Renal excretion mechanisms — MCQs

A patient is receiving daily administrations of Compound X. Compound X is freely filtered in the glomeruli and undergoes net secretion in the renal tubules. The majority of this tubular secretion occurs in the proximal tubule. Additional information regarding this patient's renal function and the renal processing of Compound X is included below: Inulin clearance: 120 mL/min Plasma concentration of Inulin: 1 mg/mL PAH clearance: 600 mL/min Plasma concentration of PAH: 0.2 mg/mL Total Tubular Secretion of Compound X: 60 mg/min Net Renal Excretion of Compound X: 300 mg/min Which of the following is the best estimate of the plasma concentration of Compound X in this patient?

On cardiology service rounds, your team sees a patient admitted with an acute congestive heart failure exacerbation. In congestive heart failure, decreased cardiac function leads to decreased renal perfusion, which eventually leads to excess volume retention. To test your knowledge of physiology, your attending asks you which segment of the nephron is responsible for the majority of water absorption. Which of the following is a correct pairing of the segment of the nephron that reabsorbs the majority of all filtered water with the means by which that segment absorbs water?

A new drug has been shown to block epithelial sodium channels in the cortical collecting duct. Which of the following is most likely to be decreased upon drug administration?

Which transport mechanism is primarily responsible for calcium reabsorption in the proximal tubule?

An investigator is studying the effect of antihypertensive drugs on cardiac output and renal blood flow. For comparison, a healthy volunteer is given a placebo and a continuous infusion of para-aminohippuric acid (PAH) to achieve a plasma concentration of 0.02 mg/ml. His urinary flow rate is 1.5 ml/min and the urinary concentration of PAH is measured to be 8 mg/ml. His hematocrit is 50%. Which of the following values best estimates cardiac output in this volunteer?

A 50-year-old woman presents to the ED 6 hours after ingesting three bottles of baby aspirin. She complains of nausea, vomiting, dizziness, and tinnitus. Her blood pressure is 135/80 mmHg, pulse is 110/min, respirations are 32/min, temperature is 100.1 deg F (37.8 deg C), and oxygen saturation is 99% on room air. Arterial blood gas at room air shows, PCO2 11 mmHg, and PO2 129 mmHg. Blood salicylate level is 55 mg/dL. Management should involve which of the following acid-base principles?

A researcher is investigating the effects of a new antihypertensive medication on renal physiology. She gives a subject a dose of the new medication, and she then collects plasma and urine samples. She finds the following: Hematocrit: 40%; Serum creatinine: 0.0125 mg/mL; Urine creatinine: 1.25 mg/mL. Urinary output is 1 mL/min. Renal blood flow is 1 L/min. Based on the above information and approximating that the creatinine clearance is equal to the GFR, what answer best approximates filtration fraction in this case?

A 17-year-old woman is rushed into the emergency department by her father who found her collapsed in her bedroom 15 minutes before the ambulance's arrival. There was an empty bottle of clomipramine in her bedroom which her mother takes for her depression. Vital signs include the following: respiratory rate 8/min, pulse 130/min, and blood pressure 100/60 mm Hg. On physical examination, the patient is unresponsive to vocal and tactile stimuli. Oral mucosa and tongue are dry, and the bladder is palpable. A bedside electrocardiogram (ECG) shows widening of the QRS complexes. Which of the following would be the best course of treatment in this patient?

A 59-year-old man presents with intense, sharp pain in his toe for the past hour. He reports similar symptoms in the past and this is his 2nd visit to the emergency department this year with the same complaint. The patient is afebrile and the vital signs are within normal limits. On physical examination, there is significant erythema, swelling, warmth, and moderate pain on palpation of the right 1st toe. The remainder of the examination is unremarkable. A plain radiograph of the right foot reveals no abnormalities. Joint arthrocentesis of the inflamed toe reveals urate crystals. Laboratory studies show: Serum glucose (random) 170 mg/dL Sodium 140 mEq/L Potassium 4.1 mEq/L Chloride 100 mEq/L Uric acid 7.2 mg/dL Serum creatinine 0.8 mg/dL Blood urea nitrogen 9 mg/dL Cholesterol, total 170 mg/dL HDL-cholesterol 43 mg/dL LDL-cholesterol 73 mg/dL Triglycerides 135 mg/dL HDL: high-density lipoprotein; LDL: low-density lipoprotein Ibuprofen is prescribed for the acute treatment of this patient's symptoms. He is also put on chronic therapy to prevent the recurrence of future attacks. Which of the following drugs is 1st-line for chronic therapy of gout?

A 55-year-old man presents to the urgent clinic complaining of pain in his right foot. He reported that the pain is intense that he had to remove his shoe and sock, and rates the pain level as 6 out of 10. He does not report trauma or recent infection. The past medical history includes hypertension. The medications include hydrochlorothiazide, enalapril, and a daily multivitamin. The family history is noncontributory. He consumes alcohol in moderation. His diet mostly consists of red meat and white rice. The blood pressure is 137/85 mm Hg, heart rate is 74/min, respiratory rate is 12/min, and the temperature is 36.9°C (98.4°F). The physical examination demonstrates swelling, redness, and tenderness to palpation in the first metatarsophalangeal joint of his right foot. There are no skin lesions. The rest of the patient’s examination is normal. An arthrocentesis procedure is scheduled. Which of the following is the most likely pharmacological treatment for the presented patient?