Nephrology Practice Questions

Q: RBC casts are seen in all the following conditions except:

Diabetic nephropathy. The presence of **RBC casts** in urine is a pathognomonic sign of **glomerular hematuria**, indicating an active inflammatory process within the glomerulus (Glomerulonephritis). [1] **1. Why Diabetic Nephropathy is the correct answer:** Diabetic nephropathy is a **non-inflammatory** glomerular disease characterized by basement membrane thickening and mesangial expansion (Kimmelstiel-Wilson nodules). [1] It typically presents with progressive proteinuria and a "bland" urinary sediment. While microscopic hematuria can occasionally occur, the formation of RBC casts is not a feature of this condition. **2. Analysis of Incorrect Options:** * **Wegener’s Granulomatosis (GPA):** This is a small-vessel vasculitis that causes **Pauci-immune Crescentic Glomerulonephritis**. [1] The intense glomerular inflammation leads to the leakage of RBCs into the nephron, forming casts. * **Systemic Lupus Erythematosus (SLE):** Lupus nephritis (especially Classes III and IV) involves immune complex deposition and severe glomerular inflammation, frequently resulting in RBC casts. [1] * **Infective Endocarditis:** This can cause **post-infectious glomerulonephritis** or embolic phenomena, leading to an active nephritic sediment containing RBC casts. [2] **Clinical Pearls for NEET-PG:** * **RBC Casts = Nephritic Syndrome:** Always look for these in cases of Post-Streptococcal GN (PSGN), Goodpasture syndrome, and Alport syndrome. [1], [2] * **Dysmorphic RBCs:** Like RBC casts, acanthocytes (mickey-mouse shaped RBCs) suggest a glomerular origin of bleeding. * **Bland Sediment:** Seen in Diabetic Nephropathy and Amyloidosis (mostly proteinuria). * **Fatty Casts/Maltese Cross:** Pathognomonic for **Nephrotic Syndrome**. * **Muddy Brown Casts:** Pathognomonic for **Acute Tubular Necrosis (ATN)**.

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: A 75-year-old man presents with a 24-hour history of acute onset left loin pain, which worsens intermittently and has not settled with simple analgesia. The patient has mild dementia and cannot recall his past medical history. Aspiration of synovial fluid from a previous episode showed negatively birefringent crystals. Which one of the following substances is likely to make up the majority of this man's calculus?

Uric acid. **Explanation:** The patient presents with classic **ureteric colic** (acute onset loin pain) and a significant history of **Gout**. The key diagnostic clue is the "negatively birefringent crystals" found in synovial fluid, which are pathognomonic for **Monosodium Urate** crystals. Patients with gout have hyperuricemia, which predisposes them to the formation of **Uric acid calculi**. * **Why Uric Acid is correct:** Approximately 20% of patients with gout develop uric acid stones. These stones form in acidic urine (pH < 5.5) where uric acid becomes insoluble. Unlike most renal stones, pure uric acid stones are **radiolucent** on X-ray but visible on CT (NCCT). * **Why other options are incorrect:** * **Calcium Oxalate:** While this is the most common type of renal stone overall, it is not specifically associated with gouty arthritis. * **Triple Phosphate (Struvite):** These are "infection stones" (Magnesium Ammonium Phosphate) associated with urease-producing bacteria like *Proteus*. They typically form staghorn calculi. * **Xanthine:** These are extremely rare and associated with hereditary xanthine oxidase deficiency or Allopurinol therapy (rarely). **Clinical Pearls for NEET-PG:** 1. **Crystal Morphology:** Uric acid crystals in urine are typically **rhomboid** or rosette-shaped. 2. **Radiology:** "Uric acid stones are **L**ucent on X-ray but **D**ense on CT" (L for Lucent). 3. **Management:** The mainstay of treatment for uric acid stones is **urinary alkalinization** (using Potassium Citrate) to a pH of 6.5–7.0, which can often dissolve the stones (Chemolysis). 4. **Birefringence:** Remember: **G**out = **N**egative (GN); **P**seudogout (Calcium Pyrophosphate) = **P**ositive (PP).

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

A patient with COPD experiencing pedal edema was prescribed thiazides. The patient reported excessive sleepiness, prompting an ABG analysis. The results are: pH 7.42, pCO2 67 mmHg, and HCO3 42 mEq/L. What is the diagnosis?

Accepted Answer

Metabolic alkalosis with respiratory acidosis

Answer

Metabolic alkalosis with compensatory respiratory alkalosis

Answer

Metabolic alkalosis with metabolic acidosis

Answer

High anion gap metabolic acidosis with paradoxical aciduria

Question 2

Which of the following is seen in nephrotic syndrome?

Accepted Answer

Low serum calcium

Answer

Raised AT-III

Answer

Low lipid

Answer

Platelet activation

Question 3

Uremic lung most often results due to –

Accepted Answer

Pulmonary edema

Answer

Fibrosis

Answer

Alveolar injury

Answer

Congestive cardiac liver

Question 4

RBC casts are seen in all the following conditions except:

Accepted Answer

Diabetic nephropathy

Answer

Wegener's granulomatosis

Answer

Systemic lupus erythematosus (SLE)

Answer

Infective endocarditis

Question 5

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 6

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 7

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 8

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 9

A 75-year-old man presents with a 24-hour history of acute onset left loin pain, which worsens intermittently and has not settled with simple analgesia. The patient has mild dementia and cannot recall his past medical history. Aspiration of synovial fluid from a previous episode showed negatively birefringent crystals. Which one of the following substances is likely to make up the majority of this man's calculus?

Accepted Answer

Uric acid

Answer

Xanthine

Answer

Triple phosphate

Answer

Calcium oxalate

Question 10

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

Nephrology — MCQs

Nephrology — MCQs

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