Metabolic Disorders — MCQs
A 70-year-old man with hypertension and hyperlipidemia has sudden right eye vision loss, described as a 'curtain coming down'. What is the most likely diagnosis?
Kayser-Fleischer ring is found in which layer of cornea?
A patient complained of gradual diminution of vision. On examination, the patient had dry eyes and a rough corneal surface. What deficiency is most likely causing these manifestations?
In the context of homocystinuria, which direction does the lens typically subluxate?
A 60-year-old man presents with choreoathetosis. On examination, Kayser-Fleischer rings are seen in the cornea. What is the initial treatment of choice for this condition?
Which of the following conditions is NOT associated with retinitis pigmentosa?
Which of the following are metabolic causes of splenic enlargement?
All are manifestation of dengue virus infection in eye except?
Treatment of choice for clinically significant macular edema in a diabetic is?
In primary open-angle glaucoma (POAG), which of the following findings is NOT typically seen?
Metabolic Disorders Indian Medical PG Practice Questions and MCQs
Question 1: A 70-year-old man with hypertension and hyperlipidemia has sudden right eye vision loss, described as a 'curtain coming down'. What is the most likely diagnosis?
- A. Amaurosis fugax
- B. Optic neuritis
- C. Retinal detachment (Correct Answer)
- D. Glaucoma
Explanation: ***Retinal detachment*** - The **classic "curtain coming down"** description is pathognomonic for retinal detachment, representing the progressive separation of the neurosensory retina from the retinal pigment epithelium. - Presents with **sudden, persistent vision loss** (not transient), often accompanied by **photopsia (flashes)** and **floaters** in the prodromal phase. - Risk factors include advanced age (vitreous degeneration), myopia, previous cataract surgery, and trauma. - This is an **ophthalmologic emergency** requiring urgent surgical intervention to prevent permanent vision loss. *Amaurosis fugax* - Describes **transient monocular vision loss** lasting seconds to minutes with **complete resolution**. - Caused by emboli from carotid atherosclerosis causing temporary retinal ischemia. - While the patient has vascular risk factors, the **persistent nature** of vision loss (described in present tense as "has vision loss") excludes this diagnosis. - Patients typically describe it as a "curtain that came down **and lifted**." *Optic neuritis* - Presents with **subacute, painful vision loss** developing over hours to days. - Associated with **pain on eye movement** and commonly linked to demyelinating diseases like multiple sclerosis. - The sudden "curtain" description and lack of pain make this diagnosis unlikely. *Glaucoma* - Acute angle-closure glaucoma can cause sudden vision loss but presents with **severe eye pain**, **red eye**, **halos around lights**, and a **mid-dilated fixed pupil**. - Chronic open-angle glaucoma causes **gradual peripheral vision loss** over months to years. - The "curtain coming down" description is not characteristic of either glaucoma type.
Question 2: Kayser-Fleischer ring is found in which layer of cornea?
- A. Endothelium
- B. Descemet's membrane (Correct Answer)
- C. Bowman's layer
- D. Corneal stroma
Explanation: ***Descemet's membrane*** - Kayser-Fleischer rings are caused by **copper deposition** at the periphery of the cornea, specifically within **Descemet's membrane**. - This membrane is located between the **corneal stroma** and the **endothelium**. *Bowman's layer* - Bowman's layer is a thin, acellular layer of the cornea that lies beneath the **corneal epithelium**. - While it plays a role in corneal integrity, it is not the site of **copper deposition** in Wilson's disease. *Corneal stroma* - The corneal stroma is the thickest layer of the cornea, composed primarily of **collagen fibrils**. - Although it contains most of the corneal mass, **copper deposition** in Kayser-Fleischer rings does not specifically occur within the main stromal layer. *Endothelium* - The corneal endothelium is the innermost layer of the cornea, responsible for maintaining **corneal deturgescence**. - While it is adjacent to Descemet's membrane, the copper rings are deposited in the membrane itself, not directly in the endothelial cell layer.
Question 3: A patient complained of gradual diminution of vision. On examination, the patient had dry eyes and a rough corneal surface. What deficiency is most likely causing these manifestations?
- A. Iron
- B. Protein
- C. Niacin
- D. Vitamin A (Correct Answer)
Explanation: ***Vitamin A*** - **Vitamin A deficiency** is a common cause of **xerophthalmia**, characterized by **dry eyes** (**xerosis conjunctivae**) and roughening of the **cornea** due to impaired mucin production [1]. In vitamin A deficiency, mucus-secreting cells are replaced by keratin-producing cells [2]. - Progression of ocular epithelial keratinization can lead to **Bitot's spots**, corneal ulceration, and ultimately **blindness** [1], [2]. *Iron* - **Iron deficiency** primarily leads to **iron-deficiency anemia**, causing fatigue, pallor, and weakness, but not directly ocular manifestations like dry eyes or rough cornea. - While severe anemia can cause some visual disturbances, it does not typically present with the specific **xerophthalmic** changes seen here. *Protein* - **Protein deficiency** can lead to conditions like **kwashiorkor** (edema, muscle wasting) or **marasmus** (severe wasting), which broadly impair health and immunity. - However, it does not directly cause the specific ocular signs of **dryness** and **corneal roughening** as a primary deficiency, though it can exacerbate other nutritional deficiencies. *Niacin* - **Niacin (Vitamin B3) deficiency** causes **pellagra**, characterized by the "3 Ds": **dermatitis**, **diarrhea**, and **dementia**. - Ocular symptoms are not a common or primary feature of niacin deficiency; it does not cause **dry eyes** or **corneal roughening**.
Question 4: In the context of homocystinuria, which direction does the lens typically subluxate?
- A. Inferotemporal
- B. Inferonasal (Correct Answer)
- C. Superonasal
- D. Superotemporal
Explanation: ***Inferonasal*** - In **homocystinuria**, the **ectopia lentis** (lens subluxation) often occurs due to weakening of the **zonular fibers**. - The classic direction for lens subluxation in homocystinuria is **inferior and nasal**. *Inferotemporal* - While lens subluxation can occur in various directions, **inferotemporal** is not the classic or most common presentation in homocystinuria. - This direction is less specific and does not strongly point to homocystinuria as the underlying cause. *Superonasal* - **Superonasal** dislocation of the lens is more characteristic of **Marfan syndrome**, which is important to differentiate from homocystinuria. - This direction helps distinguish different causes of lens ectopia. *Superotemporal* - **Superotemporal** lens subluxation is the hallmark of **Marfan syndrome**, a genetic connective tissue disorder. - This specific finding is crucial for differential diagnosis in patients presenting with lens ectopia.
Question 5: A 60-year-old man presents with choreoathetosis. On examination, Kayser-Fleischer rings are seen in the cornea. What is the initial treatment of choice for this condition?
- A. Penicillamine (a chelating agent)
- B. Zinc (reduces copper absorption) (Correct Answer)
- C. Trientine (a chelating agent)
- D. Pyridoxine (Vitamin B6)
Explanation: ***Zinc (reduces copper absorption)*** - **Zinc** is often the initial treatment of choice, especially in asymptomatic or mildly symptomatic patients, as it works by inducing **metallothionein** in the intestinal cells, which binds copper and prevents its absorption. - This reduces the body's copper load without causing potential side effects associated with intense chelation, making it a safer first-line option. *Penicillamine (a chelating agent)* - **D-penicillamine** is a chelating agent that binds to copper and promotes its excretion; however, it has significant side effects such as **nephrotoxicity** and **bone marrow suppression**. - Its use is generally reserved for patients who cannot tolerate zinc or require more aggressive copper removal. *Trientine (a chelating agent)* - **Trientine** is another copper chelating agent, often preferred over penicillamine due to its better side-effect profile but still considered a more aggressive treatment than zinc. - It is typically used for patients who are unable to tolerate penicillamine or require chelation. *Pyridoxine (Vitamin B6)* - **Pyridoxine (Vitamin B6)** is not a direct treatment for Wilson's disease. - It's mainly used to prevent or treat peripheral neuropathy in patients receiving **isoniazid** or **penicillamine**, as penicillamine can sometimes interfere with B6 metabolism [1].
Question 6: Which of the following conditions is NOT associated with retinitis pigmentosa?
- A. Kearns-Sayre Syndrome
- B. Usher Syndrome
- C. Marfan's Syndrome (Correct Answer)
- D. Bassen-Kornzweig Syndrome
Explanation: ***Marfan's Syndrome*** - Marfan's Syndrome is primarily a **connective tissue disorder** affecting the **cardiovascular system**, **skeletal system**, and **eyes** (e.g., lens dislocation). - It is **not directly associated** with the progressive **photoreceptor degeneration** characteristic of retinitis pigmentosa. *Usher Syndrome* - Usher Syndrome is a **recessive genetic disorder** characterized by **hearing loss** and progressive **vision loss** due to retinitis pigmentosa. - It involves both **auditory** and **visual impairments**, directly linking it to retinitis pigmentosa. *Kearns-Sayre Syndrome* - Kearns-Sayre Syndrome is a **mitochondrial disorder** that includes **external ophthalmoplegia**, **cardiac conduction defects**, and often **pigmentary retinopathy** resembling retinitis pigmentosa. - The retinal degeneration in Kearns-Sayre syndrome is a **hallmark ocular manifestation**. *Bassen-Kornzweig Syndrome* - Also known as **abetalipoproteinemia**, this is a rare **autosomal recessive disorder** characterized by the inability to absorb **dietary fats and fat-soluble vitamins** (especially vitamin A). - Severe **vitamin A deficiency** can lead to atypical retinitis pigmentosa-like retinal degeneration and **night blindness**.
Question 7: Which of the following are metabolic causes of splenic enlargement?
- A. Porphyria and Felty's syndrome
- B. Amyloid and Gaucher's disease (Correct Answer)
- C. Myelofibrosis and Weil's disease
- D. Rickets and Still's disease
Explanation: ***Amyloid and Gaucher's disease*** - **Amyloidosis** is characterized by the extracellular deposition of insoluble abnormal **fibrillar proteins (amyloid)** in various organs, including the spleen, leading to its enlargement [2]. - **Gaucher's disease** is a **lysosomal storage disorder** where macrophages accumulate **glucocerebroside**, particularly in the spleen, liver, and bone marrow, causing significant **splenomegaly** [1]. *Porphyria and Felty's syndrome* - **Porphyria** is a group of metabolic disorders primarily affecting **heme synthesis**, leading to diverse symptoms, but **splenomegaly** is not a primary or prominent feature. - **Felty's syndrome** is a severe manifestation of **rheumatoid arthritis** combined with **splenomegaly** and **neutrogenia**, and while it causes splenomegaly, it's an **immune-mediated** condition rather than a primary metabolic storage disease. *Myelofibrosis and Weil's disease* - **Myelofibrosis** is a **myeloproliferative neoplasm** characterized by bone marrow fibrosis, extramedullary hematopoiesis (often in the spleen), and **splenomegaly**, but it is not a metabolic disorder [3]. - **Weil's disease** is a severe form of **leptospirosis**, an **infectious disease** that can cause hepatosplenomegaly, but it is not a metabolic cause. *Rickets and Still's disease* - **Rickets** is a bone disease caused by a **vitamin D deficiency** leading to impaired bone mineralization, and it does not typically cause **splenomegaly**. - **Still's disease** (Systemic Juvenile Idiopathic Arthritis in children, or Adult-Onset Still's Disease) is an **inflammatory disorder** characterized by fever, rash, joint pain, and can cause **splenomegaly** as part of a systemic inflammatory response, not due to a metabolic storage issue. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 162-163. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 135-136. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 631-632.
Question 8: All are manifestation of dengue virus infection in eye except?
- A. Cataract (Correct Answer)
- B. Vitreous hemorrhage
- C. Maculopathy
- D. Optic neuritis
Explanation: ***Cataract*** - **Cataracts** are primarily associated with aging, congenital factors, trauma, or long-term steroid use, not directly with acute dengue virus infection. - While dengue can cause various ocular manifestations, the formation of cataracts is a **chronic process** that does not fit the typical acute or subacute presentation of dengue-related eye complications. *Vitreous hemorrhage* - **Vitreous hemorrhage** can occur in dengue due to associated **thrombocytopenia** and coagulation abnormalities, leading to bleeding in the eye. - Severe dengue can induce systemic vasculopathy and bleeding tendencies, which may manifest as intraocular hemorrhage. *Maculopathy* - **Dengue maculopathy** is a recognized complication, often presenting as macular edema, hemorrhage, or foveolitis, leading to visual impairment. - This is thought to be due to direct viral effects, immune-mediated responses, or vasculitis affecting the retinal microvasculature. *Optic neuritis* - **Optic neuritis** following dengue infection has been reported, characterized by inflammation of the optic nerve, causing acute vision loss. - This is considered to be an **immune-mediated post-infectious complication** rather than a direct viral cytopathic effect on the nerve.
Question 9: Treatment of choice for clinically significant macular edema in a diabetic is?
- A. Intravitreal anti-VEGF injections (Correct Answer)
- B. Control of Diabetes
- C. Panretinal Photocoagulation
- D. Focal Photocoagulation
Explanation: ***Intravitreal anti-VEGF injections*** - **Anti-VEGF agents** (e.g., ranibizumab, aflibercept) are the first-line treatment for **clinically significant diabetic macular edema (DME)** as they effectively reduce vascular leakage and improve vision. - They target **vascular endothelial growth factor (VEGF)**, a key mediator of increased vascular permeability and neovascularization in diabetic retinopathy. *Control of Diabetes* - While essential for preventing the **progression of diabetic retinopathy** and overall health, it is not the primary direct treatment for *existing* clinically significant macular edema. - Good glycemic control can reduce the *risk* of developing DME but does not acutely resolve established edema. *Panretinal Photocoagulation* - **Panretinal photocoagulation (PRP)** is primarily used for **proliferative diabetic retinopathy (PDR)** to ablate ischemic retina and reduce neovascularization. - It is not the treatment of choice for macular edema, as it can sometimes worsen macular function and visual acuity due to treatment-induced damage. *Focal Photocoagulation* - **Focal laser photocoagulation** was historically used for DME, targeting discrete leaking microaneurysms. - While effective for specific focal leakage, it has largely been superseded by **anti-VEGF injections** due to their superior efficacy in diffuse edema and better visual outcomes, especially when edema involves the fovea.
Question 10: In primary open-angle glaucoma (POAG), which of the following findings is NOT typically seen?
- A. Bayoneting sign (arteriovenous crossing changes)
- B. Peripapillary atrophy
- C. Horizontal cupping of the optic disc
- D. Macular edema (Correct Answer)
Explanation: ***Macular edema*** - **Macular edema** is characterized by fluid accumulation in the fovea or retina, causing blurry vision and metamorphopsia. - While it can occur in conditions like **diabetic retinopathy** or **uveitis**, it is **not a typical finding in POAG**, which primarily affects the optic nerve. *Horizontal cupping of the optic disc* - **Horizontal cupping** (or vertical elongation of the optic cup) is a common sign of **glaucomatous damage**, reflecting the loss of retinal ganglion cells. - This morphological change suggests the progression of optic nerve atrophy. *Bayoneting sign (arteriovenous crossing changes)* - The **bayoneting sign**, where blood vessels appear to dip below the optic disc margin and then sharply bend, is a feature of **advanced glaucomatous cupping**. - It indicates significant loss of optic nerve tissue and is often associated with deeply excavated optic discs. *Peripapillary atrophy* - **Peripapillary atrophy** (PPA) refers to areas of RPE and choroidal atrophy surrounding the optic disc, commonly seen in glaucoma. - While its presence and extent may correlate with **glaucoma severity**, it is a recognized clinical feature of the disease.
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