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1.1.4: Obtain, interpret, assess, and/or evaluate laboratory and diagnostic findings

The provider is going to order a serum lithium level for GT. When is the appropriate time to monitor/order a serum lithium level?

(A) 2 hours after dose

(B) 4 hours after dose

(C) 6 hours after dose

(D) 8 hours after dose

The Correct Answer is: D

Since lithium distribution follows a two-compartment model, it is imperative that lithium samples be obtained at consistent and reproducible times. The level should be obtained just before the first morning dose of lithium and at least 12 hours after the last evening dose. However, our patient is receiving the medication every 8 hours, so 12 hours after the last dose sampling time is not feasible. Therefore, 8 hours after the last dose (D) would be the time to sample. The terminal half-life of 18 hours suggests that steady-state lithium levels should be obtained within 3 to 5 days. Although lithium levels appear to plateau within 3 to 5 days, full therapeutic effects are not generally observed for 14 to 21 days after therapy has been initiated.

Sampling times of 2 hours (A), 4 hours (B), and 6 hours (C) are too early.

A premenopausal woman with ER negative, node positive breast cancer is starting doxorubicin and cyclophosphamide adjuvant treatment. What would you recommend to determine the severity of the most common toxicity associated with this treatment regimen?

(A) An electrocardiogram 1 week after chemotherapy

(B) A complete blood count including platelets 1 week after administration of the chemotherapy

(C) Serum bilirubin and aspartate transaminase 1 week after chemotherapy

(D) Urinalysis 1 week after chemotherapy

The Correct Answer is: B

Myelosuppression (neutropenia, thrombocytopenia) is the most common treatment related adverse effect associated with this adjuvant treatment regimen. Nearly 100% of patients receiving this treatment regimen will experience myelosuppression (B).

Doxorubicin has been associated with cardiomyopathy that increases in incidence with cumulative doses exceeding 400 mg/m 2 . The incidence of cardiomyopathy in patients administered cumulative doses exceeding 400 mg/m 2 is in the range of 5%. It is not the most common toxicity associated with this treatment regimen (A). Although these drugs may cause elevations of serum bilirubin and aspartate transaminase (C), it occurs less frequently than myelosuppression. Although urinalysis (D) could be useful in detecting hematuria caused by cyclophosphamide, this adverse effect (hemorrhagic cystitis) occurs infrequently with this adjuvant chemotherapy regimen.

What AED has a target serum concentration of 50 ...

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