SHM Converge Scientific Abstract ePoster Gallery-"How Low Can You Go?": A 7-Month-Old Boy With Seizures and Hypocalcemia

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A previously healthy 7-month-old boy presented with a new 10-minute seizure. He had been exclusively breastfed until 2 weeks before admission, then switched to formula and solid foods, with decreased oral intake. He had not received vitamin supplementation. There were no fever, respiratory, or recent infectious symptoms.<br /><br />Evaluation showed severe hypocalcemia and hyperphosphatemia: serum calcium 5.9 mg/dL, ionized calcium 2.82 mg/dL, and phosphorus 10.8 mg/dL. Parathyroid hormone was inappropriately normal at 42.5 pg/mL, and 25-OH vitamin D was profoundly low at 4.8 ng/mL. Physical exam was otherwise normal, with no signs of rickets or neuromuscular irritability.<br /><br />The main differential for infant hypocalcemia includes disorders of parathyroid hormone (PTH) regulation and vitamin D deficiency. In this case, the lab pattern supported hypoparathyroidism despite coexisting vitamin D deficiency. Further testing ruled out other causes, and imaging of the wrists and knees showed no bony abnormalities. Cytogenetic testing revealed an interstitial deletion of chromosome 10 involving the GATA3 gene, confirming HDR syndrome (hypoparathyroidism, sensorineural deafness, and renal disease).<br /><br />The child was treated with ergocalciferol, calcium carbonate, and calcitriol, leading to normalization of calcium and vitamin D levels by 6-week follow-up. The case emphasizes that severe infant hypocalcemia with elevated phosphorus and a non-elevated PTH should prompt evaluation for hypoparathyroidism, including genetic causes when acquired etiologies are excluded.

Asset Subtitle

Ashmita Chatterjee

Meta Tag

Author List Ashmita Chatterjee, Erin Cook, Indraneel Prabhu, John R. Stephens

Category Clinical Vignettes

Concept Hypocalcemia

Concept Seizure

Concept Parathyroid Hormone

Concept Vitamin D

Concept Hypoparathyroidism

Distinguished Non-Finalist

Presenter Organization Unc

Presenting Author Ashmita Chatterjee

Track Pediatric

Keywords

infant hypocalcemia

seizure

hypoparathyroidism

vitamin D deficiency

hyperphosphatemia

GATA3 deletion

HDR syndrome

calcium carbonate

calcitriol

ergocalciferol

Hypocalcemia

Seizure

Parathyroid Hormone

Vitamin D

Hypoparathyroidism