The main difference between ionized calcium and serum calcium is that ionized calcium is the amount of free calcium in the blood whereas serum calcium is the total amount of calcium present in the blood. Furthermore, ionized calcium is the most active form of calcium in the blood while serum calcium includes calcium bound to anions and proteins and free calcium amount in the blood.
Ionized calcium and serum calcium are two types of measurements of calcium in the blood. Also, calcium bound to anions and calcium bound to proteins are the other tests that measure calcium amounts in the blood.
Key Areas Covered
1. What is Ionized Calcium
– Definition, Reference Levels, Importance
2. What is Serum Calcium
– Definition, Reference Levels, Importance
3. What are the Similarities Between Ionized Calcium and Serum Calcium
– Outline of Common Features
4. What is the Difference Between Ionized and Serum Calcium
– Comparison of Key Differences
Key Terms
Calcium Amounts in Blood, Hypercalcemia, Ionized Calcium, Serum Calcium, Thyroid Disease
What is Ionized Calcium
The ionized calcium is the amount of calcium freely available in the blood. In other words, these calcium ions are not bound to any anion or protein in the serum. Therefore, ionized calcium is the most effective form of calcium which is readily available for cells. Generally, calcium is the cation responsible for the strength of bones and teeth. Also, it helps the functioning of muscles and nerves.
Figure 1: Calcium Regulation
Since ionized calcium is the free calcium in the blood, measuring the amount of ionized calcium is crucial when an individual shows the signs of kidney disease, certain cancers, and abnormal functioning of the parathyroid gland. Also, the unbalanced ratio between free and bound calcium may indicate abnormal levels of serum proteins such as albumin or immunoglobulins. Typically, the ionized calcium has to be half of the serum calcium in the blood.
What is Serum Calcium
Serum calcium is the total amount of calcium in the blood. Moreover, calcium ions occur in the blood in three forms. They can be bound to the serum proteins like albumin or other anions in the blood. The other calcium ions occur freely in the blood. Serum calcium includes all three types of calcium ions in the blood. This test is important to diagnose kidney disease, cancer, parathyroid disease, and malnutrition.
Figure 2: Brown Tumors Resulted by Hypercalcemia in Bones
Moreover, the higher levels of serum calcium indicate hypercalcemia. Some of the symptoms of hyperthyroidism are the tiredness, low appetite, nausea or vomiting, frequent urination, pain, constipation, and excessive thirst. On the other hand, the lower levels of serum calcium indicate hypocalcemia whose major symptoms are muscle cramps, cramps in the abdomen, the tingling sensation in your fingers, and irregular heartbeat.
Similarities Between Ionized Calcium and Serum Calcium
- Ionized calcium and serum calcium are two main types of tests which measure the amount of calcium in the blood.
- These measurements are important to diagnose a number of disease conditions including hypo and hyperparathyroidism, calcium malabsorption, vitamin D deficiency, kidney failure, etc.
Difference Between Ionized Calcium and Serum Calcium
Definition
Ionized calcium refers to calcium in the blood that is not attached to proteins while serum calcium refers to the total amount of calcium in your blood. Thus, this is the main difference between ionized calcium and serum calcium.
Significance
Furthermore, ionized calcium is the most active form of calcium in the blood while serum calcium includes both free and calcium bound to anions and serum proteins.
Performing the Test
Another difference between ionized calcium and serum calcium is that ionized calcium test requires special handling of blood samples and it is rare while serum calcium test is easy to perform and it is common.
Reference Range
The normal level of ionized calcium is 4.64 to 5.28 mg/dL in adults while the normal level of serum calcium is 8.6 and 10 mg/dL.
Lower Levels
Lower levels of ionized calcium may indicate hypoparathyroidism while lower levels of serum calcium may indicate hypocalcemia. This is another difference between ionized calcium and serum calcium.
Higher Levels
Higher levels of calcium is another difference between ionized calcium and serum calcium. Higher levels of ionized calcium may indicate hyperparathyroidism while lower levels of serum calcium may indicate hypercalcemia.
Conclusion
Ionized calcium is the amount of calcium freely available in the blood. Some of the calcium in the blood may bind to anions and proteins. Therefore, they are not readily available. In comparison, serum calcium includes both free and bound calcium in the blood. The main difference between ionized calcium and serum calcium is the form of calcium measured in each test. Both tests are important to diagnose various types of disease conditions.
References:
1. Murrell, Daniel. “Ionized Calcium Test: Purpose, Procedure & Risks.” Healthline, Healthline Media, Available Here
2. Sampson, Stacy. “Calcium Blood Test: Normal Range, High, Low.” Healthline, Healthline Media, Available Here
Image Courtesy:
1. “Calcium regulation” By Mikael Häggström (Public Domain) via Commons Wikimedia
2. “Bone hypercalcemia – intermed mag” By Nephron – Own work (CC BY 3.0) via Commons Wikimedia
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