The Test Sample
What is being tested?
Trace mineral tests measure the concentration of specific minerals in a sample of blood, urine, or other body fluid or tissue. These minerals are substances that the body needs in minute amounts on a regular basis for normal functioning. They are absorbed from the diet and are used in the production of enzymes and hormones, in the regulation of glucose, and in the formation of bone, teeth, muscles, connective tissue, and blood cells. The minerals assist in the metabolism of proteins, fats, and carbohydrates, promote wound healing, and are vital for the transport of oxygen throughout the body.
Trace minerals are a subset of micronutrients and essential minerals. They include:
- Fluoride (usually included but rarely tested)
Trace mineral deficiencies may occur as a result of insufficient food, insufficient variety of food, and/or mineral deficiencies in the soil where food is grown. The World Health Organization lists iodine, iron, and vitamin A as the most important micronutrients in terms of global public health. In the United States, deficiencies and excesses of trace minerals are less common, although iron deficiency remains a significant problem. Deficiencies may occur with:
- Insufficient intake – such as from malnutrition or a restricted diet. Sometimes seen when someone receives only intravenous nutrition.
- Insufficient absorption – may be seen with a variety of chronic conditions, such as celiac disease, associated with malabsorption or with surgeries that remove part of the stomach or intestines.
- Inability to use – some people may not be able to properly utilize one or more trace minerals.
- Increased use/need – pregnant women, children, and those recovering from an illness or injury may require increased nutritional support.
- Increased loss – an example is the loss of iron that occurs when red blood cells are lost due to acute or chronic bleeding.
- Interference – an example is the decrease in copper often associated with an excess of zinc.
Trace mineral excesses may be seen with:
- Too much intake – this may be chronic or acute, due to taking supplements or to accidental or occupational exposure.
- Decreased loss – with conditions such as kidney and liver disease, the body may not be able to remove trace minerals at a normal rate. With some inherited conditions, the body may store minerals in tissues and organs, which can cause damage. An example includes the overabundance of copper storage seen in Wilson disease.
How is the sample collected for testing?
Trace mineral testing is usually performed on a blood sample obtained by inserting a needle into a vein in the arm. Sometimes a 24-hour urine collection is obtained. Special metal-free blood or acid-washed urine containers are used to minimize the potential for sample contamination by any outside sources of minerals.
Blood and urine samples best reflect recent mineral intake. Rarely, hair may be collected or a biopsy may be performed to obtain a tissue sample to evaluate mineral deficiencies, excesses, and storage that have occurred over time.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
Talk to your health care practitioner; fasting is preferred for some tests.