Magnesium RBC blood test is used to measure the level of magnesium found in the red blood cells floating in the blood serum. The test is usually only ordered when there is reason to believe that an individual might have a magnesium deficiency. Symptoms of low levels of magnesium in the red blood cells include cardiac arrhythmias, seizures, and muscle cramping and weakness.
The RBC blood test is more sensitive to magnesium deficiencies than a standard magnesium blood test. When the body becomes magnesium deficient, it pulls the magnesium that is stored in red blood cells out of those cells and into the serum of the blood. A standard blood test, therefore, may show magnesium levels as normal even though the red blood cell’s stores of magnesium are depleted. Magnesium is crucially important for bone and muscle health. Early detection and treatment of a magnesium deficiency helps to prevent the development of more chronic problems.
Ionized calcium test, or calcium ionized serum test, is occasionally useful when hypercalcemia coexists with an abnormal protein state like myeloma. When calcium is low, this blood test can be helpful in assessing active calcium fraction in hypoproteinemia and acidosis. Calcium in serum exists ionized, bound to organic anions such as phosphate and citrate, and bound to proteins, mainly albumin. Of these, ionized calcium is the physiologically important form. By measuring the serum ionized calcium, insight into the effect of total protein and albumin on serum calcium levels can be obtained. A patient can have high total calcium, with normal ionized calcium and increased total protein and/or albumin, as in dehydration or in myeloma. Women have greater circadian variation of ionized calcium and intact PTH than men. There is typically an inverse relationship between ionized calcium and phosphate concentration.
The Vitamin D 25-Hydroxy Blood Test is often ordered for individuals that have symptoms of vitamin D deficiency. It may also be ordered before an individual begins osteoporosis drug therapy. Low levels may indicate a dietary deficiency, malabsorption or lack of exposure to sunlight.
Vitamin D 1,25-dihydroxy is the active form of vitamin D. The body converts the relatively inactive form, 25-hydroxyvitamin D, to 1,25-dihydroxyvitamin D. The Vitamin D 1,25 Dihydroxy Blood Test measures levels of the active hormone form of vitamin D in the blood, which may be necessary if a condition that produces excess vitamin D is suspected. Such diseases include sarcoidosis and some forms of lymphoma. High levels can be indicative of such conditions, or of excess parathyroid hormone.