Calcium Ionized Serum Test

What is Ionized Calcium?

Calcium is one of the most essential minerals found in the body. Calcium helps the body to sustain healthy bones and teeth. In addition, calcium also plays a part in ensuring that the heart, muscles, and nerves are functioning correctly. The majority of the calcium in the body is located in the bones, while the remainder circulates in the blood. Approximately half of the calcium circulating in the blood is “free” and not attached to proteins. This form of calcium is known as ionized calcium or free calcium. The remaining half is “bound” to proteins, such as albumin and globulins, with a smaller amount fused to anions like phosphate. 

What is the purpose of this test?

Order this Calcium Ionized Serum Test to measure ionized calcium levels in the blood to help screen for, diagnose, and monitor various conditions related to the bones, heart, nerves, kidneys, and teeth. For example, in some people, the balance between free (ionized) and bound calcium is disturbed, and a total calcium test may not reflect the overall calcium status. In these cases, the measurement of ionized calcium may be necessary.

This test may be helpful for individuals with the following health conditions:

• Critically ill
• Receiving blood transfusions or intravenous fluids
• Undergoing major surgery 
• Abnormal blood protein (low albumin)

What causes abnormal ionized calcium levels?

Several health conditions may cause abnormal ionized calcium levels. Higher than average ionized calcium levels may be caused by the following:

• Bed rest for an extended period
• Hyperparathyroidism
• Hyperthyroidism
• Consuming too much vitamin D or calcium
• Certain cancers, multiple myeloma, and T-cell lymphoma
• Metastatic bone tumor
• Infections causing granulomas such as tuberculosis, fungal and mycobacterial infections
• Paget disease
• Sarcoidosis
• Tumors that produce a parathyroid hormone-like substance
• Taking medications such as lithium, tamoxifen, and thiazides

Additionally, lower-than-average ionized calcium levels may be due to the following:

• Intestinal absorption issues
• Kidney failure
• Liver disease
• Hypoparathyroidism
• Deficiencies of albumin, magnesium, or vitamin D
• Pancreatitis

When should I order a Calcium Ionized Serum Test?

Individuals may order this Calcium Ionized Serum Test if they have experienced symptoms related to abnormal ionized calcium levels in the blood. For example, individuals with abnormal ionized calcium levels may experience the following symptoms:

• Increased thirst
• Frequent urination
• Mental changes, such as fatigue or confusion
• Bone pain
• Muscle twitching
• Muscle weakness
• Digestive upset, including nausea, appetite loss, and constipation
• Muscle cramps
• Dry skin
• Brittle fingernails
• Tingling in the lips, fingers, or feet
• Seizures
• Abnormal heart rhythm