Nephrology Practice Questions

Q: In hemolytic uremic syndrome, which of the following is characteristic?

All of the above. **Hemolytic Uremic Syndrome (HUS)** is defined by a classic clinical triad: **Microangiopathic Hemolytic Anemia (MAHA), Thrombocytopenia, and Acute Kidney Injury (AKI).** It is most commonly seen in children following a prodrome of bloody diarrhea caused by Shiga toxin-producing *E. coli* (STEC), specifically serotype O157:H7. ### **Explanation of Options:** * **Microangiopathic Hemolytic Anemia (MAHA):** This is a hallmark of HUS. Endothelial injury leads to the formation of microthrombi in small vessels. As RBCs pass through these partially occluded vessels, they are mechanically shredded, resulting in **schistocytes** (fragmented cells) on a peripheral smear and a negative Coombs test. * **Thrombocytopenia and Renal Failure:** Platelets are consumed during the formation of microthrombi, leading to low platelet counts (usually <150,000/mm³). The renal microvasculature is particularly susceptible, leading to decreased GFR, oliguria, and hematuria. * **Normal Coagulative Profile:** This is a **critical diagnostic differentiator.** Unlike Disseminated Intravascular Coagulation (DIC), the coagulation cascade is not activated in HUS. Therefore, PT, aPTT, and Fibrinogen levels remain **normal**. ### **NEET-PG High-Yield Pearls:** * **Most common cause of AKI in children:** HUS. * **Pathogenesis:** Shiga toxin causes direct endothelial damage, primarily in the glomerulus. * **Atypical HUS:** Caused by uncontrolled activation of the alternative complement pathway (Factor H deficiency); treated with **Eculizumab**. * **Management:** Primarily supportive (fluids, dialysis). **Antibiotics and anti-motility agents are contraindicated** in STEC-HUS as they may increase toxin release and worsen the condition.

Q: An 8-year-old boy presents with a history of diarrhea followed by decreased urine output. Blood examination shows 90,000 thrombocytes/cm³. What is the most likely diagnosis?

Hemolytic Uremic Syndrome. ### Explanation The clinical presentation of an 8-year-old boy with a prodrome of **diarrhea**, followed by **decreased urine output** (acute kidney injury) and **thrombocytopenia** (90,000/cm³), is the classic triad of **Hemolytic Uremic Syndrome (HUS)**. #### Why Option A is Correct: HUS is the most common cause of acute renal failure in children. It typically follows an infection with Shiga toxin-producing *E. coli* (STEC), most commonly serotype **O157:H7**. The toxin causes endothelial damage, leading to microangiopathic hemolytic anemia (MAHA), thrombocytopenia (due to platelet consumption), and renal microthrombi resulting in oliguria. #### Why Other Options are Incorrect: * **B. Disseminated Intravascular Coagulation (DIC):** While DIC also presents with thrombocytopenia and renal failure, it is characterized by abnormal coagulation profiles (prolonged PT/aPTT and low fibrinogen). In HUS, the coagulation profile is typically **normal**. * **C. Hemophilia:** This is an X-linked recessive disorder causing factor VIII or IX deficiency. It presents with deep tissue bleeds or hemarthrosis, not diarrhea-associated renal failure or thrombocytopenia. * **D. Idiopathic Thrombocytopenic Purpura (ITP):** ITP presents with isolated thrombocytopenia, usually following a viral respiratory infection. It does not cause renal failure or follow a diarrheal prodrome. #### High-Yield Clinical Pearls for NEET-PG: * **The HUS Triad:** 1. Microangiopathic Hemolytic Anemia (Schistocytes on smear), 2. Thrombocytopenia, 3. Acute Kidney Injury. * **Management:** Primarily supportive (fluid/electrolyte balance, dialysis). **Antibiotics and anti-motility agents are contraindicated** as they may increase toxin release and worsen the condition. * **Atypical HUS:** Caused by uncontrolled complement activation (Factor H deficiency); it does not require a diarrheal prodrome.

Q: An infant with a history of diarrhea 5 days back presents with urea of 200 mg% and creatinine of 5 mg/dL. The platelet count is 90,000/mm 3. Fragmented RBCs are found in the peripheral smear. What is the most likely diagnosis?

Hemolytic Uremic Syndrome (HUS). ### Explanation The clinical presentation describes the classic **triad of Hemolytic Uremic Syndrome (HUS)**: 1. **Microangiopathic Hemolytic Anemia (MAHA):** Evidence of fragmented RBCs (schistocytes) on peripheral smear. 2. **Thrombocytopenia:** Platelet count <150,000/mm³ (90,000 in this case). 3. **Acute Kidney Injury (AKI):** Significantly elevated Urea (200 mg%) and Creatinine (5 mg/dL). The history of **diarrhea** 5 days prior strongly suggests **Typical HUS**, usually caused by Shiga toxin-producing *E. coli* (STEC, O157:H7). The toxin damages glomerular endothelial cells, leading to microthrombi formation, which consumes platelets and mechanically shears RBCs. #### Why the other options are incorrect: * **Thrombotic Thrombocytopenic Purpura (TTP):** While it shares the MAHA and thrombocytopenia features, TTP is rare in infants and typically presents with a **pentad** including prominent neurological symptoms and fever. It is caused by ADAMTS13 deficiency. * **Idiopathic Thrombocytopenic Purpura (ITP):** ITP presents with isolated thrombocytopenia. It does **not** cause fragmented RBCs (hemolysis) or renal failure. * **Hemolytic Anemia:** This is a broad term. While hemolysis is present here, it does not account for the concurrent thrombocytopenia and acute renal failure. #### NEET-PG High-Yield Pearls: * **Most common cause of AKI in children:** HUS. * **Typical HUS:** Preceded by bloody diarrhea (*E. coli* O157:H7); prognosis is generally good with supportive care. * **Atypical HUS:** Due to alternative complement pathway dysregulation; carries a poorer prognosis and requires Eculizumab. * **Management:** Primarily supportive (fluids, dialysis). **Antibiotics and anti-motility agents are contraindicated** in STEC-HUS as they may increase toxin release.

Q: What is the most devastating consequence of hypernatremic dehydration in children?

Brain hemorrhage. **Explanation:** In hypernatremic dehydration (Serum Na+ >150 mEq/L), the extracellular fluid (ECF) becomes hypertonic. To maintain osmotic equilibrium, water moves out of the intracellular space into the ECF. When this occurs in the central nervous system, the **brain cells shrink**. As the brain volume decreases, it pulls away from the meninges, putting mechanical tension on the fragile **bridging veins**. This tension leads to the rupture of these vessels, resulting in **subdural, subarachnoid, and intracerebral hemorrhages**. This is considered the most devastating consequence due to the high risk of permanent neurological deficit or death. **Analysis of Incorrect Options:** * **A. Seizures:** While common during hypernatremia (due to cellular dehydration) or during rapid rehydration (due to cerebral edema), they are usually manageable and less "devastating" than a major intracranial bleed. * **B. Hyperglycemia:** Often seen in hypernatremic dehydration due to stress-induced insulin resistance and decreased insulin secretion, but it is a metabolic association rather than a life-threatening structural consequence. * **D. Hypocalcemia:** Frequently associated with hypernatremia (mechanism unclear, possibly related to calcium entry into cells), but it is rarely the primary cause of mortality or long-term morbidity in these patients. **High-Yield Clinical Pearls for NEET-PG:** * **The "Doughy" Skin Feel:** A classic physical exam finding in hypernatremic dehydration due to the preservation of ECF volume at the expense of ICF. * **Management Rule:** Never lower Serum Na+ faster than **0.5 mEq/L/hour** (or 10–12 mEq/L per 24 hours) to prevent **Cerebral Edema**. * **Idiogenic Osmoles:** The brain produces these (e.g., taurine, sorbitol) to protect itself from shrinking during chronic hypernatremia; rapid rehydration makes these osmoles pull water into the brain too quickly.

Q: What is the most common cause of renovascular hypertension in children and young adults?

Fibromuscular dysplasia. **Explanation:** Renovascular hypertension (RVH) is the most common cause of secondary hypertension in the pediatric population. It occurs due to the narrowing of one or more renal arteries, leading to the activation of the Renin-Angiotensin-Aldosterone System (RAAS). **1. Why Fibromuscular Dysplasia (FMD) is correct:** In children and young adults, **Fibromuscular Dysplasia** is the leading cause of renovascular hypertension. It is a non-inflammatory, non-atherosclerotic angiopathy that causes abnormal growth within the arterial wall. In children, the **intimal** subtype is most common, whereas the **medial** subtype (classic "string of beads" appearance) is more frequent in adults. Another significant cause in the Indian context is Takayasu Arteritis, but FMD remains the global textbook answer for this demographic. **2. Why the other options are incorrect:** * **Atherosclerotic disease:** This is the most common cause of RVH in the **elderly**, typically occurring at the ostium of the renal artery. It is rare in children. * **Ectopic kidney:** While anatomical variations can sometimes be associated with abnormal vasculature, they are not a primary cause of renovascular hypertension. * **Polycystic kidney disease (PKD):** PKD causes hypertension through intrarenal ischemia and RAAS activation due to cyst expansion, but it is classified as a **parenchymal** cause of hypertension, not a renovascular one. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** Digital Subtraction Angiography (DSA). * **Initial Screening:** Doppler Ultrasonography or CT Angiography. * **Associated Syndromes:** Always screen for RVH in children with Neurofibromatosis type 1 (NF-1) or Williams syndrome. * **Bruit:** A continuous epigastric or flank bruit is a specific clinical sign of RVH.

Q: Which of the following is true about a child with post-streptococcal glomerulonephritis?

Severe renal dysfunction is an indication for biopsy. **Explanation:** **Post-Streptococcal Glomerulonephritis (PSGN)** is the most common cause of acute nephritic syndrome in children, typically occurring 1–3 weeks after a pharyngeal or skin infection with Group A Beta-hemolytic Streptococcus. **Why Option C is Correct:** PSGN is generally a self-limiting condition with a favorable prognosis. A renal biopsy is **not** routinely required for diagnosis. However, atypical features necessitate a biopsy to rule out other glomerular diseases (like RPGN or SLE). Indications for biopsy include: * **Severe renal dysfunction** (Rapidly rising creatinine or AKI). * Persistent low C3 levels beyond 8 weeks. * Significant proteinuria (nephrotic range) or persistent gross hematuria. * Absence of a latent period or evidence of streptococcal infection. **Analysis of Incorrect Options:** * **Option A:** While gross hematuria usually resolves within 1–2 weeks, **microscopic hematuria** can persist for a long duration, often up to **6 months to 1 year**. * **Option B:** Increased serum triglycerides are a hallmark of **Nephrotic Syndrome**, not Nephritic Syndrome (PSGN). PSGN is characterized by the nephritic triad: Hematuria, Hypertension, and Edema. * **Option D:** PSGN is a classic example of the **alternative complement pathway** activation. Therefore, **Serum C3 is characteristically low** in >90% of patients during the acute phase, typically returning to normal within 6–8 weeks. **High-Yield Clinical Pearls for NEET-PG:** * **Most common finding:** Microscopic hematuria. * **First sign of recovery:** Diuresis and resolution of edema/hypertension. * **Best screening test:** Antistreptolysin O (ASO) titer (higher in pharyngitis) or Anti-DNase B (more sensitive for skin infections/impetigo). * **Electron Microscopy:** Characterized by subepithelial "humps" (lumpy-bump appearance).

Question 1

In hemolytic uremic syndrome, which of the following is characteristic?

Accepted Answer

All of the above

Answer

Thrombocytopenia and renal failure

Answer

Normal coagulative profile

Answer

Microangiopathic hemolytic anemia

Question 2

A 9-year-old boy presents with decreased urine output, cola-colored urine, and swelling of the face and hands for 2 days. He is hypertensive, has a puffy face, and pitting edema of the lower limbs. Four weeks prior, he had skin lesions. A diagnosis of post-streptococcal glomerulonephritis is made. If an antibiotic is to be used to limit the spread of nephritogenic organisms, what is the drug of choice?

Accepted Answer

Penicillin

Answer

Cefixime

Answer

Meropenem

Answer

Amoxycillin

Question 3

Which one of the following statements is false with regard to pyuria in children?

Accepted Answer

Presence of more than 5 white blood cells/high power field for girls and more than 3 white blood cells/high power field for boys

Answer

Infection can occur without pyuria

Answer

Pyuria may be present without urinary tract infection

Answer

Isolated pyuria is neither confirmatory nor diagnostic for urinary tract infection

Question 4

What is the most common cause of urinary ascites?

Accepted Answer

Posterior urethral valve

Answer

Bilateral pelviureteric junction obstruction

Answer

Meatal stenosis

Answer

Infantile polycystic kidney disease

Question 5

An 8-year-old boy presents with a history of diarrhea followed by decreased urine output. Blood examination shows 90,000 thrombocytes/cm³. What is the most likely diagnosis?

Accepted Answer

Hemolytic Uremic Syndrome

Answer

Disseminated Intravascular Coagulation

Answer

Hemophilia

Answer

Idiopathic Thrombocytopenic Purpura

Question 6

An infant with a history of diarrhea 5 days back presents with urea of 200 mg% and creatinine of 5 mg/dL. The platelet count is 90,000/mm
3. Fragmented RBCs are found in the peripheral smear. What is the most likely diagnosis?

Accepted Answer

Hemolytic Uremic Syndrome (HUS)

Answer

Thrombotic Thrombocytopenic Purpura (TTP)

Answer

Idiopathic Thrombocytopenic Purpura (ITP)

Answer

Hemolytic Anemia

Question 7

What is the most devastating consequence of hypernatremic dehydration in children?

Accepted Answer

Brain hemorrhage

Answer

Seizures

Answer

Hyperglycemia

Answer

Hypocalcemia

Question 8

Recurrent hematuria in a deaf-mute patient is seen in which of the following conditions?

Accepted Answer

Alport syndrome

Answer

Fanconi anemia

Answer

Renal tubular acidosis

Answer

Nephrotic syndrome

Question 9

What is the most common cause of renovascular hypertension in children and young adults?

Accepted Answer

Fibromuscular dysplasia

Answer

Atherosclerotic disease

Answer

Ectopic kidney

Answer

Polycystic kidney disease

Question 10

Which of the following is true about a child with post-streptococcal glomerulonephritis?

Accepted Answer

Severe renal dysfunction is an indication for biopsy

Answer

Microscopic hematuria decreases within 4 weeks

Answer

Serum triglyceride levels increase

Answer

Serum C3 levels are normal

Nephrology — MCQs

Nephrology — MCQs

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