Background.
Primary hyperparathyroidism (PHPT) and
Familial Hypocalciuric Hypercalcemia (FHH) result in different maternal and fetal complications in pregnancy.
Calcium to
creatinine clearance ratio (
CCCR) is commonly used to help distinguish these two conditions. Physiological changes in
calcium handling during pregnancy and lactation can alter
CCCR, making it a less useful tool to distinguish PHPT from FHH. Cases. A 25-year-old female presented with
hypercalcemia and an inappropriately normal PTH. Her
CCCR was 0.79% before pregnancy and rose to 1.99% in her second trimester. The proband's mother and neonate had asymptomatic
hypercalcemia. Genetic analysis revealed a CaSR mutation consistent with FHH. A 19-year-old female presented with a history of
nephrolithiasis who underwent emergent
caesarean section at 29 weeks of gestation for severe
preeclampsia. At delivery, she was diagnosed with
hypercalcemia with an inappropriately normal PTH and a
CCCR of 2.67%, which fell to 0.88% during lactation.
Parathyroidectomy cured her
hypercalcemia. Pathology confirmed a
parathyroid adenoma. Conclusion. These cases illustrate the influence of pregnancy and lactation on renal
calcium indices, such as the
CCCR. To avoid diagnostic error of women with
hypercalcemia during pregnancy and lactation,
calcium biochemistry of first-degree relatives and genetic testing of select patients are recommended.