Hypercalcemia, hypercalciuria and nephrocalcinosis in a breast-fed term newborn : a rare presentation

Although hypercalcemia and hypercalciuria are known to occur in breast-fed preterm infants, to the best of our knowledge, it has never been reported in a term baby previously. We report a term male baby who was followed-up during pregnancy for having bright kidneys, but a follow-up renal ultrasound (US) after birth had revealed normal scan. Laboratory investigations revealed normal serum calcium (Ca), phosphorous (PO4) and alkaline phosphatase (ALP). The baby was being fed by breast milk. Follow-up US two months later showed early nephrocalcinosis along with hypercalcemia and hypercalciuria ; by the age of three months, nephrocalcinosis was more extensive and the serum Ca level was more than 12 mg / L with hypercalciuria. Parathyroid hormone (PTH), phosphorous (PO4), ALP and thyroid function tests were all normal. Antenatal history revealed a hypothyroid mother who was maintained on Lthyroxin, calcium and vitamin D supplement during pregnancy. Her blood tests showed normal serum Ca, low PO4 and elevated PTH. The baby was diagnosed to have hypercalciuria and hypercalcemia secondary to maternal hypophosphatemia (maternal vitamin D deficiency). Breast feeding was stopped and the baby was started on formula, whereby he showed remarkable improvement both for his blood chemistry as well as his hypercalciuria.