Which of the following information should be included with a non-blood specimen that is delivered to the laboratory?

Choice A reason:
The order of citrate, heparin, EDTA, and fluoride is not the correct sequence for blood collection. The correct order is essential to prevent cross-contamination of additives between tubes, which could interfere with test results. Citrate tubes should be drawn first to ensure that the blood does not clot prematurely, but heparin should not follow immediately after citrate.

Choice B reason:
Citrate tubes, which contain sodium citrate, are used for coagulation tests and must be drawn first to ensure the proper blood-to-additive ratio. EDTA tubes are drawn next because EDTA binds calcium and prevents clotting, making it ideal for complete blood counts and other hematology studies. Heparin tubes, which prevent clotting by inhibiting thrombin and thromboplastin, are drawn after EDTA. Lastly, fluoride tubes, which contain a glycolysis inhibitor, are drawn to preserve glucose levels and are typically used for glucose and lactate testing.

Choice C reason:
Starting with fluoride is not recommended as it could lead to contamination of the EDTA and heparin tubes with fluoride, which could affect the results of certain tests, such as calcium determinations in heparin tubes. The order of draw is designed to minimize such risks.

Choice D reason:
This sequence is incorrect because fluoride tubes are not drawn before EDTA and heparin tubes. The presence of fluoride could potentially contaminate the subsequent tubes and alter the results of the tests that require heparin or EDTA as an anticoagulant.

In phlebotomy, following the correct order of draw is crucial. The order is established based on the type of additive in each tube and its potential to interfere with tests conducted in subsequent tubes. The standard order is: blood cultures, citrate tubes, serum tubes with or without clot activator and gel, heparin tubes with or without gel, EDTA tubes, and lastly, fluoride tubes. This sequence helps prevent cross-contamination and ensures the accuracy of laboratory results, which are critical for patient diagnosis and treatment.

Choice A Reason:
Asking "When was your last dose of lithium?" is crucial for therapeutic drug monitoring (TDM). TDM is used to tailor dosages and maintain therapeutic levels in a patient’s bloodstream, especially for drugs with narrow therapeutic indices like lithium. The timing of the last dose can significantly affect blood levels, and knowing this information helps in interpreting the results accurately.

Choice B Reason:
While knowing the fasting status of a patient may be relevant for certain tests, it is not typically critical for TDM unless the medication being monitored is affected by food intake. Lithium levels are not significantly influenced by fasting, so this question is less relevant than knowing the timing of the last dose.

Choice C Reason:
Inquiring about the last alcoholic beverage is important if alcohol could interfere with the medication's metabolism or the test's accuracy. However, for lithium TDM, alcohol consumption is not as directly relevant as the timing of the last dose. Alcohol does not typically alter lithium levels unless it affects the patient's hydration status.

Choice D Reason:
Asking if the patient has finished drinking the glucose solution would be pertinent if conducting a glucose tolerance test. However, this is not relevant for TDM of lithium, as the glucose solution does not interfere with lithium levels or the TDM process.

In conclusion, for therapeutic drug monitoring, particularly for lithium, the most critical question is regarding the timing of the last dose. This information is essential to ensure that the blood levels reflect the peak or trough concentration, depending on what is being measured, and to avoid misinterpretation that could lead to inappropriate dosing adjustments.