A nurse is reporting a client’s laboratory tests to the provider to obtain a prescription for the client’s daily warfarin.
Which of the following laboratory tests should the nurse plan to report to obtain the prescription for the warfarin?
INR
Fibrinogen level
aPTT
Platelet count
The Correct Answer is A
The correct answer is choice A. INR.
Warfarin is a vitamin K antagonist that inhibits the synthesis of factors II, VII, IX, and X in the liver.
These factors are part of the extrinsic and common pathways of coagulation, which are measured by the prothrombin time (PT) and the international normalized ratio (INR).
The INR is a standardized way of reporting the PT that accounts for the variability of different reagents and instruments.
The INR is used to monitor the therapeutic effect of warfarin and to adjust the dose accordingly.
The target INR range depends on the indication for warfarin, but it is usually between 2 and 3 for most conditions.
Choice B is wrong because fibrinogen level is not affected by warfarin.
Fibrinogen is a precursor of fibrin, which forms the final step of the coagulation cascade.
Fibrinogen level can be decreased in conditions such as disseminated intravascular coagulation (DIC), liver disease, or severe bleeding. Choice C is wrong because aPTT is not affected by warfarin.
aPTT measures the intrinsic and common pathways of coagulation, which are mainly dependent on factors VIII, IX, XI, and XII.
These factors are not inhibited by warfarin.
aPTT is used to monitor the effect of heparin, a direct antithrombin agent that inhibits thrombin and factor Xa.
Choice D is wrong because platelet count is not affected by warfarin.
Platelets are cell fragments that adhere to damaged blood vessels and form aggregates to initiate hemostasis.
Platelet count can be decreased in conditions such as immune thrombocytopenia (ITP), heparin-induced thrombocytopenia (HIT), or bone marrow suppression.
Normal ranges:
- INR: 0.8-1.2
- Fibrinogen: 200-400 mg/dL
- aPTT: 25-35 seconds
- Platelet count: 150-450 x 10^9/L References:
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
The correct answer is choiced. A client who is taking warfarin and has an INR of 1.8.
Choice A rationale:
An induration after a Mantoux test indicates a positive reaction, but it does not necessarily require immediate follow-up unless the induration is significant and the client has risk factors for tuberculosis.
Choice B rationale:
Sodium phosphate is commonly used as a bowel preparation for colonoscopy. This does not typically require follow-up unless the client experiences adverse effects such as dehydration or electrolyte imbalance.
Choice C rationale:
A potassium level of 3.6 mEq/L is within the normal range (3.5-5.0 mEq/L). Therefore, this finding does not require follow-up.
Choice D rationale:
An INR of 1.8 for a client taking warfarin is below the therapeutic range for most indications (typically 2.0-3.0). This requires follow-up to adjust the warfarin dosage to achieve the desired anticoagulation effect.
Correct Answer is C
Explanation
- . Answer and explanation.
The correct answer is choice C, first-degree atrioventricular block.
This is because the PR interval is longer than normal, which indicates a delay in the conduction of electrical impulses from the atria to the ventricles through the AV node. A normal PR interval is 0.12 to 0.2 seconds, or 3 to 5 small squares on the EKG strip.
In this case, the PR interval is 0.35 seconds, which is more than 5 small squares.
Choice A is wrong because atrial fibrillation is a type of arrhythmia where the atria beat irregularly and rapidly, producing chaotic and variable P waves and an irregular ventricular response.
There is no constant PR interval in atrial fibrillation.
Choice B is wrong because complete heart block is a type of arrhythmia where there is no conduction of electrical impulses from the atria to the ventricles, resulting in independent and dissociated atrial and ventricular rhythms.
There are no consistent P waves or PR intervals in complete heart block.
Choice D is wrong because premature atrial complexes are extra beats that originate from the atria and interrupt the normal sinus rhythm.
They produce abnormal P waves that are different from the sinus P waves, and may have a shorter or longer PR interval depending on the timing of the impulse.
However, they do not cause a constant prolongation of the PR interval.
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