P2.M252: Seizures in an Exclusively Breastfed 10-Month-Old Infant

Introduction: Hypocalcemia is defined as a serum calcium of ≤ 8 mg/dL or an ionized calcium of ≤ 4.4 mmol/L. Despite the AAP recommendation to supplement breastfed infants with vitamin D, cases of seizures due to vitamin D deficiency (VDD) still occur in high-risk infants such as those exclusively breastfed, premature, or with darker pigmentation.

Case Description: A 10-month-old African American male, born at 37 weeks with no complications, presented with cyanosis, apnea, and seizure. He went limp with perioral cyanosis after choking on feeds. His mother performed cardiopulmonary resuscitation and brought him to the hospital. He is exclusively breastfed with no vitamin D supplementation and minimal baby foods.

On arrival, he had a seizure-like episode and was given Ativan. He was placed on oxygen via nasal cannula for respiratory distress and adenoid hypertrophy and given fluids, antibiotics, steroids, and Tamiflu. Partial septic work up, urine drug screen, head CT, and electroencephalogram were obtained which were significant for calcium of < 5 mg/dL, ionized calcium of 0.64 mmol/L, alkaline phosphatase of 823 U/L, and Flu A. Other studies were normal (Table 1).

For low calcium levels, multiple doses of intravenous calcium gluconate were given until serum levels normalized. 25-OH Vitamin D level was < 4.2 ng/mL (normal: 20 ng/mL), and PTH was appropriately elevated at 316.8 pg/mL. His initial presentation was attributed to hypocalcemia secondary to severe nutritional VDD. He was started on high dose vitamin D supplementation after serum calcium was stable for 48 hours and then started on oral calcium supplementation. Bilateral wrist and knee x-rays showed clinical findings of rickets (Figure 1). Work up for malabsorption, autoimmune conditions, and kidney disorders including celiac, thyroid, parathyroid, and urine studies was negative. He was discharged home on oral calcium carbonate (100-120 mg of elemental calcium/kg/day) and vitamin D (2000 IU/day).

Discussion: Hypocalcemia can cause seizures, apnea, poor feeding, tetany, laryngospasm, cyanosis, and impaired cardiac function, for which prompt normalization of serum calcium levels is required with intravenous supplementation. VDD should always be considered, especially in those with risk factors like breastfeeding, prematurity, and darker pigmentation. The most common causes of VDD include nutritional deficiency, celiac disease, pancreatic insufficiency, and liver dysfunction. If rickets are present, they require long-term calcium and vitamin D supplementation with nutritional counseling and serial follow-ups.

Conclusion: This was a breastfed infant with hypocalcemia from severe VDD with seizures. Prompt repletion of calcium is required, then long-term supplementation of both calcium and vitamin D along with nutritional counseling is needed to resolve rickets. This case brings awareness to providers to recognize the presentation of VDD and the importance of vitamin D supplementation in high-risk populations.