Nephrology Practice Questions

Q: Pre-Renal Azotemia is characterized by all of the following findings, EXCEPT:

Urinary sodium concentration > 40 meq/L. **Explanation:** Pre-renal azotemia is a state of renal hypoperfusion (e.g., dehydration, hemorrhage, or heart failure) where the kidney's structural integrity is intact, but the glomerular filtration rate (GFR) is reduced [1]. [2] **Why Option C is the correct answer (The Exception):** In pre-renal states, the kidneys respond to hypoperfusion by activating the Renin-Angiotensin-Aldosterone System (RAAS). Aldosterone acts on the distal tubules to maximize sodium reabsorption to expand intravascular volume [3]. Consequently, the **Urinary Sodium concentration is typically LOW ( 40 mEq/L is characteristic of **Acute Tubular Necrosis (ATN)**, where tubular damage prevents the kidney from reabsorbing sodium. **Analysis of Incorrect Options:** * **Option A (FeNa 500 mOsm/kg):** In response to hypovolemia, ADH (Vasopressin) is secreted, causing the kidneys to reabsorb water and produce highly concentrated urine [1]. * **Option D (Reversible with fluids):** By definition, pre-renal azotemia is a functional abnormality. Restoring renal perfusion with IV fluids or blood quickly corrects the GFR and normalizes creatinine [2]. **High-Yield Clinical Pearls for NEET-PG:** * **BUN/Creatinine Ratio:** In pre-renal azotemia, the ratio is typically **> 20:1** (due to increased passive reabsorption of urea). * **Urine Sediment:** Usually shows **normal or hyaline casts** in pre-renal states, whereas **muddy brown granular casts** are seen in ATN. * **Fractional Excretion of Urea (FeUrea):** Useful if the patient is on diuretics; a **FeUrea < 35%** suggests a pre-renal etiology.

Q: Which of the following conditions is NOT associated with an increased anion-gap type of metabolic acidosis?

COPD. **Explanation:** The core concept tested here is the classification of acid-base disorders [2]. Metabolic acidosis is categorized based on the **Anion Gap (AG)**, calculated as $[Na^+] - ([Cl^-] + [HCO_3^-])$. An increased AG indicates the presence of unmeasured anions (organic acids). **Why COPD is the correct answer:** Chronic Obstructive Pulmonary Disease (COPD) causes **Respiratory Acidosis**, not metabolic acidosis [2]. In COPD, alveolar hypoventilation leads to the retention of carbon dioxide ($CO_2$), resulting in hypercapnia. While the body may compensate by increasing bicarbonate ($HCO_3^-$) levels via the kidneys, the primary pathology is respiratory [1]. It does not involve the accumulation of fixed metabolic acids that would increase the anion gap. **Analysis of Incorrect Options (Causes of High AG Metabolic Acidosis):** * **Shock (Option A):** Leads to tissue hypoperfusion and anaerobic metabolism, resulting in the accumulation of **Lactic Acid** [1]. * **Ingestion of Antifreeze (Option B):** Ethylene glycol is metabolized into toxic acids like **glycolic and oxalic acid**, which significantly raise the anion gap. * **Diabetic Ketoacidosis (Option C):** Insulin deficiency leads to the production of ketoacids (**beta-hydroxybutyrate and acetoacetate**), which are unmeasured anions. **NEET-PG High-Yield Pearls:** * **Mnemonic for High AG Metabolic Acidosis:** **MUDPILES** (Methanol, Uremia, DKA, Propylene glycol, Iron/INH, Lactic acidosis, Ethylene glycol, Salicylates). * **Normal AG Metabolic Acidosis (NAGMA):** Primarily caused by GI loss of $HCO_3^-$ (Diarrhea) or renal loss (Renal Tubular Acidosis) [1]. * **Golden Rule:** In any case of metabolic acidosis, always calculate the Anion Gap first to narrow the differential diagnosis.

Q: Which of the following conditions can cause transient proteinuria?

All of the above. **Explanation:** **Transient proteinuria** (also known as functional proteinuria) is a benign, self-limiting condition characterized by a temporary increase in urinary protein excretion in the absence of underlying structural renal disease. It is the most common cause of proteinuria in children and young adults. **Why the correct answer is "All of the above":** The underlying mechanism involves hemodynamic changes in the kidney [3]. Stressors cause alterations in renal blood flow and increased glomerular capillary pressure, leading to a temporary "leakage" of proteins (primarily albumin) across the glomerular basement membrane. * **Fever (Option A):** High body temperature increases metabolic demand and alters glomerular permeability. * **Dehydration (Option B):** Reduced intravascular volume leads to renal vasoconstriction and sluggish blood flow, which can concentrate proteins in the filtrate. * **Heavy Exercise (Option C):** Intense physical activity triggers sympathetic nervous system activation and the renin-angiotensin system, causing transient renal vasoconstriction and increased glomerular pressure [2]. **Clinical Pearls for NEET-PG:** * **Diagnosis:** Transient proteinuria is diagnosed when a follow-up urinalysis (usually after 24–48 hours of rest or resolution of the stressor) is **negative** for protein. * **Quantification:** It typically results in less than 1 gram of protein per day. * **Orthostatic (Postural) Proteinuria:** Another benign variant where protein is present only when the patient is upright [3]. It is diagnosed using a **split-urine collection** (day vs. night). * **Management:** No specific treatment or renal biopsy is required for transient proteinuria; reassurance is the mainstay of management. * **Rule of Thumb:** Persistent proteinuria (detected on two or more occasions) always warrants further investigation for glomerular or tubular disease [1].

Q: A long-term diabetic patient is found to have microalbuminuria. What is the typical daily excretion range of albumin in mg/day?

30 - 300 mg/day. **Explanation:** Microalbuminuria is the earliest clinical sign of **Diabetic Nephropathy** and represents a level of albumin excretion that is higher than normal but below the detection limit of a standard urine dipstick [1]. 1. **Why Option B is Correct:** The standard clinical definition of microalbuminuria is a persistent albumin excretion rate of **30–300 mg/day** (measured via 24-hour urine collection). On a random spot urine sample, this corresponds to an **Albumin-to-Creatinine Ratio (ACR) of 30–300 mg/g**. This range indicates early glomerular damage where the basement membrane's charge selectivity is compromised [2], but the damage is still potentially reversible with strict glycemic and blood pressure control (specifically using ACE inhibitors or ARBs). 2. **Why Other Options are Incorrect:** * **Option A (100–150 mg/day):** This is a subset of the microalbuminuria range but does not define its lower or upper limits. * **Option C (201–300 mg/day):** This represents "high-range" microalbuminuria, often seen just before progressing to overt nephropathy. * **Option D (301–600 mg/day):** Excretion **>300 mg/day** is classified as **Macroalbuminuria** (Overt Nephropathy or Clinical Albuminuria). At this stage, the urine dipstick becomes positive for protein. **High-Yield Clinical Pearls for NEET-PG:** * **Screening:** Type 1 Diabetics should be screened 5 years after diagnosis; Type 2 Diabetics should be screened **at the time of diagnosis** [1]. * **Gold Standard:** 24-hour urine collection is the gold standard, but **Spot Morning ACR** is the preferred screening method due to convenience. * **Diagnosis:** Requires at least **2 out of 3** positive specimens over a 3-to-6-month period. * **Management:** ACE inhibitors or ARBs are the drugs of choice as they reduce intraglomerular pressure by dilating the efferent arteriole.

Question 1

What are the classic clinical signs suggestive of acute pyelonephritis?

Accepted Answer

Chills, fever, and flank pain

Answer

Focal scar in the renal cortex

Answer

Septicemia

Answer

Altered renal function

Question 2

Pre-Renal Azotemia is characterized by all of the following findings, EXCEPT:

Accepted Answer

Urinary sodium concentration > 40 meq/L

Answer

Fractional Excretion of Sodium (FeNa) < 1%

Answer

Urinary osmolality > 500 mosm/kg

Answer

Reversible with replacement fluids

Question 3

What is the mechanism of hypokalemia in Gitelman syndrome?

Accepted Answer

Mineralocorticoid excess

Answer

Apparent mineralocorticoid excess

Answer

Distal delivery of non-reabsorbed anions

Answer

Magnesium deficiency

Question 4

A 43-year-old woman develops acute renal failure following an emergency resection of a leaking abdominal aortic aneurysm. Three days after surgery, the following laboratory values are obtained: Serum electrolytes (mEq/L): Na+:127; K+:5.9; Cl-:92; HCO3-:15. Blood urea nitrogen: 82 mg/dL. Serum creatinine: 6.7 mg/dL. The patient has gained 4 kg since surgery and is mildly dyspneic at rest. Eight hours after these values are reported, an electrocardiogram shows peaked T waves. What is the initial treatment for this patient?

Accepted Answer

10% calcium gluconate, 10 mL

Answer

Digoxin, 0.25 mg every 3 h for three doses

Answer

Oral Kayexalate

Answer

Lidocaine, 100 mg

Question 5

Which drug can be used in patients of cardio-renal syndrome?

Accepted Answer

Insulin

Answer

NSAIDS

Answer

ACEI

Answer

ARB

Question 6

Which of the following conditions is NOT associated with an increased anion-gap type of metabolic acidosis?

Accepted Answer

COPD

Answer

Shock

Answer

Ingestion of antifreeze

Answer

Diabetic ketoacidosis

Question 7

Which of the following conditions can cause transient proteinuria?

Accepted Answer

All of the above

Answer

Fever

Answer

Dehydration

Answer

Heavy exercise

Question 8

A long-term diabetic patient is found to have microalbuminuria. What is the typical daily excretion range of albumin in mg/day?

Accepted Answer

30 - 300 mg/day

Answer

100 - 150 mg/day

Answer

201 - 300 mg/day

Answer

301 - 600 mg/day

Question 9

Which intervention should be planned for a patient with renal calculi?

Accepted Answer

Strain all urine

Answer

Maintain bed rest

Answer

Increase dietary purines

Answer

Restrict fluids

Question 10

The "half-and-half" nail or "half-nail" sign, seen in uremia, is primarily caused by which of the following?

Accepted Answer

Increased capillary density in the proximal half of the nail bed

Answer

Melanin deposition in the nail bed

Answer

Hypoproteinemia leading to edema

Answer

Accumulation of circulating toxins affecting nail matrix

Nephrology — MCQs

Nephrology — MCQs

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