From the Guidelines
Low serum calcium, or hypocalcemia, requires prompt treatment based on severity and symptoms, with a focus on maintaining normal serum calcium levels to prevent secondary hyperparathyroidism and renal osteodystrophy, as suggested by the 2018 Kidney Disease: Improving Global Outcomes clinical practice guideline update 1. For mild cases (8.0-8.5 mg/dL), oral calcium supplements like calcium carbonate 1000-2000 mg daily divided into 2-3 doses are recommended, preferably taken with food.
- The dose and frequency of calcium supplements may need to be adjusted based on individual patient needs and response to treatment.
- Vitamin D supplementation (ergocalciferol 50,000 IU weekly or cholecalciferol 1000-2000 IU daily) should accompany calcium therapy to enhance intestinal calcium absorption, as supported by the 2003 K/DOQI clinical practice guidelines for bone metabolism and disease in chronic kidney disease 1. For moderate to severe hypocalcemia or if symptoms like muscle cramps, numbness, or tetany are present, intravenous calcium gluconate 1-2 grams over 10-20 minutes may be necessary, followed by a continuous infusion in critical cases.
- Identifying and treating the underlying cause of hypocalcemia is crucial, whether it's vitamin D deficiency, hypoparathyroidism, chronic kidney disease, or medication effects.
- Regular monitoring of serum calcium, phosphate, and vitamin D levels is essential to adjust treatment and prevent potential complications, such as secondary hyperparathyroidism and renal osteodystrophy. Hypocalcemia can be dangerous if severe, potentially causing seizures, cardiac arrhythmias, or laryngospasm, so maintaining adequate calcium levels is vital for proper nerve, muscle, and cardiac function, as highlighted by the association between higher calcium concentrations and increased mortality in adults with CKD 1.
From the Research
Definition and Causes of Low Serum Calcium
- Low serum calcium, also known as hypocalcemia, is a condition where the calcium level in the blood is lower than normal 2, 3, 4, 5.
- It can be caused by various disorders, including hypoparathyroidism, vitamin D deficiency, and excessive phosphate intake 2, 3, 5.
- Hypoparathyroidism is a condition where the parathyroid gland does not produce enough parathyroid hormone (PTH), leading to low calcium levels in the blood 2, 3.
Symptoms and Diagnosis of Low Serum Calcium
- Symptoms of hypocalcemia can range from mild to severe and include neuromuscular irritability, tetany, seizures, and malignant arrhythmias 2, 3, 4, 5.
- Diagnosis is typically made by measuring the calcium level in the blood, and may also involve other tests such as PTH and vitamin D levels 2, 3, 4, 5.
- In newborns and infants, hypocalcemia is defined as a total serum calcium level below 8 mg/dL (2 mmol/L) or ionized calcium level below 4.4 mg/dL (1.1 mmol/L) 5.
Treatment and Management of Low Serum Calcium
- Treatment of hypocalcemia depends on the underlying cause and severity of the condition 2, 3, 4, 5.
- Acute hypocalcemia is typically treated with intravenous calcium infusion, while chronic hypocalcemia may be managed with oral calcium and vitamin D supplementation 2, 3, 4.
- In cases of hypoparathyroidism, recombinant human PTH (rhPTH) may be used to replace the missing hormone and help regulate calcium levels 3.
- In newborns and infants, treatment of hypocalcemia typically involves calcium replacement, with elementary calcium replacement of 40 to 80 mg/kg/d recommended for asymptomatic newborns 5.