Introduction: We report an insidious presentation of hypocalcemic dilated cardiomyopathy (HDCM) in an infant with nutritional rickets and severe hypocalcemia, highlighting the myocardium’s strict reliance on calcium-phosphate homeostasis. Case: A 3-month-old, small-for-gestational-age male (birth weight: 1.93 kg), with congenital cataracts and persistent neonatal cholestasis (negative hepatopathy and congenital infection screens) presented acutely with post-feeding cyanosis, requiring intubation for aspiration pneumonia. The mother denied prior apneic episodes, seizures, feeding difficulties, or heart failure symptoms. Clinically, there was no murmur or hyperactive pericardium. Chest radiograph revealed globular cardiomegaly. Echocardiography confirmed HDCM (LVEF 41%). Bloodwork revealed profound hypocalcemia (1.16 mmol/L; normal 2.1–2.6), hyperphosphatemia (2.97 mmol/L), and markedly elevated alkaline phosphatase (2,411 IU/L). 25(OH)D3 was deficient (34.08 nmol/L). Secondary hyperparathyroidism (iPTH 19.55 pmol/L) represented an appropriate response. The mother had introduced goat’s milk instead of cow’s milk due to inadequate lactation. She took no supplements during pregnancy and was also vitamin D deficient. Management included IV calcium gluconate, targeted antifailure therapy (captopril, furosemide, spironolactone), and mechanical ventilation. High-dose cholecalciferol replenished depleted stores, alongside an active vitamin D analog (alfacalcidol) to bypass impaired hepato-intestinal pathways, stimulating calcium absorption. Extubated after 2 weeks with stabilized serum calcium, he was discharged on anti-failure therapy, oral calcium carbonate (54 mg/kg/day elemental), D-cure 25,000 IU 4-weekly, Ursodeoxycholic acid (45 mg 12-hourly), and multivitamins. Repeat echocardiography is planned at 3 months. Conclusion This case underscores the vulnerability to nutritional rickets and late-onset hypocalcemia in SGA infants with inadequate maternal nutrition and impaired GI absorption. The calcium-phosphate axis is easily disrupted; highphosphate substitutes (goat’s milk) precipitously unmask hypocalcemia, overwhelming compensatory hyperparathyroidism. Proactive, dual-therapy metabolic supplementation is paramount to avert catastrophic, yet reversible, HDCM.
Cardiomyopathies ; Rickets