Poster Presentation Australasian Diabetes in Pregnancy Society Annual Scientific Meeting 2019

Pregnancy and lactation-associated osteoporosis: a rare cause of postpartum lower back pain (#41)

Kay Hau Choy 1 , Minoli Abeysekera 1 , Shailja Tewari 1
  1. Department of Endocrinology and Metabolism, Concord Repatriation General Hospital, Concord, NSW, Australia

Case: A 28-year-old five months postpartum female—who was exclusively breastfeeding her child—presented with atraumatic back pain which started one month postpartum. She was tender over the T12/L1 region. Radiograph demonstrated T12 vertebral crush fracture with >20% height loss. A dual-energy X-ray absorptiometry (DXA) showed T-scores of -1.2 standard deviation (SD) and -2.4 SD at the left femoral neck and L1-L4 spine respectively, with T-score of -2.7 SD at L2, in keeping with osteoporosis. She took no regular medication. There was no personal or family history of metabolic bone disorder. She was vitamin D replete but dairy intake was suboptimal. Workup for secondary osteoporosis showed thyrotoxicosis due to postpartum thyroiditis. The patient was diagnosed with pregnancy and lactation-associated osteoporosis (PLO), although her hyperthyroidism could also contribute to bone loss. She was commenced on calcium supplementation and was recommended to increase dairy intake. She was encouraged to wean breastfeeding. There was an improvement in her pain at one-month follow-up.

Discussion: PLO is uncommon, with a predilection for primiparous females in the third trimester or post-partum.1,2 DXA scans generally show lower bone densities at the spine compared with the femur due to increased trabecular bone resorption.1,3 Therefore, a common complaint includes back pain secondary to vertebral fractures.2,4 PLO can be associated with traditional osteoporosis risk factors,2 though other pathophysiological mechanisms include hypoestrogenism secondary to hyperprolactinaemia, release of parathyroid hormone-related peptide from breast and placenta, and increased lordosis and inactivity in pregnancy.5 The first-line management includes calcium plus vitamin D supplementation and cessation of breastfeeding.1,2 Bone density generally improves without specific pharmacotherapy,6 usually 6-12 months after weaning.3 Antiresorptives and teriparatide—which are second-line therapies—have shown efficacy in improving bone density, but concerns regarding long-term safety in young females and effect on future pregnancies remain.5,7 PLO should be considered in young pregnant or postpartum women with persistent back pain or spontaneous fragility fractures, as early recognition is essential in preventing debilitating morbidity.

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