Blood Sample Testing

Captiva Lab offers a wide array of blood tests that can fit your testing needs. From general chemistry, to viral immunology, to tumor markers, to endocrinology, to hematology our instruments are top of the line and guaranteed to produce accurate results. Utilizing state-of-the-art instruments like the Abbott Architect ci8200 which eliminates biotin interference in results of laboratory tests that use the biotin-streptavidin capture method. The Architect is the only platform on the market today that is 100% free from biotin interference. We strive to deliver the most precise results with a prompt turnaround time. Other top of the line instruments in facilities include instruments from Sysmex, the market leader in CBC testing, and Siemens. Have faith in the results you provide your clients and send your blood samples to Captiva for testing.

About Diagnostic Blood Testing

Diagnostic lab testing has long utilized blood samples as one of the most reliable methods for detecting abnormalities in clients. The blood sample itself can be several different specimen types; Serum, Plasma, or Whole blood. Certain diagnostic tests require a certain sample type as certain methods will remove elements from the blood.

What is a Whole Blood Sample?

‘Whole Blood’ is simply, blood collected straight from the donor. This is the most basic type of collection, and what is used for donation purposes. It can be mixed with several preservatives or anticoagulants as needed prior to testing.

What is a Blood Serum Sample?

For the purposes of diagnostic testing, a ‘blood serum sample’ is a blood sample that has been centrifuged after it has been allowed to clot. After collection from a patient, it is not mixed with an anti-clotting agent. Some serum tubes utilize a gel that aides in the separation process. This step generally takes about 30 minutes. After blood has clotted it is then centrifuged.  This separates the the clotting material, the liquid component is ‘blood serum’.

What is a Plasma Sample?

A ‘plasma’ sample is blood that has been collected and not allowed to clot. It is often mixed with an anticoagulant when collected, then it is centrifuged. Plasma retains fibrinogen, a clotting component, unlike ‘blood serum’. The centrifuging separates the blood cells, which fall to the bottom of the tube. The top liquid component (plasma) is transferred into a new tube. This liquid now lacks the white and red blood cells found in the other sample types. There are more coagulation factors that affect the clotting process, depending on the test it may be necessary to use other anticoagulants to interfere with their activity.

Types of blood samples

Components of the Blood

Blood (or whole blood) drawn straight from the body contains several components.

  • Red blood cells (RBCs)carry oxygen from the lungs throughout the body. When depleted they carry carbon dioxide back to the lungs for removal and repeat the process. Red blood cells have a protein called ‘hemoglobin’ inside of them that carry oxygen. They are created inside bones and live for about 120 days. The most common type of issues with red blood cells are anemia. RBCs make up 40-45% of the whole blood.
  • White blood cells (WBCs) are known for fighting infections in the body. Also known as leukocytes, they attack infectious diseases and foreign substances. They are created in the bone marrow and are different from RBCs in that they have a nuclei. WBCs can be broken down into many types, each with a different function. The measurement of white blood cell count is extremely important as it can indicate the presence of a disease. White blood only makes up about 1% of the whole blood but provides an extremely important insight into health and immunity.
  • Platelets are a coagulant within the blood. Also known as thrombocytes, they lack structure and are fragments of cytoplasm. They are about 1/5th the size of a red blood cell. Their main function is to stop bleeding.
  • Plasma is a yellowish liquid in which the other elements pass through. It carries nutrients, hormones and proteins throughout the body. It makes up about 55% of the whole blood content. It is 95% water.

Invalidating Blood Samples

There are several ways a blood sample can be invalidated. Mishandling specimens results in unacceptable samples for quality testing.


Serum that has turned dark or bright yellow, rather than its straw yellow color may indicate poor sample quality, but may also be a sign of too much bilirubin in the patient (jaundice). This can be caused by red blood cell breakdown, either a failure of the collection process, or indicative of jaundice.

Turbidity (Lipemia)

Serum that has turned milky or turbid may indicate several things invalidating a test. The patient recently eating a meal may produce transient lipemia. The turbid sample may also indicate bacterial infection.

Radioisotope Interference

If the patient has been administered isotopes, it may interfere with certain assays. Specimens should be obtained before administering isotopes.


When serum or plasma are separated, the delicate walls of red blood cells can be disrupted and other components may escape into the liquid sample. This typically changes the, ideally, straw yellow sample, to something with a more pink or red hue. Samples with hemolysis may be rejected as they alter the results of certain assays.

Types of cells in blood



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