We present a case of hypercalcemia in a 12-month-old female with Down syndrome. The patient presented with significant weight loss (810 g since her 6-month visit) and severe growth failure (weight 5.8 kg, -4.5 SDs). Laboratory evaluation revealed severe hypercalcemia with appropriately suppressed PTH and 1,25-hydroxyvitamin D levels. Renal ultrasound confirmed medullary nephrocalcinosis. After excluding common etiologies, the patient was diagnosed with hypercalcemia of Down syndrome, also termed Abnormal Calcium, Calcinosis, Creatinine in Down syndrome. Treatment with intravenous fluids, calcitonin, and transition to a low-calcium formula (Calcilo XD) normalized serum calcium levels. The patient maintained normal calcium levels on restricted dietary calcium intake for 7 months after discharge. This case adds to the limited literature on this rare but significant association, highlighting the importance of considering hypercalcemia in patients with Down syndrome presenting with growth failure. Although the pathophysiology remains unclear, a hyperabsorptive intestinal mechanism has been proposed. Early recognition and dietary calcium restriction are essential to prevent significant morbidity in affected children.

ABCD syndrome (ABnormal Calcium, Calcinosis, and Creatinine in Down syndrome) is characterized by an association of hypercalcemia, hypercalciuria, nephrocalcinosis, and impaired kidney function in patients with Down syndrome. Only 7 cases have been published worldwide, although it is believed to be underdiagnosed. This report describes 2 new patients with ABCD syndrome and compares them with the cases reported to date. Although it is a rare cause of pediatric hypercalcemia, it should be considered in children with Down syndrome once other more common etiologies have been ruled out. Once this diagnosis is confirmed, the recommended treatment is to reduce dietary calcium intake and work with an interdisciplinary team to maintain an adequate calorie and protein intake. El síndrome ABCD (por sus siglas en inglés, ABnormal Calcium, Calcinosis and Creatinine in Down syndrome) se caracteriza por la asociación de hipercalcemia, hipercalciuria, nefrocalcinosis y alteración de la función renal en pacientes con síndrome de Down. Existen solo 7 casos previamente publicados en el mundo, aunque se cree que está subdiagnosticado. En este reporte, presentamos 2 nuevos pacientes con este síndrome y realizamos una comparación con los casos informados hasta el momento. Si bien es una causa rara de hipercalcemia pediátrica, debe considerarse en niños con síndrome de Down una vez descartadas otras etiologías más frecuentes. Al confirmarse este diagnóstico, el tratamiento recomendado es la reducción de calcio en la dieta, trabajando de manera interdisciplinaria para mantener un aporte calórico proteico adecuado.

Abnormal calcium/calcinosis/creatinine in Down syndrome (ABCD syndrome) is a very rare condition with no clear etiology. In this paper, we describe our clinical encounter with this disease. We report the case of an 11-month-old male infant with Down syndrome (DS) who presented to the hospital with intractable vomiting and decreased oral intake and urine output. The evaluation revealed an acute kidney injury (AKI) and hypercalcemia. Although his AKI improved with intravenous hydration, his hypercalcemia persisted. Extensive studies were notable for an elevated urinary excretion of calcium and bilateral medullary nephrocalcinosis seen on renal ultrasound (US). As a result, he was diagnosed with ABCD syndrome. Dietary calcium restriction was implemented. During his follow-up visit with a pediatric endocrinologist, his serum calcium was found to be normalized. To our knowledge, this is only the seventh case report on ABCD syndrome in the literature.