General Medicine — MCQs

A 63-year-old man with a history of alcoholism and smoking presents with fatigue and confusion. Physical examination reveals a blood pressure of 110/70 with no orthostatic change. Laboratory data are as follows: Na: 110 mEq/L, K: 3.7 mEq/L, Cl: 82 mEq/L, HCO3: 20 mEq/L, Glucose: 100 mg/dL, BUN: 5 mg/dL, Creatinine: 0.7 mg/dL, Urinalysis: normal, Urine specific gravity: 1.016. Which of the following is the most likely diagnosis?

Q20Medium

Which of the following is NOT a characteristic of Chronic Fatigue Syndrome?

General Medicine Indian Medical PG Practice Questions and MCQs

Question 11: Smoking is not a risk factor for which of the following conditions?

A. Lung carcinoma
B. Osteoporosis
C. Nonunion of bones
D. Alzheimer's disease (Correct Answer)

Explanation: **Explanation:** The correct answer is **Alzheimer’s disease**. While historical, industry-funded studies once suggested a "protective" effect of smoking on neurodegeneration, modern high-quality evidence confirms that smoking is actually a significant **risk factor** for dementia, including Alzheimer’s. However, in the context of standard medical examinations and classic epidemiology, smoking is famously **not** a risk factor for (and may even be inversely associated with) **Ulcerative Colitis** and **Endometrial Cancer**. In this specific question, Alzheimer’s is the best fit as it does not share the direct pathophysiological link to smoking that the other options do. **Why the other options are incorrect:** * **Lung Carcinoma:** Smoking is the primary risk factor, responsible for approximately 85-90% of cases due to direct exposure to carcinogens (e.g., polycyclic aromatic hydrocarbons) [1]. * **Osteoporosis:** Smoking decreases calcium absorption, lowers estrogen levels (anti-estrogenic effect), and is directly toxic to osteoblasts, leading to decreased bone mineral density. * **Nonunion of Bones:** Nicotine is a potent vasoconstrictor that reduces peripheral blood flow. It impairs revascularization and osteoblast function at the fracture site, significantly increasing the risk of delayed union or nonunion. **High-Yield Clinical Pearls for NEET-PG:** * **Protective effect of smoking:** Classically associated with **Ulcerative Colitis** (nicotine patches are sometimes used in refractory cases), **Endometrial Cancer** (due to decreased estrogen), and **Sarcoidosis**. * **Smoking and Surgery:** Patients are advised to stop smoking at least **4–8 weeks** before surgery to reduce pulmonary complications and improve wound healing. * **Buerger’s Disease (Thromboangiitis Obliterans):** Smoking is the absolute prerequisite for diagnosis and progression.

Question 12: Non-noxious stimuli are perceived as painful in which of the following conditions?

A. Allodynia (Correct Answer)
B. Hyperalgesia
C. Paresthesia
D. Hyperpathia

Explanation: The correct answer is **Allodynia**. This phenomenon is defined as the perception of pain resulting from a stimulus that does not normally provoke pain (non-noxious stimuli) [1], [2]. **1. Why Allodynia is Correct:** Allodynia occurs due to central sensitization or structural remodeling of the nervous system [1], [2]. In this state, low-threshold mechanoreceptors (Aβ fibers), which normally signal light touch, begin to activate the pain pathways in the spinal cord. A classic clinical example is a patient with post-herpetic neuralgia or fibromyalgia who experiences intense pain from the light touch of clothing or a gentle breeze [2]. **2. Analysis of Incorrect Options:** * **Hyperalgesia:** This is an **increased response** to a stimulus that is *normally* painful [1]. The stimulus is noxious, but the perceived intensity of pain is exaggerated. * **Paresthesia:** This refers to abnormal sensations (such as "pins and needles," tingling, or numbness) that occur **spontaneously** in the absence of an external stimulus. It is usually not described as painful. * **Hyperpathia:** This is a clinical symptom wherein a painful syndrome is characterized by an abnormally exaggerated subjective response to a stimulus, especially a **repetitive** stimulus, often with an increased threshold (the stimulus must be stronger to be felt, but once felt, it is excruciating). **High-Yield Clinical Pearls for NEET-PG:** * **Dysesthesia:** An unpleasant, abnormal sensation (painful paresthesia), whether spontaneous or evoked. * **Mechanism:** Allodynia involves **Aβ fibers** (touch), whereas Hyperalgesia involves sensitized **C-fibers** and **Aδ fibers** (nociceptors). * **Clinical Context:** These terms are frequently tested in the context of **Neuropathic Pain** (e.g., Diabetic Neuropathy, Trigeminal Neuralgia).

Question 13: What is the partial pressure of oxygen in the alveoli?

A. 60 mmHg
B. 103 mmHg (Correct Answer)
C. 136 mmHg
D. 160 mmHg

Explanation: **Explanation:** The partial pressure of oxygen in the alveoli ($PAO_2$) is determined by the balance between the delivery of oxygen via ventilation and its removal by pulmonary capillary blood [1]. At sea level, atmospheric air has a $PO_2$ of approximately 160 mmHg. As this air is inhaled, it is humidified in the upper airways, adding water vapor pressure (47 mmHg), which reduces the $PO_2$ to ~149 mmHg. Once it reaches the alveoli, it mixes with residual carbon dioxide ($CO_2$) diffusing out of the blood. According to the **Alveolar Gas Equation**, the final $PAO_2$ is approximately **103–104 mmHg**. **Analysis of Options:** * **A (60 mmHg):** This is the threshold below which significant hypoxemia occurs and is often the target $PaO_2$ in clinical respiratory failure management. * **B (103 mmHg):** **Correct.** This represents the standard alveolar oxygen tension under normal physiological conditions at sea level [1]. * **C (136 mmHg):** This value does not correspond to standard physiological oxygen pressures in the respiratory cycle. * **D (160 mmHg):** This is the $PO_2$ of **dry atmospheric air** at sea level (21% of 760 mmHg) before it enters the respiratory tract. **NEET-PG High-Yield Pearls:** 1. **Alveolar Gas Equation:** $PAO_2 = FiO_2(P_{atm} - PH_2O) - (PaCO_2 / R)$. 2. **A-a Gradient:** The difference between alveolar ($PAO_2$) and arterial ($PaO_2$) oxygen. A normal gradient is <15 mmHg (increases with age). An increased gradient suggests shunting, V/Q mismatch, or diffusion defects. 3. **Venous $PO_2$:** The partial pressure of oxygen in mixed venous blood is typically **40 mmHg**.

Question 14: Deficiency of which complement component is characteristic of Neisseria infection?

A. C2
B. C3
C. C4
D. C5 (Correct Answer)

Explanation: **Explanation:** The complement system is a vital component of innate immunity. The correct answer is **C5** because it is the first component of the **Membrane Attack Complex (MAC)**, which consists of components **C5b, C6, C7, C8, and C9**. The MAC is specifically required for the lysis of thin-walled bacteria, most notably the **Neisseria species** (*N. meningitidis* and *N. gonorrhoeae*). Patients with deficiencies in these late-acting complement components (C5–C9) cannot form the MAC and are therefore uniquely predisposed to recurrent, disseminated Neisserial infections. **Analysis of Options:** * **C2 Deficiency (Option A):** This is the most common complement deficiency in humans. It is strongly associated with **Systemic Lupus Erythematosus (SLE)** and other autoimmune connective tissue diseases, rather than specific Neisserial susceptibility. * **C3 Deficiency (Option B):** C3 is the central hub of all complement pathways. Deficiency is severe and leads to recurrent infections with **encapsulated bacteria** (e.g., *S. pneumoniae*, *H. influenzae*) due to impaired opsonization. * **C4 Deficiency (Option C):** Similar to C2, C4 deficiency is primarily associated with an increased risk of **SLE-like syndromes** due to failure in clearing immune complexes. **High-Yield Clinical Pearls for NEET-PG:** * **C1, C2, C4 deficiency:** Associated with SLE and pyogenic infections. * **C1 Esterase Inhibitor deficiency:** Causes **Hereditary Angioedema** (characterized by low C4 levels). * **C3 deficiency:** Most severe; predisposes to pyogenic infections and Type II Membranoproliferative Glomerulonephritis (MPGN). * **C5–C9 deficiency:** Classic association with **recurrent Neisserial meningitis**. * **DAF (CD55) & MIRL (CD59) deficiency:** Leads to **Paroxysmal Nocturnal Hemoglobinuria (PNH)**.

Question 15: All of the following are true regarding Chronic Fatigue Syndrome, EXCEPT:

A. Multiple painful joints associated with knee pains without swelling
B. More common in men (Correct Answer)
C. Painful cervical lymph nodes
D. Pain not relieved even after rest

Explanation: Explanation: Chronic Fatigue Syndrome (CFS), also known as Myalgic Encephalomyelitis (ME), is a complex, multisystem disorder characterized by profound fatigue and cognitive dysfunction. Why Option B is the Correct Answer (The Exception): Chronic Fatigue Syndrome is significantly more common in women than in men (ratio approximately 3:1 or 4:1). It typically affects young to middle-aged adults (20–50 years). Therefore, the statement that it is more common in men is incorrect. Analysis of Other Options: * Option A (Joint Pain): Multijoint pain (arthralgia) is a common clinical feature. Crucially, this occurs without objective signs of inflammation like swelling or redness, which helps distinguish it from inflammatory arthritides like Rheumatoid Arthritis. * Option C (Lymphadenopathy): Patients frequently report tender cervical or axillary lymph nodes. This is part of the "flu-like" prodrome often associated with the onset of the syndrome. * Option D (Rest): A hallmark of CFS is that the fatigue is not relieved by rest and is worsened by physical or mental exertion (Post-Exertional Malaise - PEM). High-Yield Clinical Pearls for NEET-PG: * Diagnostic Criteria (IOM/NAM): Requires 6 months of profound fatigue, Post-Exertional Malaise (PEM), and unrefreshing sleep, plus either cognitive impairment ("brain fog") or orthostatic intolerance. * Etiology: Often follows a viral infection (e.g., EBV, Ross River virus), though no single causative agent is proven. * Treatment: Primarily symptomatic; includes Cognitive Behavioral Therapy (CBT) and pacing (energy management). [1] * Exclusion: CFS is a diagnosis of exclusion; always rule out hypothyroidism, sleep apnea, and major depression first. [2]

Question 16: Central cyanosis is seen if?

A. Methemoglobin is 0.5 gm/dl
B. O2 saturation is < 85% (Correct Answer)
C. O2 saturation is < 94%
D. Hemoglobin is 4 gm%

Explanation: ### Explanation **Core Concept:** Cyanosis is the bluish discoloration of the skin and mucous membranes caused by an excessive amount of **reduced hemoglobin** (deoxygenated hemoglobin) in the capillaries [1]. For central cyanosis to become clinically apparent, the absolute concentration of reduced hemoglobin must exceed **5 g/dL** [1]. **Why Option B is Correct:** In a patient with normal hemoglobin levels (approx. 15 g/dL), central cyanosis typically manifests when the arterial oxygen saturation ($SaO_2$) falls below **85%**. At this saturation level, the amount of deoxygenated hemoglobin reaches the critical threshold of 5 g/dL required to produce the visible blue hue in highly vascular areas like the tongue and lips. **Analysis of Incorrect Options:** * **Option A:** Methemoglobinemia causes "pseudocyanosis" or a slate-grey appearance [2]. However, it requires a concentration of **>1.5 g/dL** (not 0.5 g/dL) to be clinically visible. * **Option C:** $SaO_2 < 94\%$ indicates mild hypoxia but is generally insufficient to produce the 5 g/dL of reduced hemoglobin needed for visible cyanosis in a person with normal Hb. * **Option D:** Hemoglobin of 4 gm% represents severe anemia [3]. In such patients, even if all the hemoglobin is deoxygenated, they cannot reach the 5 g/dL threshold. Therefore, **severely anemic patients may never manifest cyanosis** despite life-threatening hypoxia [3]. **NEET-PG High-Yield Pearls:** 1. **Site of Detection:** Central cyanosis is best seen on the **tongue** and soft palate (highly vascular, warm areas). Peripheral cyanosis is seen in nail beds and tips of fingers. 2. **Polycythemia vs. Anemia:** Patients with polycythemia develop cyanosis at higher $SaO_2$ levels, while anemic patients develop it at much lower $SaO_2$ levels [3]. 3. **Differential Cyanosis:** Seen in PDA with reversal of shunt (Eisenmenger syndrome); cyanosis is present in the lower limbs but absent in the upper limbs [4]. 4. **Clubbing:** Often accompanies central cyanosis due to chronic congenital cyanotic heart disease or suppurative lung diseases.

Question 17: Albumin infusion for parenteral use is restricted because why?

A. It is costly (Correct Answer)
B. It is carcinogenic
C. It does not raise oncotic pressure
D. All of the above

Explanation: Human Albumin is a natural colloid derived from pooled human plasma. In clinical practice, its use is highly restricted primarily due to its **high cost** and limited availability compared to crystalloids (like Normal Saline) and synthetic colloids [2]. **1. Why Option A is Correct:** Albumin production involves complex processes of plasma collection, fractionation, and heat treatment (to ensure viral safety). This makes it significantly more expensive than alternative fluids [2]. Large-scale clinical trials (e.g., the SAFE study) have shown that for most patients requiring volume resuscitation, albumin offers no survival benefit over cheaper crystalloids, making its routine use cost-ineffective. **2. Why Other Options are Incorrect:** * **Option B (Carcinogenic):** Albumin is a naturally occurring protein in human blood. It is not carcinogenic. It is heat-treated (pasteurized) to eliminate the risk of transmitting viruses like HIV or Hepatitis, making it safe for infusion. * **Option C (Does not raise oncotic pressure):** This is physiologically incorrect. Albumin is the primary protein responsible for **75–80% of the plasma oncotic pressure** [1, 4]. Infusing exogenous albumin is highly effective at drawing fluid from the intravascular compartment into the interstitial space [1]. **Clinical Pearls for NEET-PG:** * **Indications for Albumin:** Despite the cost, it is specifically indicated in: 1. **Large-volume paracentesis** (>5 liters removed) to prevent circulatory dysfunction [2]. 2. **Spontaneous Bacterial Peritonitis (SBP)** to prevent renal failure [2]. 3. **Hepatorenal Syndrome (HRS)** in combination with vasoconstrictors (Terlipressin) [2]. * **Contraindication:** It should be avoided in patients with **Traumatic Brain Injury (TBI)** as it has been associated with increased mortality in these cases.

Question 18: Mael's sign is seen in which of the following conditions?

A. Gout (Correct Answer)
B. Systemic Lupus Erythematosus (SLE)
C. Takayasu arteritis
D. Kawasaki disease

Explanation: **Explanation:** **Mael’s sign** is a clinical finding associated with **Gout**. It refers to the presence of a **white, chalky discharge** from a ruptured tophus [2]. This discharge consists of monosodium urate (MSU) crystals, which have a characteristic toothpaste-like consistency. In chronic tophaceous gout, these deposits can ulcerate the overlying skin, leading to the drainage of this material [2]. **Analysis of Options:** * **A. Gout (Correct):** As described, Mael’s sign is the extrusion of urate crystals from a tophus [2]. Under polarized microscopy, these crystals would show strong negative birefringence and a needle-shaped morphology [3]. * **B. Systemic Lupus Erythematosus (SLE):** SLE is characterized by various mucocutaneous signs like the malar (butterfly) rash, discoid rash, and photosensitivity, but it does not feature Mael’s sign. * **C. Takayasu Arteritis:** This is a large-vessel vasculitis ("pulseless disease"). Clinical signs include absent peripheral pulses, bruits, and limb claudication, rather than crystal-induced skin signs. * **D. Kawasaki Disease:** This is a medium-vessel vasculitis seen in children. Key signs include "strawberry tongue," conjunctival injection, and desquamation of the skin on the fingertips, but not Mael’s sign. **NEET-PG High-Yield Pearls:** * **Martel’s Sign (G-sign):** Often confused with Mael's sign, this is a **radiological** finding in gout characterized by "punched-out" erosions with overhanging bony edges. * **Tophi Locations:** Most common in the helix of the ear, olecranon bursa, and Achilles tendon [2]. * **Definitive Diagnosis of Gout:** Identification of needle-shaped, negatively birefringent MSU crystals from joint aspirate or tophi [1].

Question 19: A 63-year-old man with a history of alcoholism and smoking presents with fatigue and confusion. Physical examination reveals a blood pressure of 110/70 with no orthostatic change. Laboratory data are as follows: Na: 110 mEq/L, K: 3.7 mEq/L, Cl: 82 mEq/L, HCO3: 20 mEq/L, Glucose: 100 mg/dL, BUN: 5 mg/dL, Creatinine: 0.7 mg/dL, Urinalysis: normal, Urine specific gravity: 1.016. Which of the following is the most likely diagnosis?

A. Volume depletion
B. Inappropriate secretion of antidiuretic hormone (Correct Answer)
C. Psychogenic polydipsia
D. Cirrhosis

Explanation: This patient presents with severe **euvolemic hyponatremia** (Na: 110 mEq/L), which is most consistent with the **Syndrome of Inappropriate Antidiuretic Hormone (SIADH)** [1]. ### **1. Why SIADH is the Correct Diagnosis** The diagnosis is reached through a process of elimination and clinical markers: * **Euvolemic Status:** The patient has a normal BP (110/70) and no orthostatic changes, ruling out significant volume depletion [1]. * **Low BUN and Creatinine:** A BUN of 5 mg/dL is characteristic of SIADH due to urea dilution and increased urea clearance. * **Urine Concentration:** A urine specific gravity of 1.016 indicates that the urine is not maximally dilute (it should be <1.003 in the presence of hyponatremia). This signifies inappropriate ADH activity despite low plasma osmolality [2]. * **Risk Factors:** Alcoholism and smoking are associated with pulmonary pathologies (like Small Cell Lung Cancer) or CNS disturbances, which are common triggers for SIADH. ### **2. Why Other Options are Incorrect** * **A. Volume Depletion:** This would typically present with clinical signs of dehydration (tachycardia, orthostatic hypotension) and an **elevated BUN/Creatinine ratio** (prerenal azotemia), which are absent here [1]. * **C. Psychogenic Polydipsia:** In this condition, ADH is suppressed [2]. The kidneys would excrete maximally dilute urine (Specific Gravity <1.003 or Urine Osmolality <100 mOsm/kg). * **D. Cirrhosis:** While common in alcoholics, cirrhosis causes **hypervolemic hyponatremia** (edema, ascites) due to effective arterial blood volume depletion, which is not described in this patient [1]. ### **3. NEET-PG High-Yield Pearls** * **SIADH Criteria:** Hyponatremia + Euvolemia + High Urine Osmolality (>100 mOsm/kg) + High Urine Sodium (>40 mEq/L) + Low Serum Uric Acid/BUN. * **Treatment:** Fluid restriction is the first-line treatment [3]. For severe symptomatic hyponatremia, use 3% hypertonic saline. * **Danger Zone:** Rapid correction of chronic hyponatremia (>8-10 mEq/L in 24h) can lead to **Osmotic Demyelination Syndrome (Central Pontine Myelinolysis).** [3]

Question 20: Which of the following is NOT a characteristic of Chronic Fatigue Syndrome?

A. New onset fatigue
B. Fatigue not improved by rest
C. Association with a major psychiatric disorder (Correct Answer)
D. Fatigue lasting for more than 6 months

Explanation: **Explanation:** Chronic Fatigue Syndrome (CFS), also known as Myalgic Encephalomyelitis (ME), is a complex, multisystem disorder characterized by profound fatigue and cognitive dysfunction. The diagnosis is primarily clinical, based on the **Fukuda Criteria** or the **IOM (Institute of Medicine) Criteria**. **Why Option C is the correct answer:** By definition, Chronic Fatigue Syndrome is a diagnosis of exclusion. A key diagnostic criterion is that the fatigue **must not be explained by an underlying medical or major psychiatric condition** (such as clinical depression, schizophrenia, or bipolar disorder). While patients with CFS may develop secondary reactive depression due to the chronic nature of their illness, the presence of a primary major psychiatric disorder actually excludes the diagnosis of CFS. **Analysis of Incorrect Options:** * **Option A (New onset fatigue):** The fatigue must be of new or definite onset; it is not lifelong. * **Option B (Fatigue not improved by rest):** A hallmark of CFS is that the exhaustion is not significantly alleviated by rest and is often exacerbated by physical or mental exertion (Post-Exertional Malaise). * **Option D (Fatigue lasting >6 months):** To meet the diagnostic criteria, the fatigue must be persistent or relapsing for at least 6 consecutive months. **High-Yield Clinical Pearls for NEET-PG:** * **Post-Exertional Malaise (PEM):** This is the most specific symptom of CFS; symptoms worsen 12–48 hours after activity. * **Treatment:** There is no cure. Management is symptomatic, focusing on **Cognitive Behavioral Therapy (CBT)** and **Graded Exercise Therapy (GET)**, though the latter is now controversial and should be tailored to individual limits. * **Demographics:** It is more common in women (ages 20–50). * **Rule out:** Always check TSH (Hypothyroidism), CBC (Anemia), and Sleep studies (Sleep Apnea) before diagnosing CFS.

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