A phlebotomist is preparing to draw blood from a patient for therapeutic drug monitoring. Which of the following questions should the phlebotomist ask?
"When was your last dose of lithium?"
"For how long have you been fasting?"
"When did you have your last alcoholic beverage?"
"Have you finished drinking the glucose solution?"
The Correct Answer is A
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.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Choice A Reason:
Prepping the site with povidone iodine is not typically associated with hemoconcentration. Povidone iodine is used as an antiseptic to clean the skin before venipuncture to prevent infection. While it's important to allow it to dry to avoid sample contamination, it does not cause hemoconcentration.
Choice B Reason:
Leaving the tourniquet in place for more than 2 minutes can lead to hemoconcentration. A tourniquet is applied to engorge the veins, making them easier to puncture. However, prolonged application can result in fluid being forced out of the vein into the tissue, increasing the concentration of cells and larger molecules in the blood. This can affect certain laboratory test results by artificially increasing the levels of cellular components.
Choice C Reason:
Not refrigerating the specimen within 30 minutes does not cause hemoconcentration. However, it can affect the stability of certain analytes in the blood sample. Refrigeration is necessary for preserving the integrity of certain components of the blood until analysis, but it is unrelated to the concentration of cells within the sample at the time of collection.
Choice D Reason:
Removing the needle before the tourniquet is released does not cause hemoconcentration. This action might lead to other complications, such as hematoma formation, but it does not affect the concentration of cellular elements in the collected sample.
Correct Answer is C
Explanation
Choice A Reason:
Warfarin does not typically require a fasting state before blood is drawn for testing. The medication's effect on clotting factors is independent of food intake. Therefore, a fasting requirement is not anticipated for patients taking warfarin unless specified for other concurrent tests.
Choice B Reason:
There is no need for an alternate antiseptic due to warfarin use. Standard antiseptic procedures are sufficient when drawing blood from patients on warfarin. The choice of antiseptic would be more influenced by patient allergies or specific institutional protocols.
Choice C Reason:
Patients on warfarin have an increased bleeding time because the medication is an anticoagulant, which means it works to prevent blood clots by thinning the blood. This can lead to prolonged bleeding after a venipuncture, and phlebotomists should be prepared to apply pressure for a longer time to ensure hemostasis.
Choice D Reason:
Placing a specimen on ice is not a standard procedure for blood samples taken for warfarin monitoring, which is typically done through a PT/INR test. This test measures the time it takes for blood to clot and is not affected by temperature in the same way that tests for certain enzymes or gases might be.
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