Nephrology Practice Questions

Q: Which of the following statements is FALSE regarding Autosomal dominant polycystic kidney disease (ADPKD)?

The polyductin gene is involved in ADPKD.. Autosomal Dominant Polycystic Kidney Disease (ADPKD) is primarily caused by mutations in the **PKD1** (Chromosome 16) or **PKD2** (Chromosome 4) genes [1], which encode the proteins polycystin-1 and polycystin-2, respectively. The **Polyductin** gene (also known as PKHD1) is associated with **Autosomal Recessive Polycystic Kidney Disease (ARPKD)**, not the dominant form. **Analysis of Incorrect Options (True statements):** * **Option A:** Berry (saccular) aneurysms are indeed the most common CNS manifestation of ADPKD. They occur due to defects in the arterial wall integrity associated with polycystin mutations. * **Option B:** Due to the prevalence of these aneurysms, patients with ADPKD have a significantly higher risk of subarachnoid hemorrhage (SAH) compared to the general population, especially if there is a positive family history of stroke or aneurysm. * **Option D:** Screening studies using MRA have shown that saccular aneurysms are present in approximately 5–10% of asymptomatic ADPKD patients. **High-Yield Clinical Pearls for NEET-PG:** * **Extra-renal manifestations:** Hepatic cysts (most common extra-renal site), Mitral Valve Prolapse (MVP), diverticulosis, and pancreatic cysts. * **Genetics:** PKD1 mutations (85% of cases) lead to earlier onset and faster progression to ESRD compared to PKD2 [1]. * **Diagnosis:** Ultrasonography is the primary screening tool; diagnostic criteria are based on the number of cysts relative to the patient's age. * **Management:** Tolvaptan (V2 receptor antagonist) is used to slow the increase in kidney volume and decline in GFR.

Q: Which of the following is the most accurate method to assess decline in GFR during initial stages of renal insufficiency?

Creatinine clearance. The Glomerular Filtration Rate (GFR) is the gold standard for assessing renal function. In the **initial stages** of renal insufficiency (early chronic kidney disease), **Creatinine Clearance (CrCl)** is the most accurate clinical method to detect a decline [2]. **Why Creatinine Clearance is correct:** Serum creatinine has a non-linear, hyperbolic relationship with GFR. In early stages of renal disease, a significant drop in GFR (up to 50%) can occur while the serum creatinine remains within the "normal" range (the "creatinine-blind" area) [1]. Creatinine clearance, which involves a 24-hour urine collection, accounts for both serum levels and urinary excretion, making it more sensitive than serum creatinine alone for detecting early functional loss [2]. **Why other options are incorrect:** * **Serum Creatinine:** It is an insensitive marker for early disease because it does not rise significantly until the GFR has fallen by approximately 50% [1]. It is affected by muscle mass, age, and gender. * **Serum BUN & Urea:** These are poor markers of GFR because they are heavily influenced by non-renal factors such as high-protein diet, dehydration, GI bleeding, and corticosteroid use [2]. Furthermore, urea undergoes significant tubular reabsorption. **High-Yield Pearls for NEET-PG:** * **Gold Standard:** Inulin Clearance is the absolute gold standard for measuring GFR but is rarely used clinically due to its exogenous nature and cost [2], [4]. * **Creatinine Secretion:** CrCl slightly **overestimates** GFR because a small amount of creatinine is secreted by the proximal tubules [5]. * **Best Formula:** The **CKD-EPI** formula is currently preferred over MDRD [3] for estimating GFR (eGFR) in clinical practice. * **Cystatin C:** An endogenous marker that is not affected by muscle mass and may be more sensitive than creatinine in early CKD.

Q: A patient undergoing hemodialysis becomes restless and complains of headache and nausea. Which complication do you suspect?

Disequilibrium syndrome. The patient is presenting with classic symptoms of **Dialysis Disequilibrium Syndrome (DDS)**. **1. Why the correct answer is right:** DDS is a neurological complication that typically occurs during or immediately after the first few sessions of hemodialysis. It is caused by the **rapid removal of urea** from the blood. Urea is an osmotically active solute; while it is cleared quickly from the plasma, it crosses the blood-brain barrier slowly. This creates an osmotic gradient that draws water into the brain cells, leading to **cerebral edema**. Clinical manifestations range from restlessness, headache, and nausea to more severe symptoms like seizures and coma. **2. Why the incorrect options are wrong:** * **Infection:** While common in dialysis patients (e.g., peritonitis or catheter-related sepsis), it usually presents with fever, chills, and localized pain rather than acute neurological symptoms during the procedure [1]. * **Air Embolism:** This is a sudden emergency characterized by acute dyspnea, chest pain, and hypotension (the "mill-wheel" murmur). It does not typically present with isolated restlessness and headache. * **Acute Hemolysis:** This presents with back pain, chest tightness, and a drop in hematocrit. The blood in the lines may appear "cherry red." **3. NEET-PG High-Yield Pearls:** * **Risk Factor:** Most common during the **first dialysis session** or when pre-dialysis BUN levels are extremely high (>150 mg/dL). * **Prevention:** Use a slower blood flow rate, shorter dialysis duration for the first session, or use osmotic agents like **Mannitol** to prevent rapid shifts. * **Management:** If DDS occurs, the dialysis should be slowed or stopped, and hypertonic solutions may be administered to reduce cerebral edema.

Q: Proximal and distal renal tubular acidosis are differentiated by all except?

Hypokalemia. To differentiate between Proximal (Type 2) and Distal (Type 1) Renal Tubular Acidosis (RTA), one must identify the unique clinical and biochemical markers of each [1]. **Why Hypokalemia is the correct answer:** Hypokalemia is **not** a differentiating factor because it is a common feature of **both** Type 1 (Distal) and Type 2 (Proximal) RTA. In Type 1, it occurs due to the inability to secrete H+, leading to compensatory K+ secretion [1]. In Type 2, the failure to reabsorb bicarbonate leads to increased distal delivery of sodium bicarbonate, which promotes potassium excretion. Since both conditions present with low serum potassium, it cannot be used to distinguish between them. **Explanation of other options (Differentiating factors):** * **Stones in kidney (Nephrolithiasis/Nephrocalcinosis):** This is a hallmark of **Type 1 RTA** (due to alkaline urine and hypercalciuria). It is typically **absent in Type 2 RTA** because the distal acidification remains intact, keeping calcium soluble. * **Daily acid secretion:** In **Type 1 RTA**, the primary defect is the inability to secrete H+ ions, leading to a high urinary pH (>5.5) [1]. In **Type 2 RTA**, the distal tubule can still secrete acid once the plasma bicarbonate levels drop below the threshold, allowing for a low urinary pH (<5.5). * **Presence of Fanconi syndrome:** This is specifically associated with **Type 2 RTA**. It involves a generalized dysfunction of the proximal tubule, leading to glycosuria, phosphaturia, and aminoaciduria alongside bicarbonate loss. **High-Yield NEET-PG Pearls:** * **Type 1 (Distal):** Inability to secrete H+; associated with Sjögren’s syndrome and Amphotericin B. * **Type 2 (Proximal):** Inability to reabsorb HCO3-; associated with Multiple Myeloma and Wilson’s disease. * **Type 4 (Hyperkalemic):** Associated with Diabetes Mellitus and hypoaldosteronism; the **only** RTA with **high** potassium.

Q: Recurrent gross hematuria is seen in which of the following conditions?

IgA nephropathy. Explanation: **IgA Nephropathy (Berger’s Disease)** is the most common cause of primary glomerulonephritis worldwide and is the classic cause of **recurrent gross hematuria**. The underlying pathophysiology involves the deposition of IgA-dominant immune complexes in the glomerular mesangium [2][3]. Characteristically, episodes of gross hematuria are triggered by an upper respiratory tract infection (synpharyngitic hematuria), occurring within 24–48 hours of the onset of infection [2]. **Analysis of Incorrect Options:** * **Alport’s Syndrome:** While it presents with persistent microscopic hematuria and can have episodes of gross hematuria, it is primarily characterized by a family history of renal failure, sensorineural hearing loss, and ocular abnormalities (lenticonus). It is a basement membrane disorder (Type IV Collagen mutation), not typically defined by "recurrent gross" episodes as its hallmark. * **Focal Segmental Glomerulosclerosis (FSGS):** This typically presents with nephrotic syndrome (heavy proteinuria, edema) [1][4]. While microscopic hematuria can occur, recurrent gross hematuria is not a feature. * **Diabetes Mellitus:** Diabetic nephropathy presents with progressive albuminuria and a decline in GFR [4]. Hematuria is rare; if present, it usually warrants investigation for other causes like papillary necrosis or malignancy [5]. **High-Yield Clinical Pearls for NEET-PG:** * **Synpharyngitic Hematuria:** Hematuria occurs *with* the infection (IgA Nephropathy) [2]. * **Post-Streptococcal GN (PSGN):** Hematuria occurs 1–3 weeks *after* the infection (latent period) [1][2]. * **Diagnosis:** Gold standard is Renal Biopsy showing **mesangial IgA deposits** and mesangial hypercellularity [3]. * **Prognosis:** The most reliable predictor of poor prognosis is the degree of proteinuria and hypertension at presentation.

Q: All of the following are true about Prerenal Azotemia, EXCEPT:

Plasma BUN/Creatinine ratio 20:1**. When renal perfusion decreases, the renin-angiotensin-aldosterone system (RAAS) is activated. This increases the reabsorption of sodium and water in the proximal tubule. Since urea follows sodium and water passively, urea reabsorption is significantly increased. Creatinine, however, is not reabsorbed. This leads to a disproportionate rise in blood urea nitrogen (BUN) relative to serum creatinine. A ratio ** 40):** True. In prerenal states, the kidneys are highly efficient at reabsorbing water. This concentrates the urine, leading to a high concentration of non-reabsorbable solutes like creatinine in the urine compared to the plasma. * **Option B (FENa < 1%):** True. This is the most sensitive index to differentiate prerenal azotemia from ATN. Intact tubules respond to hypoperfusion by maximally conserving sodium. * **Option C (Urinary output 500 mOsm/kg** (concentrated urine), whereas in ATN it is <350 mOsm/kg (isosthenuria). * **Urine Sodium:** Usually **<20 mEq/L** in prerenal states. * **Management:** Prerenal azotemia is reversible with prompt fluid resuscitation; failure to treat can lead to Intrinsic AKI (ATN) [1].

Q: A 70-year-old male, a known case of a certain malignancy, presents with elevated erythropoietin levels and a packed cell volume (PCV) of 52%. Which tumor is most likely responsible?

Renal Cell Carcinoma. ### **Explanation** **1. Why Renal Cell Carcinoma (RCC) is Correct:** The clinical presentation of elevated erythropoietin (EPO) and a high packed cell volume (PCV) in the presence of a malignancy points toward a **Paraneoplastic Syndrome**. RCC is the most common cause of **paraneoplastic erythrocytosis** [1], [3]. The tumor cells ectopically produce erythropoietin, which stimulates the bone marrow to increase red blood cell production, leading to secondary polycythemia (erythrocytosis) [3]. **2. Why the Other Options are Incorrect:** * **Medullary Thyroid Carcinoma:** Typically associated with the secretion of Calcitonin, CEA, or ACTH (leading to Cushing syndrome), but not EPO [2]. * **Gastric Carcinoma:** Often presents with iron deficiency anemia due to chronic occult blood loss, rather than erythrocytosis. * **Colorectal Carcinoma:** Similar to gastric cancer, it is a common cause of microcytic hypochromic anemia due to chronic GI bleeding. **3. High-Yield Clinical Pearls for NEET-PG:** * **Differential Diagnosis for Ectopic EPO Production:** Remember the mnemonic **"Potentially Really High Hematocrit"**: * **P**heochromocytoma * **R**enal Cell Carcinoma (Most common) [1] * **H**epatocellular Carcinoma (HCC) * **H**emangioblastoma (Cerebellar) * **U**terine Leiomyoma (Fibroids) * **Stauffer Syndrome:** A unique paraneoplastic syndrome in RCC characterized by reversible hepatic dysfunction (elevated ALP) without liver metastases. * **Classic Triad of RCC:** Hematuria, flank pain, and a palpable abdominal mass (seen in only 10% of cases). * **Investigation of Choice:** Contrast-Enhanced CT (CECT) of the abdomen [1].

Question 1

Which of the following statements is FALSE regarding Autosomal dominant polycystic kidney disease (ADPKD)?

Accepted Answer

The polyductin gene is involved in ADPKD.

Answer

Berry aneurysm is the most common central nervous system manifestation.

Answer

There is an increased risk of subarachnoid hemorrhage from a ruptured intracranial aneurysm.

Answer

Saccular aneurysms may be detected in up to 10% of asymptomatic patients.

Question 2

Which of the following is the most accurate method to assess decline in GFR during initial stages of renal insufficiency?

Accepted Answer

Creatinine clearance

Answer

Serum creatinine

Answer

Serum BUN

Answer

Serum urea

Question 3

A patient undergoing hemodialysis becomes restless and complains of headache and nausea. Which complication do you suspect?

Accepted Answer

Disequilibrium syndrome

Answer

Infection

Answer

Air embolism

Answer

Acute hemolysis

Question 4

A 50-year-old man with a history of diabetes presents with a poor urinary stream, increased frequency of micturition, and hesitancy. What is the most likely diagnosis?

Accepted Answer

Benign prostatic hyperplasia (BPH)

Answer

Urinary tract infection (UTI)

Answer

Atonic bladder

Answer

Autonomic neuropathy

Question 5

Proximal and distal renal tubular acidosis are differentiated by all except?

Accepted Answer

Hypokalemia

Answer

Stones in kidney

Answer

Daily acid secretion

Answer

Presence of Fanconi syndrome

Question 6

Recurrent gross hematuria is seen in which of the following conditions?

Accepted Answer

IgA nephropathy

Answer

Alport's syndrome

Answer

Focal segmental glomerulosclerosis

Answer

Diabetes mellitus

Question 7

A 27-year-old alcoholic man presents with decreased appetite, mild generalized weakness, intermittent mild abdominal pain, perioral numbness, and some cramping of his hands and feet. His physical examination is initially normal. His laboratory results show a sodium level of 140 mEq/L, potassium 4.0 mEq/L, calcium 6.9 mg/dL, albumin 3.5 g/dL, magnesium 0.7 mg/dL, and phosphorus 2.0 mg/dL. You go back to the patient and find that he has both a positive Trousseau and a positive Chvostek sign. Which of the following is the most likely cause of the hypocalcemia?

Accepted Answer

Decreased end-organ response to parathyroid hormone because of hypomagnesemia

Answer

Poor dietary intake

Answer

Hypoalbuminemia

Answer

Pancreatitis

Question 8

All of the following are true about Prerenal Azotemia, EXCEPT:

Accepted Answer

Plasma BUN/Creatinine ratio <20

Answer

Urinary Cr/Plasma Cr >40

Answer

FENa < 1

Answer

Urinary output < 400 ml/day

Question 9

A 70-year-old male, a known case of a certain malignancy, presents with elevated erythropoietin levels and a packed cell volume (PCV) of 52%. Which tumor is most likely responsible?

Accepted Answer

Renal Cell Carcinoma

Answer

Medullary thyroid carcinoma

Answer

Gastric Carcinoma

Answer

Colorectal Carcinoma

Question 10

Isosthenuria is seen in which of the following conditions?

Accepted Answer

Chronic renal failure

Answer

Diabetes insipidus

Answer

Congestive cardiac failure

Answer

Weil's disease

Nephrology — MCQs

Nephrology — MCQs

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