Milk-alkali syndrome is a rare cause of hypercalcaemia characterised by the triad of hypercalcaemia, metabolic alkalosis and renal insuffiency associated with the ingestion of calcium and absorbable alkali. It is an uncommon cause of severe hypercalcaemia in pregnancy, with less than 10 cases reported in the literature. 1,2
We report the case of a 33-year-old primigravida who presented at 33+1/40 with a 1-week history of nausea, vomiting, severely reduced oral intake, epigastric pain, reflux and constipation. Her initial bloods showed severe hypercalcaemia (corrected calcium of 3.60mmol/L), an acute kidney injury (Cr 99umol/L) and a metabolic alkalosis (pH 7.64, pCO2 39mmHg, bicarbonate of 41mmol/L). Hypochloraemia, hypomagnesaemia and hypokalaemia were present. She had a normal calcium level a few months prior. Her background is significant for class II obesity (BMI 35.0) and gastro-oesophageal reflux disease with worsening symptoms throughout her pregnancy, particularly in the days leading to her admission. She has no history of pancreatitis, fractures, or renal calculi. There was no family history of hypercalcaemia. Her medications included pantoprazole 40mg per day and ondansetron 4mg PRN. Further history revealed the consumption of 1-1.5 litres of milk and 8-10 tablets per day of the antacid Rennie. Each tablet contains 680mg of calcium carbonate resulting in a daily intake of elemental calcium between 3,800 and 4,300mg. Subsequent investigations revealed a low but not suppressed PTH (1.3pmol/L). Her serum ACE was normal. Her 1,25 hydroxyvitamin D was low at 27g/L. Her hypercalcaemia resolved with intravenous fluids and cessation of antacids. Her electrolytes were replaced. Her corrected calcium remained normal 1 week following her discharge from hospital.
This case highlights the potential harm of using excessive doses of over-the-counter calcium containing antacids in women who suffer from reflux in their pregnancy.
References
1. Kolnick L, Harris BD, Choma BP et al. Hypercalcaemia in pregnancy: a case of milk-alkali syndrome. J Gen Intern Med. 2011 Aug:26(8):939-42
2. Pocolos MK, Sims CR, Mastrobattista JM et al. Milk-alkali syndrome in pregnancy. Obstet Gynaecol. 2004 Nov;104(5 Pt 2): 1201-4.