| Lithium Heparin Tube | Green | Heparinized plasma | Routine plasma chemistry, electrolytes, renal function, liver function, cardiac markers, therapeutic drug monitoring, and many urgent chemistry tests | Rapid plasma separation; suitable for many chemistry analyzers; lithium heparin generally has less impact on sodium measurement than sodium heparin | Fill to the stated volume and gently invert approximately 8–10 times immediately after collection. Centrifuge according to the laboratory’s validated time and speed. | Not suitable for tests in which heparin or lithium may interfere. Do not use for coagulation studies unless specifically validated by the laboratory. |
| Lithium Heparin Plasma Separator Tube | Light green | Plasma separated by a gel barrier | Routine and urgent plasma chemistry, electrolytes, metabolic panels, liver enzymes, and selected immunochemistry tests validated for this tube type | Gel barrier helps separate plasma from cells and can support efficient workflow and transport | Invert gently approximately 8–10 times. Allow the tube to clot-free process as specified by the manufacturer; centrifuge only after the required equilibration period and within validated limits. | Gel-related interference or adsorption may affect selected analytes, drugs, hormones, or specialized assays. Confirm compatibility before use. |
| Sodium Heparin Tube | Dark green | Heparinized plasma or whole blood, depending on the test | Selected plasma chemistry, specialized chemistry, some cytogenetic procedures, and tests requiring sodium rather than lithium as the heparin salt | Provides heparin anticoagulation without adding lithium to the specimen | Mix immediately with approximately 8–10 gentle inversions. Use only the additive and specimen type specified in the test procedure. | Added sodium can affect sodium-related measurements. It may not be interchangeable with lithium heparin for every chemistry method. |
| Sodium Heparin Tube for Trace-Element Testing | Royal blue or laboratory-specified color | Low-contamination heparinized plasma or whole blood | Selected trace-element and metal assays when the laboratory method specifically requires a heparinized specimen | Manufactured and handled to reduce contamination from tube materials and collection equipment | Use only certified low-contamination tubes and collection devices. Follow strict contamination-control procedures, including clean collection areas and validated transport conditions. | Cap colors and additive configurations vary. A standard green tube should not be substituted for a trace-element tube without laboratory approval. |
| Lithium Heparin Tube for Blood Gas or Critical-Care Testing | Usually balanced heparin in a syringe or dedicated blood-gas device | Heparinized whole blood | Blood gases, pH, oxygen, carbon dioxide, ionized calcium, lactate, and selected point-of-care measurements | Preserves a whole-blood specimen for rapid analysis and supports measurement of gases and selected electrolytes | Use balanced, dry heparin when required. Remove air bubbles promptly, mix thoroughly, keep the specimen within the validated temperature and time limits, and analyze as soon as possible. | Excess liquid heparin can dilute the specimen and alter electrolytes, pH, and blood-gas values. Air exposure and delays can produce clinically significant changes. |
| Heparinized Microcollection Tube | Green or laboratory-specified color | Small-volume heparinized plasma or whole blood | Pediatric or low-volume chemistry and selected point-of-care tests validated for microcollection specimens | Requires a smaller blood volume and may reduce the need for venipuncture in patients with limited circulating blood volume | Collect the recommended volume, mix gently without vigorous shaking, and process using the laboratory’s microcollection procedure. | Underfilling, clotting, hemolysis, and limited specimen volume can compromise results. Not all automated analyzers accept microcollection tubes. |