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 A
Explanation
Choice A reason:
The left antecubital area is the correct site to perform venipuncture on a patient who has had a right-sided mastectomy. It is recommended to avoid the side of the mastectomy due to the risk of lymphedema and other complications associated with the removal of lymph nodes during the surgery. The left antecubital fossa, which is the area in front of the elbow, is a common site for venipuncture and is generally safe for use when the right side cannot be used.
Choice B reason:
The right cephalic vein should be avoided in a patient with a right-sided mastectomy. Venipuncture on the same side as the mastectomy can increase the risk of complications, including lymphedema, which is a condition characterized by swelling due to lymph fluid accumulation. Therefore, the right cephalic vein is not an appropriate choice.
Choice C reason:
The left femoral artery is not a venipuncture site; it is an arterial site. Venipuncture refers to accessing a vein, not an artery, for blood collection. Additionally, arterial puncture is a more invasive procedure typically reserved for arterial blood gas analysis and is not performed for routine venipuncture.
Choice D reason:
Similar to choice B, the right basilic vein should be avoided for venipuncture in a patient who has had a right-sided mastectomy. The basilic vein is located on the inner side of the arm and using it could pose the same risks as using the right cephalic vein, including the potential for lymphedema.
Correct Answer is D
Explanation
Choice A Reason:
Inverting the tube 5 to 7 times may not be sufficient to mix the blood thoroughly with the EDTA. This could lead to partial clotting and potentially inaccurate test results. The EDTA anticoagulant works by binding calcium ions, which are necessary for blood clotting. Without adequate mixing, the EDTA may not be evenly distributed, leaving some areas of the blood sample able to clot.
Choice B Reason:
Inverting the tube only 2 to 4 times is inadequate for proper mixing. This minimal agitation would likely result in clot formation because the anticoagulant would not be sufficiently mixed with the blood. Clots can interfere with the accuracy of hematological tests by trapping cells and altering the specimen's composition.
Choice C Reason:
Inverting the tube 1 to 3 times is clearly insufficient and would almost certainly lead to clotting. The purpose of inverting the tube is to ensure that the EDTA coats all the blood cells, preventing coagulation. Such a low number of inversions would not allow for the anticoagulant to perform its function effectively.
Choice D Reason:
Inverting the tube 8 to 10 times is the recommended practice. This number of inversions ensures that the blood is fully mixed with the EDTA, preventing clot formation and preserving the integrity of the sample for accurate laboratory analysis. It is important to perform these inversions gently to avoid hemolysis, which can also affect test results. Hemolysis occurs when red blood cells are damaged and their contents leak out, which can happen if the blood is shaken too vigorously.
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