E-Poster 63rd Endocrine Society of Australia Annual Scientific Meeting 2020

Cross-sectional determinants of hip and spine bone mineral density (BMD) and trabecular bone score (TBS) in a postpartum gestational diabetes (GDM) cohort. (#104)

Mawson Wang 1 2 , Allison Sigmund 1 , Susan Hendon 1 , Tien-Ming Hng 1 2 , Sue Lynn Lau 1 2
  1. Department of Endocrinology, Blacktown Hospital , Blacktown, NSW, Australia
  2. Blacktown Clinical School, School of Medicine, Western Sydney University, Sydney, NSW, Australia

BMD loss during the postpartum lactation period is driven by hypo-oestrogenism and calcium transfer into breastmilk. TBS is a parameter of bone microarchitecture, not previously studied in this population.  Population studies demonstrate positive BMD correlation with BMI, diabetes status and calcium intake, while TBS negatively correlates with BMI and diabetes status. We explored traditional and novel determinants of BMD and TBS z-scores at 3 months post-GDM pregnancy.

205 women completed anthropometric measurements, DXA scan, oral glucose tolerance test (OGTT) and lifestyle questionnaires at a mean (±SD) 11.0±2.5 weeks postpartum.

Mean z-scores and 95% confidence intervals for lumbar spine (LS) BMD (-0.58 [-0.71 to -0.44]), femoral neck (FN) BMD (-0.25 [-0.37 to -0.12]) and spine TBS (-0.36 [-0.51 to -0.22]) were below the expected age and weight-matched mean of zero. LS and FN BMD z-scores did not correlate with BMI and central fat percentage, whereas TBS z-score correlated with both BMI (r=0.31, p<0.01) and central fat (r=0.23, p<0.01).

BMD z-score did not differ between ethnicities. Subcontinental and Asian women exhibited lower TBS z-scores compared to Caucasian women (-0.72 vs. -0.54 vs. -0.09 respectively, p<0.01) but also had lower mean BMI (27.7 vs. 25.1 vs. 30.5 respectively, p<0.01). When analysed separately (Figure.1), the relationship between BMI and TBS z-score remained present in Caucasians (r=0.33, p<0.01) and almost reached significance in Asians (r=0.31, p=0.054).

There was no difference in LS BMD or TBS z-score between breastfeeding and formula-feeding women. BMD and TBS z-scores did not differ according to OGTT result, vitamin D status, dietary calcium intake or exercise intensity.

BMD and TBS z-scores were similarly low at 3 months postpartum. Ethnic differences in TBS z-scores have not been previously reported. Contrary to other studies, BMI positively associated with TBS but not BMD z-scores, partly modified by ethnicity. Other determinants of bone health were not identified.

 

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