Section 1.1 Part 3

HF presents to the emergency department and states that he took an overdose of his "heart medication." He does not remember the name of the medication but states he took a handful of tablets approximately 3 hours ago and now feels lethargic and sick in his stomach. His vitals reveal a heart rate of 45 beats/min, blood pressure of 85/40 mm Hg, respiratory rate of 12 breaths/min, and temp of 98.6°F. The ED staff contacts the patient's pharmacy and is told the patient has prescriptions for atenolol, amlodipine, and digoxin. Laboratory test is ordered and is pending. Which of the following agents should not be administered prior to return of digoxin serum concentration determination?

• Atropine

• Fluid bolus

• Calcium salt

• Glucagon

• All of the above

Answer explanation

Administration of calcium salts is appropriate in the treatment of calcium channel blocker toxicity and may be effective in beta-blocker toxicity but should not be utilized in the setting of bradycardia and hypotension where digoxin cannot be ruled out as a cause or confounding factor. Administration of calcium salts in the setting of digoxin poisoning theoretically may worsen toxicity by increasing intracellular calcium levels and could precipitate asystole.

Choice (A) is incorrect. Atropine is a first-line agent in the treatment of bradycardia due to beta-blocker, calcium channel blocker, or digoxin toxicity.

Choice (B) is incorrect. Appropriate fluid bolus is a first-line therapy for hypotension due to beta-blocker or calcium channel blocker toxicity and would not be expected to adversely affect patient with concomitant digoxin.

Choice (D) is incorrect. Administration of glucagon is appropriate in the treatment of beta-blocker toxicity and may be effective in calcium channel blocker toxicity. Glucagon is not a therapy utilized to treat digoxin toxicity, but it would not be contraindicated to use in settings of mixed agent poisoning.

Choice (E) is incorrect.

44% of users answered correctly.

 

Which laboratory test measures the size of a red blood cell?

• Mean corpuscular volume

• Hematocrit

• Red cell distribution width

• Total iron-binding capacity

• Red blood cell

Answer explanation

Mean corpuscular volume (MCV), (A), is a widely used laboratory value to measure the size of a red blood cell. Higher MCV values indicate macrocytosis and lower values indicate microcytosis.

Hematocrit (B) is the percent of blood that the erythrocytes encompass. Red cell distribution width (RDW), (C), when elevated, means the presence of many different sizes of red blood cells; therefore, the MCV is less reliable. Total iron-binding capacity (TIBC), (D), measures the capacity of transferrin to bind to iron. TIBC is elevated in iron deficiency anemia. A red blood cell (E) test measures the number of erythrocytes in a volume of blood.

83% of users answered correctly.

 

GM is a 58-year-old African American man with systolic heart failure presenting with a 10-day history of shortness of breath which limits his normal daily activities and increases lower extremity edema. His weight has recently increased by 12 lb. His physical examination is notable for BP 144/77 mm Hg, HR 85 bpm, RR 22 rpm, rales, and 4+ lower extremity edema. Pertinent laboratory values include: sodium 136 mmol/L, potassium 5.4 mmol/L, BUN 23 mg/dL, creatinine 1.1 mg/dL, and digoxin 1.9 ng/mL. Past medical history is significant for hypertension (HTN), gout, COPD, and atrial fibrillation. Current medications include lisinopril 20 mg daily, diltiazem CD 120 mg daily, digoxin 0.250 mg daily salmeterol/fluticasone 250/50, two puffs bid. GM recently began taking naproxen 220 mg tid for gout pain. Furosemide is initiated at 40 mg twice daily to manage fluid overload. Within the following 24 hours, GM experiences a brisk diuresis with improvement in heart failure signs and symptoms. The naproxen is discontinued to avoid exacerbating fluid retention, and colchicine is initiated at 0.6 mg bid to manage acute gout flares. Once optimal fluid status is achieved, diltiazem is discontinued and carvedilol initiated at 3.125 mg twice daily to manage hypertension. What additional medication change should be considered to decrease morbidity outcomes (e.g. hospitalizations) for GM?

• Increase lisinopril to 40 mg daily.

• Reduce digoxin to 0.125 mg daily.

• Initiate spironolactone 25 mg daily.

• Initiate candesartan 4 mg daily.

Answer explanation

While digoxin does not reduce mortality in HF, it has been shown to reduce hospitalization and improve symptoms. The goal serum digoxin concentration is < 1 ng/mL and serum digoxin concentrations >1 ng/mL may negatively impact GM's morbidity and even mortality. GM's digoxin dose should be reduced to 0.125 mcg daily in an attempt to lower his serum digoxin concentration <1 ng/mL.

Answer (A) is incorrect. Although up-titration of ACE inhibitors to target doses reduces mortality, GM's current potassium level does not allow for the up-titration because hyperkalemia secondary to ACE inhibitor therapy is dose-related.

Answer (C) is incorrect. Adding spironolactone is not indicated unless GM has moderately severe to severe (NYHA class III-IV) symptoms despite standard HF therapy. In addition, current hyperkalemia precludes initiation of this potassium-sparing therapy.

Answer (D) is incorrect. Candesartan is also likely to worsen GM's current hyperkalemia and should be avoided at this time. The benefit of adding an ARB to standard HF therapy is not as clinically meaningful as adding an aldosterone antagonist (e.g. spironolactone). In addition, dual therapy with both an ARB and aldosterone antagonist in addition to background ACE inhibitor therapy is discouraged due to the additive risk of hyperkalemia with all three agents. In fact, such "triple therapy" is given a class III recommendation (harm > benefit) in the ACC/AHA guidelines.

37% of users answered correctly.

 

Select the innate cell that represents the majority of granulocytes and serves as the primary defense against bacterial infections.

• Lymphocytes

• Neutrophils

• Monocytes

• Eosinophils

• Basophils

Answer explanation

Neutrophils represent the majority of granulocytes (80%-90%) and leukocytes (40%-70%) and serve as the primary defense against bacterial infections. Neutrophils, also termed as segs or polymorphonuclear cells, migrate from the bloodstream into infected or inflamed tissue. In this migration process known as chemotaxis, neutrophils reach the desired site and recognize, adhere to, and phagocytose pathogens. During phagocytosis, the pathogen is internalized within the phagocyte. The neutrophil releases its granular contents, which lead to destruction of the engulfed pathogen.

65% of users answered correctly.

 

A 19-year-old man with no known medical history is brought to the emergency department (ED) in a difficult-to-arouse state. His parents report he has been complaining of a vague abdominal pain earlier in the morning, and then began vomiting and urinating frequently in the hours before admission. Urine and blood were positive for ketones. The following laboratory values were taken: Na 142 mEq/L, K 4.5 mEq/L, Cl 100 mEq/L, HCO3 10 mEq/L, glucose 795 mg/dL, pH 7.26, and Pa CO2 23 mm Hg. What is the most likely primary acid-base disturbance?

• Increased anion gap metabolic acidosis

• Normal anion gap metabolic acidosis

• Metabolic alkalosis

• Respiratory acidosis

Answer explanation

The patient is vomiting, urinating frequently, and is difficult to arouse. There is no reason to suspect any pulmonary processes based upon the information given, so we must be thinking a primary metabolic disorder. Looking at the pH, we determine the patient to be acidotic. The PaCO 2 is low, indicating a potential respiratory alkalosis, while the HCO 3 is low, indicating a metabolic acidosis. When we discover this, it is recommended to next check the anion gap, and it is (142 ? 100 ? 10) 32. Without an albumin, we estimate the patient's normal anion gap to be 12, thus the anion gap is elevated (A). This is a classic case of diabetic ketoacidosis, where a patient has been exhibiting symptoms of hyperglycemia, which eventually lead to his near comatose state. Because the cells are starved of energy (no glucose is being utilized due to a lack of insulin), ketone bodies (unmeasured anions) are produced from the breakdown of free fatty acids for energy. Therefore, an increase in the anion gap will be exhibited in DKA.

As indicated, there is no reason to suspect any pulmonary processes (B) based upon the information given. The patient has an acidosis not an alkalosis (C). The primary process is metabolic in nature, not respiratory (D).

60% of users answered correctly.

 

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?

• An electrocardiogram 1 week after chemotherapy

• A complete blood count including platelets 1 week after administration of the chemotherapy

• Serum bilirubin and aspartate transaminase 1 week after chemotherapy

• Urinalysis 1 week after chemotherapy

Answer explanation

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.

42% of users answered correctly.

 

Which of the following findings are most consistent with the diagnosis of pre-renal AKI?

• Specific gravity 1.029, FeNa 0.72%, uOsmol 550 mOsm/kg

• Specific gravity 1.013, FeNa 1.72%, uOsmol 350 mOsm/L

• Specific gravity 1.009, FeNa 2.02%, uOsmol 213 mOsm/L

• Urinalysis: 1+ protein, 10 to 15 RBC, 10 to 15 WBC

• Urinalysis: 3+ protein, no RBC, no WBC

Answer explanation

A high specific gravity, low FeNa, and high urine osmolality is indicative of a pre-renal AKI, a state in which the kidneys will avidly reabsorb sodium and water in an attempt to increase the perfusion to the kidneys and increase the intraglomerular pressure (A).

The specific gravity suggests normal urine density. The FeNa is within the normal range of 1% to 2%. The urine osmolality is also normal. These urine findings are not suggestive of any specific kidney damage (B). In this situation, the specific gravity is low, suggesting a diluted urine. The FeNa is possibly a little elevated, suggesting excess sodium loss. The urine osmolality is a bit low. These findings are the opposite of what might be seen in a pre-renal AKI (C). The protein and cellular matter in this urinalysis are suggestive of some type of intrinsic AKI. Typically, in pre-renal AKI there will not be any particulate matter in the urine (D). This urinalysis shows isolated, significant, proteinuria. Proteinuria suggests a defect within the glomerulus and intrinsic damage, not pre-renal AKI (E).

46% of users answered correctly.

 

CC is a 64-year-old man with a history of chronic kidney disease and heart failure. His baseline SCr is 1.6 mg/dL, with a corresponding CrCl of approximately 50 mL/min. Today, he is brought by ambulance to the emergency room with dyspnea at rest and lower extremity edema all the way up to his thighs. His laboratory analysis shows a SCr of 3.2 mg/dL, and he does not recall urinating at all in the past 24 hours. Which of the following statements is true regarding the estimation of CC's kidney function today?

• Patient's CrCl is essentially zero, as his is not making urine.

• Patient's CrCl is approximately 25 mL/min.

• Patient's CrCl is still approximately 50 mL/min.

• Patient has AKI, and so we cannot estimate his CrCl.

• Wait to calculate patient's CrCl until after giving diuretics.

Answer explanation

Clearance is defined as the volume of solvent cleared of solute per unit time. If the patient is not urinating, his clearance is essentially zero.

Answer (B) is incorrect. This answer seems appropriate given that the patient's SCr has doubled. Doubling of the SCr would cause the CrCl to decrease by one-half, from 50 mL/min to 25 mL/min. However, the SCr is the amount of creatinine in the serum at the time. If the patient stops urinating the GFR is zero, but the SCr will not reflect this change until more SCr is made and accumulates in the serum. The laboratory value lags behind the clinical situation.

Answer (C) is incorrect. The patient's CrCl on presentation was approximately 50 mL/min. Now that he is not urinating and his SCr has started to increase, this value is no longer valid. This baseline value would be a good reference point and goal to achieve during his recovery from AKI.

Answer (D) is incorrect. While it is true that our equations to quantify kidney function are not very accurate during AKI, we must use the information and our professional judgment to recommend appropriate drug therapy for this patient.

Answer (E) is incorrect. While diuretics may be able to convert anuria/oliguria to nonoliguria, the patient may require other pharmacotherapy in the meantime. For instance, the patient may require inotropes for his heart failure before diuresis can be attempted.

59% of users answered correctly.

A patient reports that he has been taking his finasteride and consuming 60 ounces of water daily for the last 6 months for BPH. His last PSA was 2.7 ng/mL. Today it is 1.2 ng/mL. This can be best explained by which of the following?

• Finasteride stops the prostate from producing PSA

• Finasteride can cause erroneous results in laboratory testing for PSA

• PSA levels are often significantly decreased in patients taking 5ARI

• Water intake

Answer explanation

As finasteride decreases the size of the prostate, there is less prostate volume to produce PSA. PSA levels can be expected to decrease as much as 50% after beginning therapy with either finasteride or dutasteride (C).

The prostate still produces PSA after patients begin taking 5ARI therapy (A). The decrease in PSA is not an anomaly associated with erroneous laboratory testing for PSA (B). While all patients should maintain adequate hydration, water intake (D) would not have an impact on the PSA.

62% of users answered correctly.

 

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

• 2 hours after dose

• 4 hours after dose

• 6 hours after dose

• 8 hours after dose

Answer explanation

 

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.

43% of users answered correctly.