ESPE Abstracts

Background: Symptoms of hypocalcaemia in neonates are nonspecific, including irritability, fine tremors and seizures or sudden death due to arrhythmias. Transient hypoparathyroidism is common in the first days of life in preterm infants. Permanent hypoparathyroidism is primarily due to genetic or autoimmune factors, with post-surgery or infiltration-related forms being rare in pediatrics.

Case Presentation: A baby was born at 26 weeks from pregnancy complicated by gestational diabetes, and pre-existent hypoparathyroidism under replacement therapy. He showed bronchodysplasia, jaundice, anemia, retinopathy, and steroid-induced hypertrophic cardiomyopathy. {From the first days of life, intermittent clonic movements and tremors were observed, associated with low levels of plasma calcium. Electroencephalograms and electrocardiogram were normal. Severe hypocalcaemia was refractory to high dose of intravenous calcium and vitamin D supplementation. Parathyroid hormone (PTH) was undetectable, and treatment with oral 10% calcium gluconate, alfacalcidol (active vitamin D metabolite) and magnesium was initiated. During hospitalization, serial checks of the calcium-phosphorus balance showed persistent hypocalcaemia, undetectable PTH, borderline levels of phosphatemia, elevated urinary calcium/creatinine ratio (Ca/Cr-ratio) and alkaline phosphatase (ALP). On the 81^st day of life, due to the constantly altered Ca/Cr-ratio, a renal ultrasound was performed, revealing bilateral nephrocalcinosis. Treatment with potassium citrate was initiated, leading to gradual improvement of the condition. Due to the borderline levels of phosphorus, elevated ALP and tubular reabsorption of phosphates, prematurity-related osteopenia was suspected. Therefore, on the 94^th day of life, treatment with esafosfina was initiated. Osteopenia was never confirmed radiologically. The treatment allowed for an improvement in the renal balance. However, the therapeutic management of the patient became more challenging with the introduction of esafosfina, which led to a further decrease in serum calcium levels (minimum peak 6.3 mg/dL) and restart of clonic movements. Thus, it was decided to discontinue it and further adjust the dosage of oral calcium gluconate (maximum 12 ml die). Calcium levels improved, but PTH was still undetectable. Considering the positive maternal family history of hypoparathyroidism, genetic analysis was performed and showed a variant of unknown significance (c.359T>C) in CASR gene, located in a highly conserved domain of the protein. Genetic analysis on parents is still ongoing.