From the Guidelines
Hypocalcemia is primarily caused by insufficient calcium levels in the blood, which can result from various factors, including vitamin D deficiency, hypoparathyroidism, kidney dysfunction, magnesium deficiency, and certain medications, as supported by recent studies 1.
Causes of Hypocalcemia
The causes of hypocalcemia can be multifactorial and include:
- Vitamin D deficiency: The most common cause, as vitamin D is essential for calcium absorption.
- Hypoparathyroidism: Inadequate production of parathyroid hormone (PTH) impairs calcium regulation, as seen in patients with 22q11.2 deletion syndrome 1.
- Kidney dysfunction: Impaired vitamin D activation and calcium reabsorption, as observed in chronic kidney disease patients 1.
- Magnesium deficiency: Magnesium is necessary for proper PTH function.
- Certain medications: Some drugs like bisphosphonates or certain chemotherapies can lower calcium levels.
- Pancreatitis: Can cause calcium to bind with free fatty acids.
- Malabsorption disorders: Conditions like celiac disease or inflammatory bowel disease can impair calcium absorption.
- Rapid blood transfusions: The citrate in stored blood can bind calcium.
- Severe acute illness: Can cause a shift of calcium into cells.
- Hereditary disorders: Some genetic conditions affect calcium metabolism, such as 22q11.2 deletion syndrome 1.
Management of Hypocalcemia
To address hypocalcemia, treatment typically involves correcting the underlying cause and supplementing calcium. In severe cases, intravenous calcium gluconate may be necessary. Long-term management often includes oral calcium supplements (1000-1500 mg/day) and vitamin D (800-1000 IU/day), as recommended for adults with 22q11.2 deletion syndrome 1. Regular monitoring of serum calcium, phosphate, and vitamin D levels is crucial for effective management. Additionally, targeted monitoring of calcium concentrations should be considered at vulnerable times, such as peri-operatively, perinatally, or during severe illness 1.
From the Research
Causes of Hypocalcemia
- Hypocalcemia can be caused by multiple disorders, including hypoparathyroidism, which is characterized by impaired secretion of parathyroid hormone (PTH) 2
- Disorders that disrupt the metabolism of vitamin D can also lead to chronic hypocalcemia, as vitamin D is responsible for increasing the gut absorption of dietary calcium 2, 3
- Vitamin D deficiency is a common cause of hypocalcemia, and can be due to unbalanced diets, inadequate exposure to sunlight, or other factors 3, 4
- Certain medications, such as phenytoin, can also induce hypocalcemia, particularly in patients with concomitant vitamin D deficiency 5
- Other causes of hypocalcemia include chronic renal failure, deposition of calcium in bone or soft tissues, and loss of calcium into urine 6
Underlying Mechanisms
- Parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D play a crucial role in maintaining calcium homeostasis, and disorders that affect these hormones can lead to hypocalcemia 2, 6
- Vitamin D deficiency can lead to decreased gut absorption of dietary calcium, resulting in hypocalcemia 3, 4
- Phenytoin-induced hypocalcemia is thought to be due to the drug's effect on vitamin D metabolism and calcium absorption 5