A nurse is preparing to administer vancomycin IV to an adult client. The client asks the nurse if the medication can be given 2 hr earlier. Which of the following statements should the nurse make?

The correct answer is choice D: A client who is taking warfarin and has an INR of 1.8.

Choice A rationale:

A Mantoux test with an induration after 48 hours can be a normal reaction, especially if the induration is within the expected size range for a positive result, depending on the individual’s risk factors and history. It does not necessarily require follow-up care unless the induration is significantly large or there are other concerning symptoms.

Choice B rationale:

A client scheduled for a colonoscopy and taking sodium phosphate does not typically require follow-up care for the sodium phosphate intake itself. Sodium phosphate is commonly used as a bowel prep medication to clear the intestines prior to the procedure.

Choice C rationale:

A potassium level of 3.6 mEq/L is within the normal range (3.5-5.0 mEq/L), so a client taking bumetanide with this potassium level would not typically require follow-up care for the potassium level alone.

Choice D rationale:

A client taking warfarin with an INR of 1.8 requires follow-up care because the therapeutic range for warfarin is typically between 2.0 and 3.0 for most indications. An INR of 1.8 may indicate that the blood is not “thin” enough, increasing the risk of thrombotic events, and the warfarin dose may need adjustment.

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.