Nephrology — MCQs

Nephrology Indian Medical PG Practice Questions and MCQs

Question 801: Hyperkalemia aciduria is seen in

A. Type I Renal Tubular Acidosis
B. Type IV Renal Tubular Acidosis (Correct Answer)
C. Sigmoidocolostomy procedure
D. Type II Renal Tubular Acidosis

Explanation: Type IV Renal Tubular Acidosis - This condition is characterized by **hyperkalemia** and **aciduria**, often due to a deficiency in aldosterone or a renal tubular insensitivity to aldosterone [1]. - The impaired aldosterone action leads to reduced potassium excretion and decreased ammonium production, both contributing to **hyperkalemia** and metabolic acidosis [1]. *Type I Renal Tubular Acidosis* - Type I RTA (distal RTA) is characterized by a defect in acid secretion in the distal tubule, leading to **hypokalemia** and metabolic acidosis with persistently high urine pH [2]. - Patients typically excrete an alkaline urine despite systemic acidosis, contrasting with the aciduria seen with hyperkalemia [2]. *Sigmoidocolostomy procedure* - A sigmoidocolostomy can lead to **hyperchloremic metabolic acidosis** due to the reabsorption of chloride and excretion of bicarbonate by the colonic mucosa. - However, it typically causes **hypokalemia** as potassium is secreted into the colonic lumen from the blood. *Type II Renal Tubular Acidosis* - Type II RTA (proximal RTA) involves a defect in bicarbonate reabsorption in the proximal tubule, resulting in **hypokalemia** and metabolic acidosis. - The kidney's ability to acidify urine is still largely intact in the distal nephron once the bicarbonate buffer system is overwhelmed.

Question 802: A diabetic patient presents with hyperkalemia and urinary pH < 5.5. What is the MOST likely underlying cause?

A. Uremia
B. Primary hyperaldosteronism
C. Type IV RTA (Correct Answer)
D. Type I Renal tubular acidosis

Explanation: ***Type IV RTA*** - Patients with **diabetes mellitus** frequently develop **hyporeninemic hypoaldosteronism**, leading to Type IV RTA [1]. - This condition is characterized by **hyperkalemia** and **acidosis** with a paradoxically low urinary pH (typically < 5.5). *Uremia* - **Uremia** can cause hyperkalemia and acidosis, but it is a broader term for severe kidney failure and not the most specific underlying cause for the given urinary findings. - While patients with uremia can have aciduria, the combination of **diabetic hyperkalemia** and acid urine points more directly to a specific tubular defect. *Primary hyperaldosteronism* - **Primary hyperaldosteronism** is characterized by **hypertension**, **hypokalemia**, and metabolic alkalosis, which is the opposite of the patient's presentation [1]. - This condition involves excessive aldosterone production, leading to increased potassium excretion [1]. *Type I Renal tubular acidosis* - **Type I RTA** (distal RTA) is characterized by the inability to acidify urine, resulting in a **urinary pH > 5.5** despite systemic acidosis [1]. - While it can cause hypokalemia (due to increased distal K+ secretion) and acidosis, the elevated urinary pH is a key differentiating factor from this patient's presentation [1].

Question 803: Which of the following is not an absolute indication for hemodialysis?

A. GI bleeding (Correct Answer)
B. Convulsions
C. Pericarditis
D. Hyperkalemia of 6.5 mEq/L

Explanation: ***GI bleeding*** - While patients on dialysis may experience gastrointestinal bleeding, it is not a direct indication for initiating or continuing **hemodialysis**. - **GI bleeding** in end-stage renal disease (ESRD) patients can be due to various causes and requires specific management of the bleeding itself, not necessarily an alteration in dialysis prescription. *Convulsions* - **Convulsions** in patients with renal failure, especially due to uremia, are a severe manifestation of **uremic encephalopathy**. - This is an absolute indication for **hemodialysis** as it rapidly removes uremic toxins causing central nervous system dysfunction. *Pericarditis* - **Uremic pericarditis**, characterized by inflammation of the pericardium due to accumulation of uremic toxins, is a serious complication of renal failure. - It is an absolute indication for **hemodialysis** to prevent further cardiac complications like cardiac tamponade. *Hyperkalemia of 6.5 mEq/L* - Severe **hyperkalemia** (typically > 6.0-6.5 mEq/L) is a life-threatening electrolyte imbalance that can cause cardiac arrhythmias. - **Hemodialysis** is highly effective in rapidly removing potassium from the body and is an absolute indication, especially if unresponsive to other medical therapies.

Question 804: What is the recommended rate of correction for sodium deficit in patients with chronic hyponatremia?

A. 0.5 mmol/hour (Correct Answer)
B. 1 mmol/hour
C. 1.5 mmol/hour
D. 2.0 mmol/hour

Explanation: ***0.5 mmol/hour*** [1] - This rate of correction is recommended to avoid **osmotic demyelination syndrome (ODS)**, also known as central pontine myelinolysis [1]. - The aim is to correct the sodium deficit gradually, with a maximum increase not exceeding **8-10 mmol/L in any 24-hour period** [1]. *1 mmol/hour* - This rate is generally considered too rapid for chronic hyponatremia and increases the risk of **osmotic demyelination syndrome**. - While acceptable in some acute severe cases, it is typically avoided in chronic settings where the brain has adapted to lower osmolality. *1.5 mmol/hour* - This rate would lead to an even faster correction of sodium, significantly elevating the risk of **osmotic demyelination syndrome**. - It would result in a correction of 36 mmol/L over 24 hours, far exceeding the recommended daily limit of 8-10 mmol/L. *2.0 mmol/hour* - Such a rapid correction rate is highly dangerous and almost guarantees the development of **osmotic demyelination syndrome**. - This aggressive correction would lead to severe brain injury due to rapid osmotic shifts.

Question 805: Calciphylaxis is a severe life-threatening condition. Which of the following is most commonly associated with it?

A. Parathyroidectomy
B. Medullary carcinoma thyroid
C. Hyperthyroidism
D. End stage Renal disease (Correct Answer)

Explanation: ***End stage Renal disease*** - Calciphylaxis frequently occurs in patients with **end-stage renal disease**, primarily associated with **secondary hyperparathyroidism** [1] and **calcium-phosphate imbalance**. - It leads to **cutaneous ischemia** and necrosis, often requiring aggressive management due to its high **mortality rate**. *Parathyroidectomy* - While parathyroidectomy may affect calcium levels, it is not directly linked to calciphylaxis. - Calciphylaxis more commonly develops due to underlying **chronic renal failure** [1] rather than surgical interventions. *Hyperthyroidism* - Hyperthyroidism primarily causes symptoms related to metabolism, **thyroid hormone excess**, and does not lead to calciphylaxis. - There is no direct correlation between hyperthyroid states and the pathophysiology of calciphylaxis. *Medullary carcinoma thyroid* - This condition involves **medullary thyroid carcinoma**, associated with calcitonin production and does not cause calciphylaxis. - Patients typically experience **thyroid-related symptoms** rather than the vascular complications seen in calciphylaxis.

Question 806: Which of the following statements about Alport's syndrome is incorrect?

A. Nerve deafness
B. Glomerulonephritis
C. Autosomal dominant (Correct Answer)
D. X-linked

Explanation: ***Autosomal dominant*** - While there are rare autosomal dominant forms, the most common and classic presentation of **Alport's syndrome is X-linked recessive**, affecting males more severely. - This statement is incorrect because it implies that autosomal dominant inheritance is the primary or typical mode, which is not true for the majority of cases. *Nerve deafness* - **Sensorineural hearing loss**, particularly for high frequencies, is a common and characteristic extra-renal manifestation of Alport's syndrome. - This symptom typically progresses with age and is a key diagnostic feature. *Glomerulonephritis* - **Progressive glomerulonephritis** is the hallmark renal feature of Alport's syndrome, leading to hematuria, proteinuria, and eventually end-stage renal disease. - It is caused by mutations in collagen type IV genes, which disrupt the integrity of the glomerular basement membrane. *X-linked* - The majority of Alport's syndrome cases (about 85%) are **X-linked recessive**, caused by mutations in the *COL4A5* gene located on the X chromosome. - This explains why males are more severely affected and typically present with earlier onset and more rapid progression of renal disease.

Question 807: Which of the following statements about HIV associated nephropathy (HIVAN) is incorrect?

A. HIVAN is characterized by proteinuria.
B. HIVAN is associated with shrunken kidneys. (Correct Answer)
C. HIVAN typically develops when CD4 count is less than 200.
D. About 15% of cases show mesangial proliferation.

Explanation: ***Shrunken kidneys*** - In HIV-associated nephropathy, kidneys typically appear **enlarged** due to hyperplasia of podocytes and other glomerular changes. - **Shrunken kidneys** are not a characteristic feature, making this statement incorrect. *Develops when CD4<200* - HIV-associated nephropathy often arises when CD4 counts drop **below 200 cells/mm³**, indicating severe immunosuppression. - This is a common threshold for the occurrence of opportunistic infections and kidney issues in HIV patients. *15% cases show mesengial proliferation* - **Mesangial proliferation** can occur in about **15% to 30%** of cases of HIV-associated nephropathy, which aligns with the typical histological findings. - Incorrect assumptions might stem from misunderstanding the varying morphologies associated with HIV nephropathy. *Proteinuria* - **Proteinuria** is a common clinical feature of HIV-associated nephropathy, with the condition often presenting with significant protein loss in the urine. - The nephropathy especially results in **nephrotic syndrome**, characterized by high levels of proteinuria.

Question 808: What is the initial treatment of choice for managing secondary hyperparathyroidism in patients with renal osteodystrophy?

A. Cinacalcet
B. Bisphosphonates
C. Calcium restriction
D. Phosphate binders (Correct Answer)

Explanation: ***Phosphate binders*** - **Phosphate binders** are the initial treatment because **hyperphosphatemia** is the primary driver of secondary hyperparathyroidism in renal disease, triggering parathyroid hormone (PTH) release [1]. - They work by binding dietary phosphate in the gastrointestinal tract, preventing its absorption and thus lowering serum phosphate levels [1]. *Cinacalcet* - **Cinacalcet** is a calcimimetic that increases the sensitivity of calcium-sensing receptors on the parathyroid gland, reducing **PTH secretion** [1]. - It is often used if **phosphate binders** and **vitamin D analogs** are insufficient in controlling PTH, making it a second-line treatment [1]. *Bisphosphonates* - **Bisphosphonates** are used to treat osteoporosis by inhibiting osteoclast activity and reducing bone resorption. - They are generally contraindicated in advanced renal osteodystrophy due to concerns about adynamic bone disease and are not an initial treatment for **secondary hyperparathyroidism**. *Calcium restriction* - While restricting dietary calcium might seem intuitive, **hypocalcemia** is often a problem in renal disease due to impaired vitamin D activation [1]. - Overly restricting calcium can worsen hypocalcemia, which would further stimulate PTH release, thus it is not an initial treatment for **secondary hyperparathyroidism**.

Question 809: Which of the following electrolyte imbalances is least likely to be observed in Chronic Renal Failure (CRF)?

A. Hyperkalemia
B. Hyperphosphatemia
C. Hypercalcemia (Correct Answer)
D. Hypocalcemia

Explanation: ***Hypercalcemia*** - In **chronic renal failure (CRF)**, the kidneys' inability to activate vitamin D leads to impaired calcium absorption and **hypocalcemia** [1], [2]. - Additionally, the kidneys fail to excrete phosphate, leading to **hyperphosphatemia**, which further exacerbates hypocalcemia by forming calcium-phosphate precipitates [1]. *Hyperkalemia* - **Hyperkalemia** is a common and serious complication of CRF due to the kidneys' impaired ability to excrete **potassium**. - This is exacerbated by conditions like **metabolic acidosis** and certain medications. *Hyperphosphatemia* - In CRF, the kidneys are unable to adequately excrete **phosphate**, leading to an accumulation of **phosphate** in the blood [1]. - This condition directly contributes to **secondary hyperparathyroidism** and bone disease [1], [2]. *Hypocalcemia* - **Hypocalcemia** is very common in CRF, primarily due to decreased production of **calcitriol (active vitamin D)** by the failing kidneys [2]. - Reduced calcitriol leads to lower intestinal **calcium absorption** and impaired bone mineralization [1].

Question 810: Which of the following is a renal-specific nephropathy associated with HIV?

A. Focal Segmental Glomerulosclerosis (FSGS) (Correct Answer)
B. Mesangioproliferative Glomerulonephritis
C. Membranous Nephropathy
D. Membranoproliferative Glomerulonephritis (MPGN)

Explanation: ### Focal Segmental Glomerulosclerosis - It is a common renal complication associated with **HIV infection**, characterized by **podocyte injury** and segmental sclerosis [1]. - Often results in **nephrotic syndrome**, presenting with significant **proteinuria** and edema, making it distinct in HIV renal pathology [1]. ### Membranous Glomerulonephritis - Typically presents with **subepithelial immune complex deposits**, leading to a different pathophysiological mechanism. - More commonly associated with other secondary causes, such as **drugs** or **infection**, rather than being specific to HIV. ### Mesangioproliferative Glomerulonephritis - Characterized by **mesangial cell proliferation and immune complex deposition**, often linked with various infections but not specifically with HIV. - Usually shows **hematuria** and mild proteinuria, lacking the severe nephrotic syndrome seen in focal segmental glomerulosclerosis. ### Membranoproliferative Glomerulonephritis - Features **proliferation of mesangial and endothelial cells**, leading to a distinctive pattern on renal biopsy, not specific to HIV. - Typically presents in other contexts such as **chronic infections** or **autoimmune diseases**, rather than predominantly with HIV.

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Glomerular Diseases

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Tubulointerstitial Diseases

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Nephrotic and Nephritic Syndromes

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Urinary Tract Infections

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Renal Replacement Therapy

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Fluid and Electrolyte Disorders

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Acid-Base Disorders

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Kidney in Systemic Diseases

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Kidney Stones and Obstructive Uropathy

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Hypertension in Kidney Disease

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Nephrology — MCQs

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