Quick facts
Low calcium shows up in the nerves and muscles
- Hypocalcemia causes numbness and tingling of the lips, tongue, hands, and feet, muscle cramps, and tetany. Hypoparathyroidism, vitamin D deficiency, and kidney disease can cause it, and a high phosphorus level from kidney failure can push calcium down.[2]
- Chvostek's sign is twitching of the facial muscles when the facial nerve is tapped. Trousseau's sign is a hand spasm when a blood pressure cuff stays inflated above the systolic pressure for three minutes. Both are classic signs of acute hypocalcemia.[2]
High calcium brings constipation and weakness, and raises the risk of digoxin toxicity
Total calcium and ionized calcium are different tests
- About half of blood calcium is bound to proteins and the rest is free, or ionized. The usual test measures total calcium. An ionized calcium test is usually ordered when the total is abnormal, or when the patient is seriously ill or having surgery.[5]
- Because total calcium includes the calcium bound to blood proteins, a low blood protein level, from liver disease or malnutrition, can lower the total calcium result.[5]
Calcium is one of the eight tests in the Basic metabolic panel flashcard deck. Find the deck in the free app preview.
Open the free app previewHow it shows up on nursing exams
Practice question
A nurse reviews morning total calcium results for four adult patients. The laboratory reference range is 8.8 to 10.2 mg/dL. Which patient's result should the nurse report to the health care provider first?
- A. Bed rest for two weeks: calcium 10.1 mg/dL, mild constipation, no other symptoms
- B. Atrial fibrillation, taking digoxin: calcium 9.6 mg/dL, apical pulse 78
- C. Kidney failure: calcium 7.9 mg/dL, lip tingling, hand spasm with cuff inflated
- D. Vitamin D deficiency: calcium 8.9 mg/dL, no tingling or cramps
Show the answer and why
Correct answer: C. Kidney failure: calcium 7.9 mg/dL, lip tingling, hand spasm with cuff inflated
- A. Incorrect. Prolonged immobility can raise calcium, but 10.1 mg/dL is still inside the 8.8 to 10.2 range. It is worth watching, not the first report.
- B. Incorrect. High calcium can increase the risk of digoxin toxicity, but 9.6 mg/dL is mid-range.
- C. Correct. 7.9 mg/dL is below 8.8, and tingling with a hand spasm while the cuff stays inflated (Trousseau's sign) are signs of acute hypocalcemia. Kidney failure can raise phosphorus and push calcium down. This is the result to report first.
- D. Incorrect. Vitamin D deficiency can cause hypocalcemia, but 8.9 mg/dL is inside the range and the patient has no tingling or cramps.
Sources for this question: [1][2][4]
Memory hook: Low calcium: tingling, twitching, and cramps. High calcium: constipation and muscle weakness.