From the Guidelines
DiGeorge syndrome patients should receive daily calcium and vitamin D supplementation to manage hypocalcemia, with a target calcium level in the low-normal range (8.5-9.0 mg/dL), as recommended by the most recent guidelines 1.
Management of Hypocalcemia
The management of hypocalcemia in DiGeorge syndrome involves calcium supplementation, typically with oral calcium carbonate 1000-2000 mg elemental calcium daily in divided doses, along with active vitamin D (calcitriol) 0.25-1 mcg daily to enhance calcium absorption.
- Regular monitoring of serum calcium, phosphorus, magnesium, and vitamin D levels is essential.
- Patients should be educated about hypocalcemia symptoms including tingling, muscle cramps, and seizures.
- For severe symptomatic hypocalcemia with tetany, seizures, or cardiac arrhythmias, intravenous calcium gluconate 10% solution (1-2 ampules) should be administered immediately, followed by continuous calcium infusion until oral therapy is established.
Underlying Cause
The hypocalcemia in DiGeorge syndrome results from hypoparathyroidism, as the parathyroid glands develop from the third and fourth pharyngeal pouches, which are affected by the genetic deletion (typically 22q11.2) that causes this syndrome 1.
- This genetic deletion can lead to a range of other manifestations, including cardiac defects, immunodeficiency, and developmental delays.
- Long-term management requires a multidisciplinary approach to address these potential manifestations.
Monitoring and Prevention
Regular investigations, including measurements of pH-corrected ionized calcium, magnesium, parathyroid hormone, and creatinine concentrations, are recommended 1.
- Targeted monitoring of calcium concentrations should be considered at vulnerable times, such as peri-operatively, perinatally, or during severe illness.
- Caution is advised with respect to over-correction, which can result in iatrogenic hypercalcemia, renal calculi, and renal failure.
From the Research
DiGeorge Syndrome and Hypocalcemia
- DiGeorge syndrome is a genetic disorder characterized by multisystem involvement, including craniofacial and cardiac anomalies, and parathyroid and immune system dysfunction 2.
- Hypocalcemia is a common feature of DiGeorge syndrome, resulting from hypoparathyroidism, which can lead to seizures and other complications 3, 4, 5.
- Studies have shown that patients with DiGeorge syndrome often develop hypocalcemia, which can be severe and require calcium supplementation 2, 4, 5.
- The incidence of hypocalcemia in DiGeorge syndrome can be attributed to the deletion of chromosome 22q11.2, which affects the development of the parathyroid glands 4, 5.
- Hypocalcemia can also be induced by maternal vitamin D deficiency in infants with DiGeorge syndrome, highlighting the importance of prenatal care and vitamin D supplementation 6.
Clinical Presentation
- Hypocalcemia in DiGeorge syndrome can present with a range of symptoms, including seizures, stridor, and cardiac anomalies 2, 3, 5, 6.
- Afebrile seizures can be an initial symptom of hypocalcemia in children with DiGeorge syndrome, emphasizing the need for serum electrolyte level measurement in patients presenting with seizures 3.
- The clinical presentation of DiGeorge syndrome can be variable, making diagnosis often missed or underdiagnosed 6.
Management and Treatment
- Patients with DiGeorge syndrome often require prolonged respiratory and hemodynamic support, and may need calcium supplementation to manage hypocalcemia 2.
- Immunodeficiencies associated with DiGeorge syndrome may increase the risk of postoperative infections, highlighting the need for specific transfusion management practices 2.
- Early diagnosis and treatment of hypocalcemia are crucial to prevent long-term complications and improve outcomes in patients with DiGeorge syndrome 3, 4, 5, 6.