Familial hypocalciuric hypercalcemia (FHH) is a group of autosomal dominant disorders caused by dysfunction of the calcium sensing receptor (CaSR) and its downstream signaling proteins, leading to generally asymptomatic hypercalcemia. During pregnancy, distinguishing FHH from primary hyperparathyroidism (PHPT) is important, as the latter is associated with adverse outcomes and can be treated surgically during pregnancy, whereas the former is benign. This case report highlights the difficulties in diagnosing FHH during pregnancy. A 32‐year‐old woman was found to have asymptomatic hypercalcemia at 14‐weeks’ gestation. Investigations showed a corrected calcium (cCa) of 2.61 mmol/L (2.10 to 2.60), ionized Ca (iCa) of 1.40 mmol/L (1.15 to 1.28), 25OHD of 33 nmol/L (75 to 250), and PTH of 9.5 pmol/L (1.5 to 7.0). The patient was treated with 2000 IU cholecalciferol daily with normalization of 25OHD. The urine calcium / creatinine clearance ratio (CCCR) was 0.0071, and neck US did not visualize a parathyroid adenoma. Upon a retrospective review of the patient's biochemistry from 2 years prior, hypercalcemia was found that was not investigated. The patient was monitored with serial iCa levels and obstetric US. She delivered a healthy boy at 38‐weeks’ gestation. Postnatal iCa was 1.48 mmol/L and remained elevated. Her son had elevated iCa at birth of 1.46 mmol/L (1.15 to 1.33), which rose to 1.81 mmol/L by 2 weeks. He was otherwise well. Given the familial hypercalcemia, a likely diagnosis of FHH was made. Genetic testing of the son revealed a missense mutation, NM_000388.3(CASR):c.2446A > G, in exon 7 of the CaSR, consistent with FHH type 1. To our knowledge, there are only three existing reports of FHH in pregnancy. When differentiating between FHH and PHPT in pregnancy, interpretation of biochemistry requires an understanding of changes in Ca physiology, and urine CCCR may be unreliable. If the decision is made to observe, clinical symptoms, calcium levels, and fetal US should be monitored, with biochemistry and urine CCCR performed postpartum, once lactation is completed © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Aboriginal and Torres Strait Islander women have high rates of gestational diabetes (GDM). The Pregnancy And Neonatal Diabetes Outcomes in Remote Australia (PANDORA) study is a prospective longitudinal cohort of women with type 2 diabetes (T2D), GDM or normoglycemia in pregnancy in the Northern Territory, Australia. In this analysis we report progression to prediabetes and T2D at 2.5 years [range 2.1, 3] postpartum in a subgroup of Aboriginal and Europid women with GDM and normoglycemia in pregnancy (n=337). Women with pre-existing T2D were excluded. Data were analysed using Fisher’s exact tests. Among Aboriginal women with GDM we assessed predictions for progression using multivariate logistic regression. Aboriginal women with GDM (n=111) were younger than Europid women with GDM (n=104) (29 years (SD 5.9) vs. 32 (5.6) p<0.01), with similar first trimester BMI (28.9 kg/m2 (SD 7.2) vs. 28.5 (6.7) p=0.64). Of Aboriginal women with GDM, 24 (22%) progressed to T2D and 12 (11%) to prediabetes. Of Aboriginal women with normoglycemia (n=60), 1 (2%) progressed to T2D and 1 (2%) to prediabetes (p<0.01 for combined outcome vs. GDM women). Of Europid women with GDM, none progressed to T2D and 4 (4%) to prediabetes and of those with normoglycemia (n=62) none progressed to diabetes or prediabetes (p=0.09 vs. GDM women). Among Aboriginal women with GDM, factors associated with postpartum diabetes or prediabetes were age (OR 1.11, 1.03-1.2) and, after adjusting for age: severity of GDM (higher fasting plasma glucose (per 1 mmol/L OR 2.11, 1.23-3.62), use of insulin (OR 3.20, 1.35-7.6)) and higher first trimester BMI (per 3 kg/m2 OR 1.22, 1.01-1.47). Not smoking was protective (OR 0.35, 0.14-0.90), although any breastfeeding at 6-months postpartum was not (OR 0.95, 0.36-2.47). To our knowledge this is the only prospective study of Aboriginal and Torres Strait Islander women with GDM. We report the highest rates in the world of T2D after GDM at 2.5 years postpartum, highlighting a need for targeted interventions in this high-risk population. Disclosure A. Wood: None. J. Boyle: None. F. Barzi: None. E.L. Barr: None. M.J.I. Hare: None. A. Titmuss: None. E. Death: None. M. Kirkwood: None. A. Simmonds: None. E.M. Moore: None. J. Oats: None. D. McIntyre: Other Relationship; Self; Novo Nordisk A/S. P.Z. Zimmet: None. A.D. Brown: None. J.E. Shaw: Advisory Panel; Self; AstraZeneca, Merck Sharp & Dohme Corp., Mylan, Sanofi. Research Support; Self; AstraZeneca. Speaker’s Bureau; Self; Eli Lilly and Company, Mylan. L.J. Maple-Brown: None.