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

Although hypercalcemia and hypercalciuria are known to occur in breast-fed pre-term 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 L-thyroxin, 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.