Questions and Answers
What is the primary function of the corrected calcium test?
What is the purpose of measuring urine calcium levels?
Which of the following hormones helps regulate calcium levels in the blood?
What is the primary reason for requesting a calcium test?
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What type of calcium test measures the calcium that is unattached from certain proteins in the blood?
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Why is albumin concentration important when measuring calcium levels?
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A patient presents with symptoms of excessive thirst and frequent urination. Which of the following tests would be most appropriate to order?
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Which of the following conditions can cause a low blood calcium level?
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What is the preferred specimen for a calcium test?
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What is the recommended storage temperature for serum calcium samples for a period of 10 days?
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What is the normal blood calcium level for adults?
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A patient with a serum albumin level of 3.5 g/dL has a serum calcium level of 9.0 mg/dL. What is the corrected calcium level?
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What is the most likely cause of hypercalcemia?
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Which of the following conditions can cause hypocalcemia?
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Study Notes
Importance of Calcium
- Calcium is essential for muscle, nerve, and heart function, as well as blood clotting and bone and teeth formation.
Types of Calcium Blood Tests
- Total calcium: measures calcium attached to proteins in blood and "free" calcium
- Ionized calcium: measures "free" calcium, unattached to proteins
- Corrected calcium: adjusts total calcium for albumin concentration to reflect "ionized" levels
Regulation of Calcium in the Blood
- Parathyroid hormone (PTH)
- 1, 25-dihydroxyvitamin D (Vitamin D)
- Calcitonin
When is Calcium Testing Requested?
- Kidney stones, bone disease, or neurologic disorders
- Kidney disease, thyroid disease, intestinal disease, cancer, or poor nutrition
- Symptoms of excessive or low calcium levels
Sample Collection and Preparation
- Fresh serum collected in the fasting state
- Serum or plasma should be separated from blood cells quickly to prevent altered calcium values
- Calcium in serum is stable for 7 days at room temperature, 10 days refrigerated, and 1 month frozen
Calcium Determination Procedure
- Colorimetric methods used for calcium determination
- Mix, incubate, and measure absorbance of specimen and standard against reagent blank
Expected Value
- Normal blood calcium level for adults: 8.5-10.2 milligrams/deciliter
- Corrected calcium formula: serum calcium + 0.8 * (4 - serum albumin)
Interpretation of Results
- Hypercalcemia: hyperparathyroidism, cancer, hyperthyroidism, tuberculosis, acute kidney injury, excess Vitamin D intake
- Hypocalcemia: hypoparathyroidism, vitamin D deficiency, kidney failure, hypomagnesemia, pancreatitis, celiac disease, or malabsorption
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Description
This quiz covers the scenarios in which a doctor may request a calcium test, including kidney disease, symptoms of excessive or low calcium, and various medical conditions.
