From the Guidelines
The management of an infant with neonatal hypocalcemia and hyperphosphatemia should begin with a thorough evaluation for hypoparathyroidism, which is the most likely diagnosis, and initial workup should include serum parathyroid hormone (PTH), 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, magnesium, and urinary calcium and phosphate levels, as recommended by the espghan/espen/espr/cspen guidelines on pediatric parenteral nutrition 1.
Initial Evaluation and Workup
The initial evaluation should focus on identifying the underlying cause of hypocalcemia and hyperphosphatemia, with a particular emphasis on hypoparathyroidism. This includes:
- Serum parathyroid hormone (PTH) levels to assess parathyroid function
- 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels to evaluate vitamin D status
- Magnesium levels, as hypomagnesemia can contribute to hypocalcemia
- Urinary calcium and phosphate levels to assess renal excretion and reabsorption
Treatment Approach
Treatment should be tailored to the underlying cause and severity of the condition. For acute symptomatic hypocalcemia, calcium supplementation with calcium gluconate 10% at 1-2 mL/kg IV slowly is recommended, followed by oral calcium supplementation at 50-75 mg/kg/day of elemental calcium divided into 3-4 doses. Additionally, calcitriol (active vitamin D) should be initiated at 0.05-0.1 mcg/kg/day divided twice daily to enhance intestinal calcium absorption. Phosphate binders such as calcium carbonate may be necessary if hyperphosphatemia persists.
Monitoring and Adjustments
Regular monitoring of serum calcium, phosphate, magnesium, and urinary calcium excretion is crucial, with a target serum calcium in the low-normal range (8.5-9.5 mg/dL) to avoid hypercalciuria and nephrocalcinosis. Adjustments to treatment should be made based on laboratory results and clinical response. Genetic testing should be considered for DiGeorge syndrome, autoimmune polyglandular syndrome, or other genetic causes of hypoparathyroidism, as recommended by the guidelines 1.
Key Considerations
- The risk of precipitation of Ca-P-salts in parenteral nutrition should be considered, and stability, compatibility, and solubility of minerals should be tested by the local pharmacy 1.
- Monitoring of plasma phosphate concentration is critical, especially in preterm infants on parenteral nutrition, to prevent severe hypophosphatemia and its complications 1.
From the FDA Drug Label
Infants born to mothers with hypocalcemia can have associated fetal and neonatal hyperparathyroidism, which in turn can cause fetal and neonatal skeletal demineralization, subperiosteal bone resorption, osteitis fibrosa cystica and neonatal seizures Infants born to mothers with hypocalcemia should be carefully monitored for signs of hypocalcemia or hypercalcemia, including neuromuscular irritability, apnea, cyanosis and cardiac rhythm disorders.
The further workup and management for an infant with neonatal hypocalcemia and hyperphosphatemia include:
- Careful monitoring for signs of hypocalcemia or hypercalcemia, including neuromuscular irritability, apnea, cyanosis, and cardiac rhythm disorders.
- Evaluation for fetal and neonatal hyperparathyroidism and its potential complications, such as skeletal demineralization, subperiosteal bone resorption, osteitis fibrosa cystica, and neonatal seizures 2.
From the Research
Further Workup and Management
The further workup and management for an infant with neonatal hypocalcemia and hyperphosphatemia involve several steps:
- Checking the serum total or ionized calcium levels to confirm the diagnosis of hypocalcemia 3
- Investigating the etiology of hypocalcemia, which may include excessive phosphate intake, hypomagnesemia, hypoparathyroidism, and vitamin D deficiency 3, 4
- Monitoring serum calcium and phosphate levels regularly to assess the response to treatment 3
- Treating hypocalcemia according to its etiology, with calcium replacement being the cornerstone of treatment 3
- Considering the use of calcium supplements, calcitriol, low phosphorus formula, and magnesium supplementation in the management of hypocalcemia 5
Laboratory Investigations
Laboratory investigations that may be helpful in the further workup of an infant with neonatal hypocalcemia and hyperphosphatemia include:
- Serum calcium and phosphate levels to assess the severity of hypocalcemia and hyperphosphatemia 3, 4
- Intact parathyroid hormone (PTH) levels to evaluate for hypoparathyroidism 6, 7
- Magnesium levels to assess for hypomagnesemia 3, 4
- Vitamin D levels to evaluate for vitamin D deficiency 5
- Alkaline phosphatase activity to assess for bone disease 6
Treatment Options
Treatment options for an infant with neonatal hypocalcemia and hyperphosphatemia may include: