Protean presentation and multiple challenges of nephrocalcinosis in pregnancy (six pregnancies in four patients)

Nephrocalcinosis is an umbrella term covering increased content of calcium salts in the renal parenchyma, interstitial damage and potential evolution towards renal failure. Pregnancy is often the first occasion for biochemical or imaging tests in young women and may allow early diagnosis. Conversely, even mild kidney disease may represent a challenge in pregnancy. The aim of this study was to report on four patients in whom nephrocalcinosis was first diagnosed during pregnancy, exemplifying the protean presentation and multiple challenges of nephrocalcinosis in pregnancy. This is a case series study including data on all pregnancies prospectively gathered in the Nephrological-Obstetric Unit dedicated to pregnancy and kidney diseases (2000-11). Six pregnancies were observed in four patients (31-35 years; one twin pregnancy, one ongoing, one patient with three pregnancies). Symptoms were oedema in two (later developed in a further patient), renal functional impairment and electrolyte imbalance in two each. Two patients developed hypertension late in pregnancy. Electrolyte imbalance was life-threatening in one patient (severe acidosis, severe hyperkalaemia: 7.5 mEq/L). Delivery was by Caesarean section in three patients, preterm in one. Multiple or long hospitalizations for metabolic reasons were needed in three patients, the fourth was hospitalized for obstetric reasons. In all patients, diagnosis of nephrocalcinosis was made at ultrasounds during basic nephrological evaluation, confirmed at computerized tomography scan in three. The pathogenesis was linked to diuretic abuse in one case and to collagen disease, inborn errors and prematurity, possibly associated with diuretic misuse, in the others. Nephrocalcinosis may have protean presentations in pregnancy. The risk of severe electrolyte derangements, oedema and hypertension warrants strict clinical surveillance.