Endocrine Abstracts

Hypercalcaemia during pregnancy is unusual and primary hyperparathyroidism is the commonest cause: we present a more unusual case.

Case history: 29-year woman, 34 weeks pregnant, was admitted with hypertension and oedema. She had gestational diabetes managed with diet alone. Initial calcium level was normal; it gradually increased in the next few days though this was not noted. She was diagnosed with preeclampsia and treated with steroids for foetal lung maturation. Calcium level normalized after steroids but on the day of delivery was 2.74. She had an induced vaginal delivery at 35 weeks. 6 days later she was readmitted due to high blood pressure. Calcium on admission was 3.09. This was treated with iv fluids and then, when calcium rose to 3.19, a dose of pamidronate. She felt well and her only symptom was constipation. Examination was normal except for a flow murmur. Calcium fell into the normal range 2 weeks after pamidronate and remained normal subsequently. She was on 400 units of Vitamin D supplements as per RCOG guidelines, during pregnancy.

Investigations: PTH was 12 (15–60) and 25-OH vitamin D was 115.8 reflecting supplementation. Serum ACE was normal A PTHrP was undetectable, however this was taken 21 days after delivery. A low dose CT scan of chest Abdo-pelvis was done to rule out occult malignancy: this was normal except focal thickening of the gall bladder wall which ultrasound suggested was adenomyomatosis.

Results and treatment: Calcium remained normal during puerperium after treatment with a single dose of pamidronate.

Conclusions and points for discussion: A diagnosis of humoral hypercalcaemia of pregnancy was made in this case based on the acute rise in late pregnancy, suppressed PTH, and no malignant cause found. We feel vitamin D toxicity is less likely as she was not on high dose of Vitamin D supplementation. Vitamin D binding protein levels increases during pregnancy showing elevated levels of 25(OH)Cholecalciferol. Placental PTHrP production is thought to drive this unusual condition: unfortunately, we could not test PTHrP during the puerperium. Recurrence risk for this condition is not known and we have recommended monitoring of calcium levels in her next pregnancy.