Endocrine Abstracts

Background: Vitamin D deficiency is recognised as a global public health concern, with a prevalence of 20–25% in the general population. In infants, intrauterine deficiency can significantly impact growth, immune function, and neurodevelopmental outcomes.

Case presentation: 6-week-old infant presented to hospital with poor weight gain and recurrent vomiting. Born at 39+6 weeks, with a birth weight of 2.54 kg. Mother had anaemia during pregnancy, requiring blood transfusion. Initial investigations revealed hypomagnesemia, which was corrected. Abdominal ultrasound and brain MRI were normal, in echocardiography patent foramen ovale, atrial septal defect for cardiology follow-up were reported. Dysmorphic features included low-set ears and a triangular face were noted and baby was referred to geneticists. At 8 weeks of age, patient was re-admitted due to persistent failure to thrive, with static weight and episodes of vomiting. Laboratory tests showed severe hypocalcaemia, hypomagnesemia, hypophosphatemia, markedly elevated parathyroid hormone (PTH), high alkaline phosphatase, and undetectable 25OH-vitamin D levels with low urine Ca/Cr ratio. Baby was admitted to HDU where required continuous intravenous calcium infusion for 23 days, magnesium correction and phosphate supplement along with oral cholecalciferol. Biochemical parameters were not improving with high calcium requirement, persistently elevated PTH and undetectable vitamin D levels and after 10 days alfacalcidiol was added and intramuscular ergocalciferol was given due to concerns of malabsorption. After 3 weeks of treatment 25OHD3 was detectable with decrease in PTH, intravenous calcium was weaned and calcium levels remained stable on oral supplement. Due to static weight special formula was prescribed. Post discharge, baby was gaining weight and laboratory results improved. During inpatient admission many specialities were involved including critical care, gastroenterology, metabolic team, dietetic team, biochemistry and genetic team. Genetic testing including R14 panel have not detected any pathological variants.

Conclusion: Intrauterine vitamin D deficiency can significantly impair fetal growth and mimic rare metabolic or genetic disorders. Early identification and prevention through routine supplementation during pregnancy along with neonatal supplementation, are crucial to optimise infant growth and development. This case highlights the importance of prioritising vitamin D sufficiency as a public health strategy beginning in pregnancy and continuing through early childhood.