DHA Medical Knowledge 1 — Questions and Answers
Question 1: A 45-year-old male presents with sudden onset chest pain radiating to the left arm, diaphoresis, and shortness of breath. His ECG shows ST-segment elevation in leads II, III, and aVF. Which coronary artery is most likely occluded?
- Left anterior descending artery
- Right coronary artery (Correct answer)
- Left circumflex artery
- Left main coronary artery
Correct answer: Right coronary artery
ST-segment elevation in leads II, III, and aVF indicates an inferior wall myocardial infarction, which is most commonly caused by occlusion of the right coronary artery (RCA). The RCA supplies the inferior wall of the left ventricle and the right ventricle in most patients.
Question 2: A patient with type 2 diabetes mellitus has a fasting blood glucose of 180 mg/dL and HbA1c of 9.2%. Which mechanism of action best describes metformin, the first-line pharmacotherapy for this condition?
- Stimulates insulin secretion from pancreatic beta cells
- Inhibits hepatic glucose production and improves insulin sensitivity (Correct answer)
- Blocks intestinal glucose absorption by inhibiting alpha-glucosidase
- Increases renal glucose excretion by inhibiting SGLT-2
Correct answer: Inhibits hepatic glucose production and improves insulin sensitivity
Metformin primarily works by inhibiting hepatic gluconeogenesis (reducing liver glucose output) and improving peripheral insulin sensitivity. It does not stimulate insulin secretion, making it unlikely to cause hypoglycemia when used as monotherapy.
Question 3: During a respiratory assessment, a physician notes dullness to percussion, increased tactile fremitus, and bronchial breath sounds over the right lower lobe. These findings are most consistent with which diagnosis?
- Pleural effusion
- Pneumothorax
- Lobar pneumonia (Correct answer)
- Emphysema
Correct answer: Lobar pneumonia
Lobar pneumonia causes consolidation of lung tissue, which explains all three findings: dullness to percussion (solid tissue instead of air), increased tactile fremitus (sound transmission enhanced through solid tissue), and bronchial breath sounds (heard over consolidated lung). Pleural effusion also causes dullness but decreases fremitus.
Question 4: A 28-year-old woman in her 32nd week of pregnancy presents with severe headache, visual disturbances, and a blood pressure of 158/105 mmHg. Urinalysis reveals 3+ proteinuria. What is the most appropriate immediate management?
- Administer oral labetalol and discharge with close follow-up
- Immediate cesarean section regardless of fetal status
- Hospitalize, administer magnesium sulfate, and antihypertensives (Correct answer)
- Increase salt intake and bed rest at home
Correct answer: Hospitalize, administer magnesium sulfate, and antihypertensives
This presentation is consistent with severe preeclampsia (BP ≥160/110 mmHg with symptoms and proteinuria). Immediate hospitalization is required. Magnesium sulfate is given for seizure prophylaxis (to prevent eclampsia), and antihypertensives (e.g., labetalol, hydralazine) are given to control severe hypertension. Delivery timing depends on gestational age and clinical stability.
Question 5: A 7-year-old boy is brought to the clinic with a 3-week history of productive cough, low-grade fever, and malaise. His chest X-ray shows bilateral interstitial infiltrates. Cold agglutinin test is positive. Which organism is the most likely causative agent?
- Streptococcus pneumoniae
- Mycobacterium tuberculosis
- Mycoplasma pneumoniae (Correct answer)
- Haemophilus influenzae
Correct answer: Mycoplasma pneumoniae
Mycoplasma pneumoniae is the classic cause of 'walking pneumonia' in school-age children and young adults. It presents with a gradual onset of dry (then productive) cough, low-grade fever, and bilateral interstitial infiltrates. A positive cold agglutinin test is a classic clue, as Mycoplasma induces IgM antibodies that agglutinate red blood cells at cold temperatures.
Question 6: A 60-year-old male with a history of chronic alcohol use presents with confusion, ophthalmoplegia, and ataxia. Which vitamin deficiency is responsible for this clinical triad?
- Vitamin B12 (cobalamin)
- Vitamin B1 (thiamine) (Correct answer)
- Vitamin B6 (pyridoxine)
- Vitamin C (ascorbic acid)
Correct answer: Vitamin B1 (thiamine)
The triad of confusion, ophthalmoplegia (eye movement abnormality), and ataxia is classic for Wernicke's encephalopathy, caused by thiamine (Vitamin B1) deficiency. This is commonly seen in chronic alcoholics due to poor nutrition and impaired thiamine absorption. Immediate IV thiamine administration is critical to prevent progression to Korsakoff syndrome.
DHA Medical Knowledge 1
A 45-year-old male presents with sudden onset chest pain radiating to the left arm, diaphoresis, and shortness of breath.
His ECG shows ST-segment elevation in leads II, III, and aVF.
Which coronary artery is most likely occluded?