclinical thyrotoxicosis?

Cathy McHugh ¹ & Paul Hession ²

Err

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¹Sligo Regional Hospital, Sligo, Ireland; ²National University of Galway, Sligo, Ireland.

Introduction: Early thyrotoxicosis is associated reduced bone density. The aim of this study is to determine any difference between bone mineral density (BMD) in those presenting with overt or subclinical thyrotoxicosis.

Methods: Retrospective observational study of BMD in individuals presenting with thyrotoxicosis from 2008 to 2013. BMD was assessed by bone densiometry using T, Z, and total BMD within 1 year of first abnormal thyroid function tests.

Results: 91 people were included: 64 women and 27 men. 49 had overt thyrotoxicosis at diagnosis (n=15 aged 20–50 years, n=34 aged >50 years), 40 had subclinical thyrotoxicosis (five aged 20–50 years, 35 aged >50 years). The median age was 43 years (overt), 42 years (subclinical) aged 20–50 years, 58.5 (overt), 70 years (subclinical) in the >50 years group.

In those aged 20–40 years the mean TSH at diagnosis (n=20) was 0.03±0.02 U/ml, fT₄ 27.17±2.5 pmol/l, and in the >50 years age (n=69) mean TSH was 0.16±0.04 pmol/l, fT₄ 21.46±1.34 pmol/l. There was no difference in BMD, T or Z scores in overt or thyrotoxic patients in any of the age ranges.

In the 20–50 years age group 4 had a Z score <−2.5, two in L1L4 and two femoral neck (all subclinical). 12 had Z scores between −2.5 and −1.0 (two in L1L4 (two overt) and ten femoral neck (seven overt, three subclinical). Aged >50 years 30 had T scores <−2.5 (L1L4(ten overt, six subclinical) 12 femoral neck (six overt, six subclinical), two radius (subclinical), 84 had T scores −1.0 to −2.5 (L1L4 (seven overt, 12 subclinical), 64 femoral neck (35 overt, 29 subclinical) and one radius(subclinical).

Conclusion: There is no difference in Z score and T score between those who presented with overt thyrotoxicosis and those with subclinical thyrotoxicosis. There were a number with Z scores −2.5 to −1.0 which merit rescanning but overall the prevalence of lower T scores in those aged >50 years presenting with thyrotoxicosis was high and this was their first DEXA. This study highlights the importance of DEXA scanning in this population.