Nephrology Practice Questions

Q: What is the bacterial count in a midstream urine specimen that defines a urinary tract infection?

10^5 or over. ### Explanation The diagnosis of a Urinary Tract Infection (UTI) is traditionally based on the concept of **significant bacteriuria**, a term introduced by Edward Kass. **Why 10⁵ or over is correct:** The threshold of **≥10⁵ colony-forming units (CFU) per mL** in a clean-catch midstream urine (MSU) sample was established to distinguish true infection from urethral or vaginal contamination. In asymptomatic individuals, this count has a high specificity (approx. 95%) for identifying actual bacterial multiplication in the bladder rather than transient flora introduced during voiding. **Why other options are incorrect:** * **A, B, and C (100, 1000, 10⁴):** While these counts can represent infection in specific clinical contexts (e.g., symptomatic women, catheterized patients, or suprapubic aspirates), they do not meet the standard diagnostic criteria for "significant bacteriuria" in a routine midstream specimen. Lower counts are often considered indicative of contamination in an asymptomatic patient. **High-Yield Clinical Pearls for NEET-PG:** * **Kass Criteria:** Originally defined as ≥10⁵ CFU/mL of a single uropathogen in two consecutive midstream urine samples in asymptomatic women. * **Symptomatic Patients:** In women with classic symptoms of cystitis (dysuria, frequency), a lower threshold of **≥10² to 10³ CFU/mL** is often considered clinically significant. * **Catheterized Patients:** A count of **≥10² CFU/mL** is sufficient to diagnose infection. * **Suprapubic Aspiration:** **Any** bacterial growth (even <10² CFU/mL) is considered significant because the bladder is normally sterile. * **Sterile Pyuria:** Presence of WBCs in urine with no growth on standard media; consider *Chlamydia*, *Ureaplasma*, or Renal Tuberculosis.

Q: A physician has been treating a 60-year-old patient with renal failure due to polycystic kidney disease. Which of the following conditions should the physician be specifically concerned about as a possible coexistence?

Berry aneurysm. **Explanation:** **Autosomal Dominant Polycystic Kidney Disease (ADPKD)** is a systemic multisystem disorder, not limited to the kidneys [1]. The correct answer is **Berry aneurysm** because ADPKD is the most common systemic condition associated with intracranial "berry" aneurysms, occurring in approximately 5–10% of these patients. **Why Berry Aneurysm is correct:** The genetic mutations in ADPKD (PKD1 and PKD2) affect **polycystin** proteins, which are expressed in the vascular smooth muscle and endothelium [1]. Defective polycystin leads to weakened arterial walls, predisposing patients to saccular (berry) aneurysms, particularly in the **Circle of Willis**. Rupture of these aneurysms leads to subarachnoid hemorrhage (SAH), a major cause of morbidity in ADPKD. **Why other options are incorrect:** * **A. Aneurysm of the aortic root:** While ADPKD is associated with thoracic aortic aneurysms and dissection, it is much less characteristic and frequent than berry aneurysms [2]. * **B. Atherosclerotic aneurysm:** These are typically found in the abdominal aorta and are related to smoking, hypertension, and age [2], rather than the specific genetic pathology of ADPKD. * **C. Cystic medial necrosis:** This is the classic pathology associated with **Marfan Syndrome** [2], leading to aortic dissection, not the primary vascular pathology of ADPKD. **High-Yield Clinical Pearls for NEET-PG:** * **Extra-renal manifestations of ADPKD:** Hepatic cysts (most common extra-renal site), Pancreatic cysts, **Mitral Valve Prolapse (MVP)**, and Diverticulosis. * **Screening:** Routine screening for berry aneurysms is not recommended for all ADPKD patients unless there is a positive family history of SAH or the patient is in a high-risk occupation (e.g., pilot). * **Genetics:** PKD1 (Chromosome 16) is more common and progresses to ESRD faster; PKD2 (Chromosome 4) is less severe [1].

Q: Polycystic kidney disease may be associated with cysts in all the following organs except:

Brain. Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a systemic multisystem disorder [1] characterized by the development of cysts in various epithelial-lined organs. **Why Brain is the correct answer:** While ADPKD is famously associated with **Berry aneurysms** (found in the Circle of Willis in approximately 5–10% of patients), it does **not** typically cause the formation of parenchymal cysts within the brain tissue itself. Therefore, while there are vascular abnormalities in the brain, "brain cysts" are not a feature of the disease. **Analysis of incorrect options:** * **Liver (Option B):** This is the most common extrarenal manifestation of ADPKD. Polycystic liver disease occurs in about 70–90% of patients over their lifetime. * **Pancreas (Option C):** Pancreatic cysts are the second most common extrarenal site, occurring in approximately 5–10% of patients. They are usually asymptomatic. * **Lung (Option A):** Though rare, pulmonary cysts and bronchiectasis have been documented in patients with ADPKD. **High-Yield Clinical Pearls for NEET-PG:** * **Genetics:** Most cases are due to mutations in **PKD1** (Chromosome 16 - more severe) or **PKD2** (Chromosome 4 - slower progression) [1]. * **Extrarenal Manifestations:** * **Cysts:** Liver (most common), Pancreas, Spleen, Seminal vesicles, Arachnoid membrane (not brain parenchyma). * **Non-cystic:** Berry aneurysms (can lead to Subarachnoid Hemorrhage), Mitral Valve Prolapse (MVP), Diverticulosis, and Inguinal hernias. * **Clinical Presentation:** Hypertension (earliest sign), hematuria, and palpable bilateral flank masses [1]. * **Diagnosis:** Ultrasonography is the initial screening modality of choice.

Q: What is the most common early sign of kidney disease?

Elevated BUN level. **Explanation:** The correct answer is **B. Elevated BUN level.** In the early stages of chronic kidney disease (CKD), the most sensitive indicator of a declining Glomerular Filtration Rate (GFR) is an increase in nitrogenous waste products in the blood [1]. As the number of functioning nephrons decreases, the kidney's ability to clear urea is compromised, leading to an **elevation in Blood Urea Nitrogen (BUN)**. While serum creatinine is also used, BUN often rises early as GFR begins to fall below 50% of normal [2]. **Analysis of Incorrect Options:** * **A. Sodium retention:** This typically occurs in later stages of renal failure. In early CKD, the remaining nephrons compensate by increasing fractional excretion of sodium to maintain balance. * **C. Development of metabolic acidosis:** This is a feature of advanced kidney disease (usually Stage 4 or 5). It occurs when the kidneys can no longer excrete the daily acid load or regenerate sufficient bicarbonate [1]. * **D. Inability to dilute or concentrate urine:** While **isosthenuria** (the inability to concentrate or dilute urine, resulting in a fixed specific gravity of ~1.010) is a classic sign of renal tubular damage, it generally manifests after a significant loss of nephron mass, following the initial rise in nitrogenous wastes. **NEET-PG High-Yield Pearls:** * **Isosthenuria:** A fixed urine specific gravity of **1.010** (equal to plasma osmolality) is a hallmark of chronic renal failure. * **Creatinine vs. BUN:** Creatinine is more specific for renal function, but it may stay within "normal" limits until nearly 50% of kidney function is lost (the "creatinine blind" area) [2]. * **First Clinical Sign:** While elevated BUN is a common early laboratory sign, the **earliest clinical sign** of diabetic nephropathy specifically is **microalbuminuria** (30-300 mg/day) [3].

Q: What is the initial treatment of acute hyperkalemia?

Calcium gluconate administration. **Explanation:** The management of acute hyperkalemia follows a specific hierarchy: membrane stabilization, intracellular shifting, and finally, elimination. **1. Why Calcium Gluconate is the Correct Choice:** In acute hyperkalemia (especially with ECG changes), the immediate priority is to protect the heart [1]. Hyperkalemia increases the resting membrane potential, bringing it closer to the threshold, which leads to myocardial excitability and potential arrhythmias [2]. **Calcium gluconate** (or calcium chloride) acts within **1–3 minutes** to stabilize the cardiac myocyte membrane by antagonizing the effect of potassium [1]. It does *not* lower serum potassium levels but prevents fatal arrhythmias. **2. Analysis of Incorrect Options:** * **Option B:** While insulin and glucose (Dextrose) effectively shift potassium into cells, the response begins within **20–30 minutes**, not 4 hours. It is the most reliable method for temporary shifting but is not the "initial" life-saving step if ECG changes are present. * **Option C:** Dialysis is the **most definitive** treatment for removing potassium from the body. It is highly useful in acute hyperkalemia, especially in patients with renal failure or those refractory to medical therapy. * **Option D:** Cation exchange resins (e.g., Sodium Polystyrene Sulfonate) take **several hours to days** to work and are not suitable for acute, emergency management. **High-Yield Clinical Pearls for NEET-PG:** * **ECG Sequence:** Tall peaked T-waves → PR prolongation → Loss of P-wave → Widened QRS (Sine wave) → VF/Asystole [2]. * **Calcium Dose:** 10 ml of 10% Calcium Gluconate over 10 minutes [1]. * **Salbutamol:** Beta-2 agonists also shift K+ intracellularly but should be used with caution in patients with tachycardia or CAD. * **Rule of Thumb:** If the question mentions ECG changes, **Calcium Gluconate** is always the first step [1].

Q: Which of the following is NOT a manifestation of polycystic kidney disease?

Urine retention. Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a systemic hereditary disorder characterized by the progressive growth of numerous cysts in the renal parenchyma [1]. **Why "Urine Retention" is the correct answer:** Urine retention is typically a feature of **lower urinary tract obstruction** (e.g., Benign Prostatic Hyperplasia, urethral strictures, or neurogenic bladder). While ADPKD causes significant kidney enlargement, it involves the renal parenchyma and does not inherently obstruct the outflow of urine from the bladder. Therefore, it is not a classic manifestation of the disease. **Analysis of incorrect options:** * **Renal Hypertension:** This is the most common early manifestation. It occurs due to cyst expansion, which causes local ischemia and triggers the **Renin-Angiotensin-Aldosterone System (RAAS)**. * **Renal Failure:** Progressive displacement of functional nephrons by expanding cysts leads to chronic kidney disease (CKD) [1]. ADPKD is a leading cause of end-stage renal disease (ESRD) requiring dialysis or transplant. * **Hematuria:** This occurs frequently due to the rupture of a cyst into the collecting system or associated nephrolithiasis (kidney stones) [1]. **NEET-PG High-Yield Pearls:** * **Extra-renal manifestations:** The most common is **Liver cysts** (Polycystic Liver Disease). The most life-threatening is **Berry Aneurysms** (Circle of Willis), which can lead to Subarachnoid Hemorrhage. * **Genetics:** Most cases are due to mutations in the **PKD1** gene (Chromosome 16), which presents earlier and more severely than **PKD2** (Chromosome 4) [1]. * **Diagnosis:** Ultrasonography is the initial screening tool of choice. * **Treatment:** Tolvaptan (Vasopressin V2 receptor antagonist) is used to slow cyst progression.

Question 1

What is the bacterial count in a midstream urine specimen that defines a urinary tract infection?

Accepted Answer

10^5 or over

Answer

100

Answer

1000

Answer

10^4

Question 2

A physician has been treating a 60-year-old patient with renal failure due to polycystic kidney disease. Which of the following conditions should the physician be specifically concerned about as a possible coexistence?

Accepted Answer

Berry aneurysm

Answer

Aneurysm of the aortic root

Answer

Atherosclerotic aneurysm

Answer

Cystic medial necrosis

Question 3

A 40-year old male complains of a vague dragging sensation in his abdomen for the last 6 months. There was no history of fever, renal colic or dysuria. Physical examination reveals a blood pressure at 150/96 mm Hg. Renal ultrasound shows bilaterally enlarged kidneys with multiple cysts. Urinalysis reveals mild proteinuria, 4 WBCs/HPF, and 10 RBCs/HPF. What is the most likely underlying renal pathology?

Accepted Answer

Polycystic kidney disease

Answer

Nephrolithiasis

Answer

Enlarged prostate

Answer

Deposition of immune complexes in the glomeruli

Question 4

Polycystic kidney disease may be associated with cysts in all the following organs except:

Accepted Answer

Brain

Answer

Lung

Answer

Liver

Answer

Pancreas

Question 5

What is the commonest cause of chronic renal failure?

Accepted Answer

Chronic pyelonephritis

Answer

Chronic glomerulonephritis

Answer

Multiple myeloma

Answer

Subacute bacterial endocarditis

Question 6

What dietary intervention is most appropriate for managing chyluria?

Accepted Answer

Medium chain fatty acids

Answer

Small chain fatty acids

Answer

Long chain fatty acids

Answer

Omega 3 unsaturated fatty acids

Question 7

Which of the following is NOT typically seen in chronic renal failure?

Accepted Answer

Hypercalcemia

Answer

Hyperkalemia

Answer

Hyponatremia

Answer

Hyperphosphatemia

Question 8

What is the most common early sign of kidney disease?

Accepted Answer

Elevated BUN level

Answer

Sodium retention

Answer

Development of metabolic acidosis

Answer

Inability to dilute or concentrate urine

Question 9

What is the initial treatment of acute hyperkalemia?

Accepted Answer

Calcium gluconate administration

Answer

Insulin and glucose administration reduces hyperkalemia within 4 hours

Answer

Dialysis is not useful in acute hyperkalemia

Answer

Resin administration shows a response within minutes

Question 10

Which of the following is NOT a manifestation of polycystic kidney disease?

Accepted Answer

Urine retention

Answer

Renal hypertension

Answer

Renal failure

Answer

Hematuria

Nephrology — MCQs

Nephrology — MCQs

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