Dr. Khalid’s Explanations of 1700 MCQs for PLAB 1

1. A 65yo man presents with painless hematuria, IVU is normal, prostate is mildly enlarged with mild frequency. What is the most appropriate next step?
a. US Abdomen
b. Flexible cystoscopy
c. MRI
d. Nuclear imaging
e. PSA

Ans. The key is B. Flexible cystoscopy. [Painless hematuria in an elderly (here 65 years old man) indicates carcinoma bladder for which flexible cystoscopy is done.
Here BEP is not advanced to cause hemorrhage. There is mild enlargement of prostate and mild symptoms of prostration and hemorrhage is unlikely at this initial stage of BEP which makes Bladder cancer as the likely cause of painless hematuria.
It is also less likely to be prostate cancer as symptoms of prostration are mild (indicates disease is not advanced). Moreover bleeding in cancer prostate is less common].

2. A 74yo smoker presented to his GP with cough and SOB. Exam revealed pigmentation of the oral mucosa and also over the palms and soles. Tests show that he is diabetic and hypokalemic. What is the most probable dx?
a. Pseudocushing syndrome
b. Conns disease
c. Ectopic ACTH
d. Cushings disease
e. Hypothyroidism

Ans. The key is C. Ectopic ACTH. [The patient is smoker and probably developed squamous cell lung cancer which is working as a tumour producing ectopic ACTH causing pigmentation. Resulting raised cortisole is leading to diabetes and hypokalemia (though small cell carcinoma is usual cause but squamous cell carcinoma can produce ectopic ACTH as paraneoplastic syndrome also)].

3. A 44yo woman has lost weight over 12 months. She has also noticed episodes where her heart beats rapidly and strongly. She has a regular pulse rate of 90bpm. Her ECG shows sinus rhythm. What is the most appropriate inv to be done?
a. Thyroid antibodies
b. TFT
c. ECG
d. Echocardiogram
e. Plasma glucose

Ans. The key is B. TFT. [The patient has paroxysmal atrial fibrillation That is why there is no arrhythmia in between attacks. From the given option TFT is the appropriate test as thyrotoxycosis is a leading cause of paroxysmal atrial fibrillation and this ladies weight loss also makes thyrotoxycosis as the probable cause here].

4. A 79yo anorexic male complains of thirst and fatigue. He has symptoms of frequency, urgency and terminal dribbling. His urea and creatinine levels are high. His serum calcium is 1.9 and he is anemic. His BP is 165/95 mmHg. What is the most probable dx?
a. BPH
b. Prostate carcinoma
c. Chronic pyelonephritis
d. Benign nephrosclerosis

Ans. The key is B. Prostate Carcinoma.
Explanation for Question no. 4:
First to say in this case (almost all features goes in favour of prostatic carcinoma like- frequency, urgency and terminal dribbling are features of prostatism; Age, anorexia and anaemia are constitutional features of carcinoma prostate and it would be accurate presentation if it was hypercalcaemia. But given calcium level is of hypocalcaemic level and it is the main cause of discrepancy of this question). Renal failure can be an association of malignant disease and can cause high BP. Thirst is a feature of hypercalcaemia (here may be erroneously calcium level is given in hypocalcaemic level ; probably a bad recall). Prostate biopsy is the confirmatory diagnosis and others like PSA is suggestive.
***There are some suggestion that Renal Failure may be the cause of hypocalcemia.

5. A 64yo man has recently suffered from an MI and is on aspirin, atorvastatin and ramipril. He has been having trouble sleeping and has been losing weight for the past 4 months. He doesn’t feel like doing anything he used to enjoy and has stopped socializing. He says he gets tired easily and can’t concentrate on anything. What is the most appropriate tx?
a. Lofepramine
b. Dosulepin
c. Citalopram
d. Fluoxetine
e. Phenelzine
Ans. The key is C. Citalopram. [Among SSRIs Sertraline is the drug of choice for ischemic heart disease.
Next choice is citalopram (as it is often related to torsades de pointes it is not 1st choice). If SSRI cannot be used Mirtazapine is recommended as next antidepressant].

6. A 67yo man after a stroke, presents with left sided ptosis and constricted pupil. He also has loss of pain and temp on the right side of his body and left side of his face. Which part of the brain is most likely affected?
a. Frontal cortex
b. Cerebellum
c. Pons
d. Medulla
e. Parietal cortex