DHA Medical Knowledge 3 — Questions and Answers
Question 1: A 58-year-old patient on warfarin is prescribed ciprofloxacin for a urinary tract infection. What is the most important monitoring consideration?
- Renal function tests every 48 hours
- INR levels, as ciprofloxacin potentiates warfarin's anticoagulant effect (Correct answer)
- Liver enzymes, as the combination is hepatotoxic
- Blood glucose, as fluoroquinolones cause hypoglycemia
Correct answer: INR levels, as ciprofloxacin potentiates warfarin's anticoagulant effect
Ciprofloxacin inhibits the metabolism of warfarin by suppressing gut flora that produce vitamin K and by inhibiting CYP1A2, leading to elevated INR and increased bleeding risk. Close INR monitoring and possible warfarin dose reduction are required.
Question 2: Which of the following is the MOST common opportunistic infection seen in HIV-positive patients with a CD4 count below 200 cells/μL?
- Cryptococcal meningitis
- Toxoplasma encephalitis
- Pneumocystis jirovecii pneumonia (PCP) (Correct answer)
- Cytomegalovirus retinitis
Correct answer: Pneumocystis jirovecii pneumonia (PCP)
Pneumocystis jirovecii pneumonia (PCP) is the most common AIDS-defining opportunistic infection when the CD4 count drops below 200 cells/μL. Prophylaxis with trimethoprim-sulfamethoxazole is recommended at this threshold. The other infections typically occur at lower CD4 counts.
Question 3: A 45-year-old woman presents with fatigue, weight gain, cold intolerance, and constipation. Her TSH is 12 mIU/L and free T4 is low. What is the first-line treatment?
- Liothyronine (T3) supplementation
- Levothyroxine (T4) replacement therapy (Correct answer)
- Propylthiouracil (PTU)
- Radioactive iodine therapy
Correct answer: Levothyroxine (T4) replacement therapy
The clinical picture and lab findings are consistent with primary hypothyroidism. Levothyroxine (synthetic T4) is the standard first-line treatment. It is converted peripherally to the active T3 form. PTU and radioactive iodine are used for hyperthyroidism, not hypothyroidism.
Question 4: A patient develops sudden-onset severe headache described as 'the worst headache of my life,' with neck stiffness and photophobia. CT head is negative. What is the NEXT most critical diagnostic step?
- MRI brain with contrast
- Lumbar puncture to examine cerebrospinal fluid (Correct answer)
- Empiric treatment with sumatriptan for migraine
- EEG to rule out seizure activity
Correct answer: Lumbar puncture to examine cerebrospinal fluid
A 'thunderclap' headache with meningismus and a negative CT scan requires lumbar puncture to rule out subarachnoid hemorrhage (SAH). Up to 5% of SAH cases have a normal CT, and CSF analysis for xanthochromia or red blood cells is the definitive next step. Delaying this test is dangerous.
Question 5: In managing Type 2 Diabetes Mellitus, which medication class has demonstrated the GREATEST cardiovascular mortality benefit in patients with established atherosclerotic cardiovascular disease?
- Sulfonylureas (e.g., glibenclamide)
- DPP-4 inhibitors (e.g., sitagliptin)
- SGLT-2 inhibitors (e.g., empagliflozin) (Correct answer)
- Alpha-glucosidase inhibitors (e.g., acarbose)
Correct answer: SGLT-2 inhibitors (e.g., empagliflozin)
SGLT-2 inhibitors, particularly empagliflozin (EMPA-REG OUTCOME trial) and canagliflozin (CANVAS trial), have demonstrated significant reductions in cardiovascular death, heart failure hospitalization, and kidney disease progression in T2DM patients with established cardiovascular disease, making them a preferred add-on to metformin in this population.
Question 6: A neonate born at 36 weeks gestation develops respiratory distress within 4 hours of birth, showing grunting, nasal flaring, and subcostal retractions. Chest X-ray shows a 'ground-glass' appearance with air bronchograms. What is the MOST likely diagnosis?
- Meconium aspiration syndrome
- Transient tachypnea of the newborn (TTN)
- Neonatal respiratory distress syndrome (RDS) (Correct answer)
- Congenital pneumonia
Correct answer: Neonatal respiratory distress syndrome (RDS)
Neonatal RDS (formerly hyaline membrane disease) results from surfactant deficiency in preterm infants, typically presenting within hours of birth. The classic chest X-ray findings of diffuse ground-glass opacification with air bronchograms are hallmark features. TTN typically shows perihilar streaking and resolves within 24–48 hours; meconium aspiration shows patchy infiltrates.
DHA Medical Knowledge 3
A 58-year-old patient on warfarin is prescribed ciprofloxacin for a urinary tract infection.
What is the most important monitoring consideration?