Emergency Central is a collection of disease, drug, and test information including 5-Minute Emergency Medicine Consult, Davis’s Drug, McGraw-Hill Medical’s Diagnosaurus®, Pocket Guide to Diagnostic Tests, and MEDLINE Journals created for emergency medicine professionals. Explore these free sample topics:
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- Hypocalcemia is defined as a total plasma calcium level <8.7 mg/dL:
- Ionized calcium may be normal and, therefore, have no clinical manifestations.
- Normal total serum calcium concentrations are 8.7–10.5 mg/dL.
- Incidence in the general population is 0.6%.
- From either increased loss of calcium from the circulation or decreased entry into the circulation
- Intravascular calcium circulates in 3 forms:
- Bound to proteins (mainly albumin): 45–50%
- Bound to complexing ions (citrate, phosphate, carbonate): 5–10%
- Ionized (free) calcium (physiologically active form): 45–50%
- Serum levels of calcium are primarily controlled by 3 hormones:
- Parathyroid hormone (PTH)
- Decrease in calcium levels leads to an increase in PTH secretion (increasing bone resorption, renal absorption, intestinal absorption, urinary phosphate excretion).
- Vitamin D (1,25-dihydroxyvitamin D):
- Decrease in calcium level activates vitamin D (increasing bone resorption and intestinal absorption).
- Causes a direct inhibition of bone resorption with increased calcium levels
- Hypoalbuminemia—the most common cause:
- Each 1 g/dL decrease in serum albumin decreases protein-bound serum calcium by 0.8 mg/dL.
- Ionized (free) calcium levels do not change.
- Children have higher values of normal calcium (9.2–11 mg/dL).
- Neonatal hypocalcemia: Total serum calcium concentrations <7.5 mg/dL or serum-ionized calcium levels <4 mg/dL
- Symptoms of hypocalcemia in infancy:
- Hyperactivity, jitteriness
- Apneic spells with cyanosis