Biochemistry
2 questionsA 34-year-old male whose staple diet primarily consisted of only maize presents with diarrhea, dementia, and photosensitive dermatitis in sun-exposed areas. Which vitamin is most likely deficient in this patient?
A patient who was in excruciating pain all over his body was taken to the hospital. In recent years, he has experienced these episodes frequently. When exercising vigorously, the pain begins. Anemia was detected on blood examination along with sickled RBCs as opposed to normal biconcave ones. It was determined that he had sickle cell anemia. What substitution takes place in sickle cell anemia?
FMGE 2023 - Biochemistry FMGE Practice Questions and MCQs
Question 261: A 34-year-old male whose staple diet primarily consisted of only maize presents with diarrhea, dementia, and photosensitive dermatitis in sun-exposed areas. Which vitamin is most likely deficient in this patient?
- A. Niacin (Correct Answer)
- B. Vitamin B6
- C. Ascorbic acid
- D. Biotin
Explanation: **Correct: Niacin** - The constellation of **dementia**, **diarrhea**, and **photosensitive dermatitis** (the 3 Ds) is the hallmark presentation of **Pellagra**. - A diet reliant on **maize** (corn) is a classic cause of Pellagra because maize is deficient in **tryptophan**, a vital precursor to Niacin (Vitamin B3). - Pellagra can progress to a fourth D (**Death**) if untreated. *Incorrect: Vitamin B6* - Deficiency typically manifests as **peripheral neuropathy**, **seborrheic dermatitis** (non-photosensitive), and microcytic anemia (**sideroblastic anemia**). - It is not associated with the severe chronic diarrhea or the characteristic sun-exposed rash seen in Pellagra. *Incorrect: Ascorbic acid* - Deficiency causes **Scurvy**, characterized by **bleeding gums**, **perifollicular hemorrhages** (petechiae), and **impaired wound healing**. - Neurological symptoms typical of dementia and pronounced gastrointestinal symptoms are not primary features of Scurvy. *Incorrect: Biotin* - Biotin (Vitamin B7) deficiency is rare, usually presenting with **alopecia**, non-specific dermatitis, and sometimes hypotonia or developmental delay. - It is differentiated by the absence of characteristic photosensitive rash and the severe central nervous system symptoms (dementia) that define this case.
Question 262: A patient who was in excruciating pain all over his body was taken to the hospital. In recent years, he has experienced these episodes frequently. When exercising vigorously, the pain begins. Anemia was detected on blood examination along with sickled RBCs as opposed to normal biconcave ones. It was determined that he had sickle cell anemia. What substitution takes place in sickle cell anemia?
- A. Substitution of glutamic acid by valine at the 6th position (Correct Answer)
- B. Substitution of valine by glutamic acid at the 5th position
- C. Substitution of glutamic acid by valine at the 5th position
- D. Substitution of valine by glutamic acid at the 6th position
Explanation: ***Substitution of glutamic acid by valine at the 6th position***- This is the defining molecular defect in **sickle cell anemia** (HbS), resulting from a point mutation (GAG $\rightarrow$ GTG) in the $\beta$-globin gene.- The replacement of the hydrophilic amino acid **glutamic acid** by the hydrophobic amino acid **valine** at the **6th position** facilitates the polymerization of **deoxy-HbS** under low oxygen tension, causing RBC sickling.*Substitution of valine by glutamic acid at the 6th position*- This change is the **opposite** of the mutation causing HbS; HbS involves the substitution of a hydrophilic residue (Glutamic acid) with a **hydrophobic** one (Valine).- This particular reverse substitution would not lead to the formation of the **deoxy-HbS polymers** responsible for the sickling phenomenon.*Substitution of valine by glutamic acid at the 5th position*- The amino acid at the 5th position of the $\beta$-globin chain is typically **proline**, and the crucial molecular abnormality in HbS involves the **6th position**, not the 5th.- The defining mutation involves Glutamic acid being replaced by Valine, not Valine being replaced by Glutamic acid.*Substitution of glutamic acid by valine at the 5th position*- While the amino acid change (Glutamic acid $\rightarrow$ Valine) is correct for the type of substitution, the characteristic mutation of **sickle cell anemia** occurs specifically at the **6th position**.- Substitutions at different positions (like the 5th) usually result in other, distinct hemoglobin variants.
ENT
1 questionsA 35-year-old woman presented to the clinic with the symptoms of hearing loss and pulsatile tinnitus. Further examination reveals conductive hearing loss with the Rinne test negative. A reddish mass is seen behind the tympanic membrane. What is the most likely diagnosis for this patient?
FMGE 2023 - ENT FMGE Practice Questions and MCQs
Question 261: A 35-year-old woman presented to the clinic with the symptoms of hearing loss and pulsatile tinnitus. Further examination reveals conductive hearing loss with the Rinne test negative. A reddish mass is seen behind the tympanic membrane. What is the most likely diagnosis for this patient?
- A. Chronic otitis media
- B. Glomus tumour (Correct Answer)
- C. Serous otitis media
- D. Acute otitis media
Explanation: ***Glomus tumour (Correct Answer)*** - **Pulsatile tinnitus** combined with **conductive hearing loss** and a **reddish retrotympanic mass** forms the classic diagnostic triad for glomus tympanicum (a paraganglioma arising from glomus bodies). - The **reddish vascular mass** behind the tympanic membrane is pathognomonic, sometimes called the **'rising sun sign'** or demonstrating **Brown's sign** (blanching with pneumatic otoscopy). - This slow-growing, highly vascular tumor characteristically presents with these features in middle-aged adults. *Acute otitis media (Incorrect)* - This acute bacterial infection presents with rapid onset of **otalgia** (ear pain), **fever**, and a bulging, intensely red tympanic membrane. - While it causes temporary conductive hearing loss due to **purulent fluid** accumulation, it lacks the chronic presentation and **pulsatile tinnitus** characteristic of vascular masses. - The clinical course is acute (days), not chronic like glomus tumors. *Chronic otitis media (Incorrect)* - Defined by chronic inflammation typically resulting in **tympanic membrane perforation**, recurrent **otorrhea** (ear discharge), and possible **cholesteatoma** formation. - While it causes conductive hearing loss, it does **not** produce **pulsatile tinnitus** or a **reddish, vascular retrotympanic mass**. - The tympanic membrane shows perforation or scarring, not an intact membrane with a vascular mass behind it. *Serous otitis media (Incorrect)* - Also known as **otitis media with effusion**, involves sterile, non-purulent fluid in the middle ear from **eustachian tube dysfunction**. - The tympanic membrane appears dull, retracted, or shows **air-fluid levels** and bubbles, but does not show a vascular mass. - This condition does **not** cause **pulsatile tinnitus** and the fluid is serous, not vascular tissue.
Internal Medicine
1 questionsA patient presented to the OPD with liver damage. The picture depicts the patient having their eyes examined. Which of the following substances is responsible for this condition?
FMGE 2023 - Internal Medicine FMGE Practice Questions and MCQs
Question 261: A patient presented to the OPD with liver damage. The picture depicts the patient having their eyes examined. Which of the following substances is responsible for this condition?
- A. Glucose
- B. Galactose
- C. Mannose
- D. Copper (Correct Answer)
Explanation: ***Copper*** - The image displays a **Kayser-Fleischer ring**, a greenish-gold ring at the corneal limbus, which is a hallmark sign of **Wilson's disease**. This condition, combined with liver damage, points to an issue with copper metabolism. - Wilson's disease is an autosomal recessive disorder caused by a mutation in the **ATP7B gene**, leading to impaired biliary excretion and subsequent toxic accumulation of **copper** in the liver, brain, and cornea. *Glucose* - Elevated **glucose** levels, as seen in diabetes mellitus, can cause ocular complications such as **diabetic retinopathy** and **cataracts**, but not Kayser-Fleischer rings. - While diabetes can be associated with liver disease (e.g., **NAFLD**), the combination of this specific eye finding and liver damage is not characteristic of glucose-related pathology. *Galactose* - Excess **galactose** is characteristic of **galactosemia**, an inherited metabolic disorder that can cause liver failure and cirrhosis, similar to Wilson's disease. - However, the classic ocular finding in galactosemia is the formation of **"oil-droplet" cataracts**, not the Kayser-Fleischer rings shown in the image. *Mannose* - Disorders of **mannose** metabolism are typically classified as **congenital disorders of glycosylation (CDGs)**. - These rare genetic disorders present with a wide spectrum of multi-systemic symptoms, including neurological and developmental issues, but are not associated with the development of Kayser-Fleischer rings.
Pharmacology
6 questionsA patient with a history of hypertension is given the drug 'X'. Identify 'X'?
Which statement best describes the relationship between drug potency and efficacy in dose-response curves?
Which drug elicits the following response on blood pressure and heart rate, as shown in the image?
A female patient complains of swelling and pain in her great toe. Her uric acid level is found to be high. A drug that reduces uric acid levels is prescribed. Which of the following enzymes should the drug inhibit?
Which of the following drugs increases uric acid in urine?
The most appropriate description of the vasomotor reversal of Dale is that
FMGE 2023 - Pharmacology FMGE Practice Questions and MCQs
Question 261: A patient with a history of hypertension is given the drug 'X'. Identify 'X'?
- A. Aliskiren (Correct Answer)
- B. Losartan
- C. Spironolactone
- D. Captopril
Explanation: ***Aliskiren*** - Aliskiren is a **direct renin inhibitor**. The diagram shows that drug 'X' directly inhibits the release or action of **renin** from the kidneys. - By inhibiting renin, it blocks the first and rate-limiting step of the **Renin-Angiotensin-Aldosterone System (RAAS)**, preventing the conversion of **angiotensinogen** to **angiotensin I**. *Captopril* - Captopril is an **Angiotensin-Converting Enzyme (ACE) inhibitor**. It acts later in the pathway to block the conversion of **angiotensin I** to **angiotensin II**. - This mechanism is different from drug 'X', which acts on **renin** at the beginning of the cascade. *Spironolactone* - Spironolactone is an **aldosterone antagonist** and a potassium-sparing diuretic. It acts at the end of the RAAS pathway. - It works by blocking **aldosterone receptors** in the distal tubules of the kidney, preventing sodium and water reabsorption, which is downstream from the action of renin. *Losartan* - Losartan is an **Angiotensin II Receptor Blocker (ARB)**. It prevents **angiotensin II** from binding to its receptors on blood vessels and the adrenal glands. - This action occurs much later in the pathway compared to the direct inhibition of **renin** shown by drug 'X'.
Question 262: Which statement best describes the relationship between drug potency and efficacy in dose-response curves?
- A. Drug C is as efficacious as drug D
- B. Drug D is more potent than drug C
- C. Drug B is the most efficacious (Correct Answer)
- D. Drug C is the most potent
Explanation: ***Drug B is the most efficacious*** - **Efficacy** refers to the **maximum effect (Emax)** a drug can produce, represented by the plateau height of the dose-response curve on the y-axis - **Drug B's curve reaches the highest point**, indicating it produces the greatest maximal blocking effect (~100 units) - **This makes Drug B the most efficacious drug** among the three, as it can produce the largest therapeutic response regardless of how much drug is given - Efficacy order: Drug B > Drug C > Drug D *Drug C is the most potent* - **Potency** refers to the amount of drug needed to produce a given effect, measured by **EC50** (the concentration producing 50% of maximal effect) - **The lower the EC50, the more potent the drug** (curve shifted to the left) - **Drug B has the lowest EC50** (its curve is furthest to the left), making it the most potent drug, not Drug C - Drug C requires a higher concentration than Drug B to achieve 50% effect, so it is less potent - Potency order: Drug B > Drug C > Drug D *Drug C is as efficacious as drug D* - **Drug C has higher efficacy than Drug D** because its curve reaches a higher plateau on the y-axis - Drug C achieves a maximal blocking effect of approximately 100 units, while Drug D reaches only approximately 75 units - **Different efficacy values** mean they are not equally efficacious - A drug's efficacy is independent of the dose required and depends only on the maximum achievable effect *Drug D is more potent than drug C* - **Drug C is actually more potent than Drug D**, not the reverse - Drug C's dose-response curve is **shifted to the left** of Drug D's curve, indicating a lower EC50 - This means **Drug C requires a lower concentration** to achieve 50% of its maximal effect compared to Drug D - The leftward shift indicates greater potency for Drug C
Question 263: Which drug elicits the following response on blood pressure and heart rate, as shown in the image?
- A. Epinephrine
- B. Dopamine
- C. Isoproterenol
- D. Norepinephrine (Correct Answer)
Explanation: ***Norepinephrine*** - Norepinephrine is a potent agonist at **α1** and **β1** receptors with minimal **β2** activity. The strong **α1** stimulation causes intense vasoconstriction, leading to a marked increase in systolic, diastolic, and mean arterial pressure, as seen in the graph. - Although norepinephrine directly stimulates the heart via **β1** receptors, the significant rise in blood pressure activates the **baroreceptor reflex**. This reflex increases vagal tone, which overrides the direct chronotropic effect and results in a net decrease in heart rate (reflex bradycardia). *Isoproterenol* - Isoproterenol is a non-selective **β-agonist** (**β1** and **β2**) and lacks **α-agonist** effects. It would cause a significant increase in heart rate (**β1** effect). - Its potent **β2** receptor stimulation leads to vasodilation and a *decrease* in diastolic and mean arterial pressure, which is the opposite of the response shown. *Epinephrine* - Epinephrine stimulates **α1**, **β1**, and **β2** receptors. At typical doses, the direct **β1** effect increases the heart rate, and the **β2** effect partially counteracts **α1**-mediated vasoconstriction, leading to a smaller rise in diastolic pressure. - The pronounced reflex bradycardia and significant increase in both systolic and diastolic pressure are more characteristic of norepinephrine's lack of **β2** agonism. *Dopamine* - Dopamine's effects are dose-dependent. At pressor doses (high doses) that stimulate **α1** receptors to increase blood pressure, there is also significant **β1** receptor stimulation. - The concurrent **β1** stimulation typically causes tachycardia or prevents significant reflex bradycardia, which is inconsistent with the graph showing a decreased heart rate.
Question 264: A female patient complains of swelling and pain in her great toe. Her uric acid level is found to be high. A drug that reduces uric acid levels is prescribed. Which of the following enzymes should the drug inhibit?
- A. Lysyl oxidase
- B. Xanthine oxidase (Correct Answer)
- C. Homogentisate oxidase
- D. Urease
Explanation: ***Xanthine oxidase*** - **Xanthine oxidase** catalyzes the conversion of hypoxanthine to xanthine and xanthine to uric acid in the purine degradation pathway - **Xanthine oxidase inhibitors** (allopurinol, febuxostat) are the mainstay drugs for chronic management of hyperuricemia and gout - By inhibiting this enzyme, these drugs reduce uric acid production, lowering serum uric acid levels and preventing crystal deposition in joints - The clinical presentation of **podagra** (acute pain and swelling of the great toe) with elevated uric acid is classic for **acute gouty arthritis** *Lysyl oxidase* - Involved in cross-linking collagen and elastin in connective tissue formation - Not related to purine metabolism or uric acid synthesis - Inhibition would affect collagen strength, not uric acid levels *Homogentisate oxidase* - Enzyme in the tyrosine degradation pathway - Deficiency causes alkaptonuria (accumulation of homogentisic acid) - Not involved in purine metabolism *Urease* - Bacterial enzyme that hydrolyzes urea to ammonia and carbon dioxide - Found in bacteria like *Helicobacter pylori* and *Proteus* species - Not involved in human uric acid synthesis or metabolism
Question 265: Which of the following drugs increases uric acid in urine?
- A. Allopurinol
- B. Probenecid (Correct Answer)
- C. Colchicine
- D. Febuxostat
Explanation: ***Probenecid***- This drug is a **uricosuric agent** that works by inhibiting the reabsorption of urate at the **proximal convoluted tubule** of the kidney.- By blocking reabsorption, **probenecid** promotes the excretion of uric acid into the urine, thereby reducing serum uric acid levels.*Colchicine*- *Colchicine* is primarily used for the management of **acute gout flares** and works by inhibiting neutrophil migration and subsequent inflammatory responses.- It does **not** significantly alter the renal handling of uric acid; therefore, it does not increase uric acid excretion in the urine.*Febuxostat*- *Febuxostat* is a **non-purine selective inhibitor of xanthine oxidase**, an enzyme required for uric acid synthesis.- Its mechanism is to **decrease the production** of uric acid by the body, thus lowering serum levels, rather than promoting its excretion in the urine.*Allopurinol*- *Allopurinol* is a **purine analog and a xanthine oxidase inhibitor** used for the prophylactic management of chronic gout.- Like Febuxostat, it acts to **decrease the synthesis** (production) of uric acid, contrasting with uricosuric agents which increase excretion.
Question 266: The most appropriate description of the vasomotor reversal of Dale is that
- A. Repeated administration of ephedrine decreases its effect on blood pressure
- B. An increase in pulse pressure is produced by the intravenous administration of isoprenaline
- C. A patient pretreated with phentolamine develops severe hypotension on the administration of adrenaline (Correct Answer)
- D. High dose of acetylcholine after alpha blockade produces vasomotor reversal
Explanation: ***A patient pretreated with phentolamine develops severe hypotension on the administration of adrenaline***%@%@%@%@In the **vasomotor reversal of Dale**, the typical pressor (vasoconstrictor) response of **adrenaline** is reversed to a depressor (vasodilator) response after the **alpha-receptors** have been non-selectively blocked.%@%@%@%@**Phentolamine** (an alpha-blocker) abolishes the alpha-1 mediated vasoconstriction, thus unmasking the predominant **beta-2 mediated vasodilation** effect of adrenaline, leading to **hypotension**.%@%@*Repeated administration of ephedrine decreases its effect on blood pressure*%@%@This describes **tachyphylaxis**, a rapid decrease in response to a drug following repeated administration over a short period.%@%@**Ephedrine** is an indirect sympathomimetic whose reduced effect is due to the rapid depletion of stored **norepinephrine** from the nerve terminals it acts upon.%@%@*High dose of acetylcholine after*%@%@The reversal of Dale is fundamentally an interaction within the **adrenergic system** (alpha and beta receptors) and requires an alpha-receptor blocker.%@%@**Acetylcholine** is the primary neurotransmitter of the **cholinergic system**, and its effects or paradoxical reversal effects do not define the vasomotor reversal of adrenaline.%@%@*An increase in pulse pressure is produced by the intravenous administration of isoprenaline*%@%@This is the expected, direct pharmacological effect of **isoprenaline** (isoproterenol), a potent non-selective **beta-agonist** (B1 and B2).%@%@Isoprenaline increases pulse pressure by significantly increasing cardiac output (B1) and causing marked peripheral vasodilation (B2), but this does not involve the required alpha-blockade and subsequent drug reversal.