Hypercalcaemia during pregnancy is uncommon, and mostly associated with primary hyperparathyroidism (pHPT). If unrecognised, it poses a significant risk for the mother and the foetus. Maternal symptoms include: hyperemesis, muscle weakness, pancreatitis, nephrolithiasis, bone disease, mental status changes, and hypercalcaemic crisis. Untreated disease complicates foetal development and foetal death is a significant risk. Our case illustrates the difficulty in detecting pHPT during pregnancy, serious complications connected with severe hypercalcaemia, and difficulties in preparing the patient for surgical treatment. Our review of the medical literature did not identify any previous case of a pregnant woman with hypercalcaemic crisis (total calcium 17 mg/dL, parathyroid hormone 2302 pg/mL), acute pancreatitis caused by pHPT, and with hyperthyroidism, who had undergone a successful surgical treatment.