Different Varieties of Sample Collection Tubes for Laboratory Use

Types of Sample Tubes An Overview

In the world of laboratory medicine, sample tubes play a crucial role in the collection, transportation, and analysis of biological samples. Different types of sample tubes are designed to cater to specific tests and ensure the integrity of samples. This article will explore the various types of sample tubes, their materials, additives, and applications in medical diagnostics.

1. Types of Sample Tubes

Sample tubes can be broadly categorized based on their purpose and the materials used. The main types of tubes include

- Serum Separator Tubes (SST) These tubes are used to collect blood samples for serum testing. They typically contain a gel that separates serum from blood cells after centrifugation. SSTs are commonly used for a variety of biochemical assays.

- Plasma Separator Tubes (PST) PSTs contain an anticoagulant, such as lithium heparin, and a gel to separate plasma from blood cells. They are useful for tests requiring plasma samples, such as certain electrolyte and hormone tests.

- EDTA Tubes These purple top tubes contain ethylenediaminetetraacetic acid (EDTA), an anticoagulant that prevents blood clotting. EDTA tubes are commonly used for complete blood counts (CBC) and other hematological tests.

- Citrate Tubes Blue top tubes contain sodium citrate, which also acts as an anticoagulant. Citrate tubes are primarily used for coagulation tests, such as prothrombin time (PT) and activated partial thromboplastin time (aPTT).

- Fluoride Tubes Gray top tubes contain sodium fluoride and potassium oxalate. Sodium fluoride acts as a glycolysis inhibitor, making these tubes suitable for glucose testing and lactate analysis.

2. Materials Used

Sample tubes are typically made from either glass or plastic. Glass tubes are preferred for certain applications due to their chemical resistance and the ability to withstand sterilization. However, plastic tubes are lighter, less prone to breakage, and generally more cost-effective. The choice between glass and plastic often depends on laboratory protocols and the specific tests being performed.

3. Additives and Their Functions

Different sample tubes contain specific additives to facilitate certain laboratory procedures

- Anticoagulants These are substances that prevent blood from clotting. They are essential for tests that require plasma or whole blood, as they help maintain the fluid state of the sample.

- Separating Gels These gels are used in SSTs and PSTs to provide a physical barrier between serum/plasma and the cellular components after centrifugation, ensuring cleaner samples for testing.

- Inhibitors Certain additives, like sodium fluoride, inhibit enzymatic activity to preserve specific analytes, making them crucial for accurate results in tests like glucose measurement.

4. Choosing the Right Tube

Choosing the appropriate sample tube is vital for ensuring accurate test results. Factors to consider include the type of sample being collected (whole blood, serum, or plasma), the required tests, and the specific laboratory protocols in place. Proper labeling and storage conditions are also essential to maintain sample integrity.

Conclusion

In summary, the selection of sample tubes is fundamental in the field of laboratory diagnostics. Understanding the various types of tubes, their materials, and additives helps healthcare professionals collect and process samples effectively. The right choice of sample tube not only ensures the accuracy of test results but also contributes to better patient outcomes. As technology and research advance, innovations in sample tube design may continue to enhance their functionality and reliability in the clinical setting.