SUN-783 - Pregnancy- and Lactation-Associated Osteoporosis: Clinical Observations from A Case Series

INTRODUCTION
We describe 4 cases of pregnancy and lactation-associated osteoporosis (PLAOP), an uncommon but potentially devastating condition, most often presenting with vertebral fractures. Less commonly, it may present with hip fractures. Diagnosis is often delayed as symptoms are attributed to normal changes of pregnancy. Risk factors for PLAOP are similar to those of premenopausal osteoporosis (PreMOP). Pathogenesis and optimal management are not yet well defined in literature.

CASE PRESENTATION
Case 1- 30 year old woman with BMI 21 kg/m2 presented with back pain 2 months postpartum after her first pregnancy. MRI spine showed compression fracture at L1. Bone mineral density (BMD) or lowest Z score was -2. Other risk factors for osteoporosis included Factor V Leiden deficiency (treated with warfarin and switched to lovenox in pregnancy). She was treated with teriparatide for 5 months and Denosumab for 5 years.

Case 2- 26 year old woman with BMI 21 kg/m2 presented with back pain 2 months postpartum after her first pregnancy. MRI spine showed L2-L5 compression fracture. BMD or lowest Z score was -2.4. She was advised to stop lactation and was treated with calcium and vitamin D.

Case 3- 28 year old woman with BMI 25 kg/m2 presented with back pain during her second pregnancy. MRI spine showed fractures in T6-T12. She had no other risk factors for osteoporosis. BMD was not performed due to pregnancy. She was treated with calcium and vitamin D.

Case 4- 31 year old woman with BMI 22 kg/m2 presented with groin pain during her first pregnancy. Radiographs showed non displaced fracture of femoral neck, and no vertebral fractures. BMD was not performed due to pregnancy. She had no other risk factors for osteoporosis. She was treated with Zoledronic acid.

In all four cases, fractures occurred without antecedent trauma, and no further fractures occurred in the future.

DISCUSSION
PLAOP is a rare condition affecting ~0.45/100,000 pregnancies and shares many features of pre-menopausal osteoporosis (PreMOP) of young women and idiopathic osteoporosis (IOP) of young men. However, unlike the other 2 types of osteoporosis, PLAOP is usually self-limited, without recurrence during subsequent pregnancies. BMD is usually normal unlike PreMOP and IOP.

As can be expected, almost all cases of PLAOP occur before age 35 years and PreMOP occur after age 40 years. Pathogenesis of PLAOP is distinct from PreMOP and IOP without BMD or bone volume deficits or osteoblast dysfunction.

Among our cases, none of the women had recurrence of fractures. Three of four women had vertebral fractures, and one woman had a non-displaced femoral neck fracture; all occurred during or immediately after pregnancy. One of the cases occurred in the second pregnancy, while three were in the first pregnancy.

There are no known identifiable risk factors and no clinical trials addressing optimal management of PLAOP; further research is warranted.

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