From the Guidelines
The workup for hypocalcemia should begin with confirming true hypocalcemia by measuring ionized calcium or correcting total calcium for albumin levels, as recommended by the most recent guidelines 1. Initial laboratory tests should include:
- Serum phosphorus
- Magnesium
- Creatinine
- Parathyroid hormone (PTH)
- 25-hydroxyvitamin D
- Albumin An elevated PTH suggests secondary hyperparathyroidism due to vitamin D deficiency, chronic kidney disease, or malabsorption, while a low or inappropriately normal PTH indicates hypoparathyroidism. Additional tests may include:
- Urinary calcium excretion
- Alkaline phosphatase
- Thyroid function tests For acute symptomatic hypocalcemia, administer IV calcium gluconate 1-2 g over 10-20 minutes, followed by a continuous infusion of 0.5-1.5 mg/kg/hr while monitoring serum calcium every 4-6 hours, as supported by recent studies 1. For chronic management, oral calcium supplements (1-3 g elemental calcium daily divided into 2-3 doses) and vitamin D supplementation (calcitriol 0.25-1 mcg daily) are typically needed, with consideration of individualized approaches to treat hypocalcemia rather than recommending correction of hypocalcemia in all patients 1. Magnesium deficiency should be corrected if present, as it can impair PTH secretion and action. The underlying cause of hypocalcemia must be addressed for effective long-term management, whether it's vitamin D deficiency, hypoparathyroidism, chronic kidney disease, or other conditions affecting calcium homeostasis, as emphasized in the latest clinical practice guidelines 1.
From the Research
Hypocalcemia Workup
- Hypocalcemia can be caused by various disorders, including hypoparathyroidism, vitamin D deficiency, and chronic kidney disease 2, 3, 4, 5
- Symptoms of hypocalcemia can range from asymptomatic to life-threatening conditions, including neuromuscular irritability, tetany, and seizures 2, 4
- The workup for hypocalcemia typically involves measuring serum calcium levels, as well as parathyroid hormone (PTH) and vitamin D levels 2, 3, 4
Diagnostic Approach
- The diagnostic approach to hypocalcemia involves identifying the underlying cause, which can be divided into PTH-mediated and non-PTH mediated disorders 4
- In PTH-mediated disorders, such as hypoparathyroidism, the goal is to replace the missing hormone and maintain serum calcium levels in the low-normal range 2, 4
- In non-PTH mediated disorders, such as vitamin D deficiency, the goal is to replace the deficient vitamin and maintain serum calcium levels 3, 4
Treatment Options
- Treatment options for hypocalcemia depend on the underlying cause and severity of the condition 2, 3, 4
- Intravenous calcium infusion is essential for acute hypocalcemia, while oral calcium and/or vitamin D supplementation is used for chronic hypocalcemia 2, 3, 4
- Recombinant human PTH (rhPTH) has been approved for the treatment of hypoparathyroidism, which can help reduce the daily requirements of calcium and active vitamin D supplements 4