Toxicology: Mineral testing

Three-dimensional, colorful, periodic table.

By Chelsea Sykes, Diagnostic Toxicologist, WADDL

Mineral Round-Up

Mineral testing is very beneficial in keeping productivity high and animals healthy. However, minerals are also very complicated and trying to efficiently and effectively sample herds can feel like navigating a labyrinth. Here are some tips and tricks to try to simplify sampling for minerals.

  1. More is better for herd sampling. This is true for sample volume and total number of samples. We recommend testing 1 in 10 for herds larger than 30-50 head, and either 1 in 4 or 1 in 5 for herds <30 head.
  2. Liver is best in most cases. If liver isn’t an option, the most optimal sample will depend on the mineral you are most interested in. If liver biopsies are an option, they should be placed in a cassette or an empty tube (no additives). You may need two biopsies to achieve an adequate sample mass!
  3. Check with the specific lab for guidelines! WADDL offers specific recommendations for mineral testing, but other labs might differ in recommendations. You can start with our Submit a sample page for general information and will find specific guidance for given test on our Toxicology Test site. For example, if you select Tissue Mineral Screen you will find information related to the mineral options, specimens required (liver or kidney), sampling requirements including collection containers and packing instructions.
  4. Separate serum from the clot before mailing in the samples. Many mineral concentrations will change (mostly increasing but a few will decrease) if hemolysis occurs or red blood cells are not removed quickly. Ideally, any serum samples should be separated from the clot within 30 minutes of collection and 10 minutes of clotting and put into a new tube without additives. Gel separators within tubes often shift during transport and cause contamination of samples.

When liver isn’t an option

  1. Selenium, Lead, Arsenic: whole unclotted blood = Lavender Top Tube (or purple top tube). These minerals are part of the red blood cells so the RBCs are needed for optimal testing. EDTA preservation is preferred. Can also utilize heparinized blood or sodium citrate blood.
  2. Copper, Zinc, Iron: serum = Royal Blue Top Tube (no additive). Serum should be separated from the clot and placed in another Royal Blue top tube (no additive) or in a white top tube (no additive) within 30 minutes of collection.
    1. Zinc is especially challenging as rubber in blood tubes can leach zinc into the sample causing false elevations. Avoid rubber if possible!
    1. Copper is the most stable with regard to hemolysis and RBC exposure and is tightly controlled by the body so mild deficiencies can be missed with serum testing.
  3. Magnesium: serum and urine = any tube will work for these. Separate serum before submission. Magnesium fluctuates throughout the day in most mammals. Interpretation requires comparison between urine and serum magnesium concentrations that have been corrected with creatinine concentrations.
  4. Vitamin E: serum = Red Top Tube or Royal Blue Top Tube (no additive). Separate serum from the clot and place in new blood tube before submission and protect from light! Put the serum tube in a glove or wrap with aluminum foil. Vitamin E is not a mineral but is very important and we often see problems with Vitamin E AND Selenium.