Nephrology Practice Questions

Q: Following surgery, a patient develops oliguria. You believe the patient is hypovolemic, but you seek corroborative data before increasing intravenous fluids. The best data is?

Fractional excretion of sodium less than 1. ***Fractional excretion of sodium less than 1*** - A **fractional excretion of sodium (FENa) less than 1%** is a classic indicator of **prerenal azotemia** or hypovolemia, as the kidneys are avidly reabsorbing sodium and water to preserve circulating volume. - This indicates the kidneys are functioning appropriately in response to perceived hypoperfusion, attempting to conserve sodium and thus water. *Urine chloride of 15 meq/L* - While a **low urine chloride** can sometimes be seen in volume depletion, it is not as specific or reliable an indicator of hypovolemia as FENa. - Urine chloride is more helpful in differentiating causes of **metabolic alkalosis**, particularly saline-responsive versus saline-unresponsive. *Urine sodium of 28 meq/L* - A urine sodium concentration of **less than 20 mEq/L** is a more classic cutoff for prerenal azotemia/hypovolemia, indicating aggressive sodium reabsorption. - A value of 28 mEq/L, although relatively low, is less definitive than a low FENa in strongly supporting hypovolemia. *Urine/Serum creatinine ratio of 20* - A **urine/serum creatinine ratio greater than 20:1** is indicative of prerenal azotemia, suggesting the kidneys are concentrating urine in response to hypovolemia. - While supportive, FENa is often considered a more precise and widely accepted marker, especially in the absence of diuretic use or chronic kidney disease.

Q: Renal transplantation is preferred in

Chronic glomerulonephritis. ***Chronic glomerulonephritis*** - **Chronic glomerulonephritis** is a common cause of end-stage renal disease (ESRD), requiring renal replacement therapy like transplantation. [1] - Transplantation offers the best long-term outcomes and quality of life compared to dialysis for suitable ESRD patients. [1] *AKI* - **Acute kidney injury (AKI)** is often reversible and does not typically require renal transplantation. [1] - Management focuses on treating the underlying cause to restore kidney function. [1] *Bilateral staghorn calculus* - **Bilateral staghorn calculi** are usually managed with surgical intervention to remove the stones and preserve renal function. - Renal transplantation is not indicated unless the stones lead to irreversible **end-stage renal disease**. [1] *Bilateral hydronephrosis* - **Bilateral hydronephrosis** is treated by relieving the obstruction causing urine backup. - Kidney transplantation is considered only if the obstruction leads to **irreversible kidney damage** and **ESRD**. [1]

Q: Edema in nephrotic syndrome is due to ?

Hypoalbuminemia. ***Hypoalbuminemia*** - In **nephrotic syndrome**, damage to the glomerular basement membrane leads to significant **proteinuria**, particularly the loss of **albumin**. [3] - **Hypoalbuminemia** reduces the plasma **oncotic pressure**, causing fluid to shift from the intravascular space into the interstitial space, resulting in **edema**. [1], [3] *Hyperlipidemia* - **Hyperlipidemia** is a common feature of nephrotic syndrome but is not directly responsible for the development of edema. - It results from increased hepatic synthesis of lipoproteins in response to low systemic **oncotic pressure**. *Sodium & water retention* - While **sodium and water retention** do contribute to the exacerbation of edema in nephrotic syndrome, they are secondary events driven by the initial **hypovolemia** resulting from **hypoalbuminemia**. [2] - The reduced effective circulating volume triggers the **renin-angiotensin-aldosterone system** and antidiuretic hormone release, leading to renal sodium and water reabsorption. *Increased venous pressure* - **Increased venous pressure** is not a primary cause of edema in nephrotic syndrome. - It is typically associated with conditions like **congestive heart failure** or local venous obstruction, where it impedes venous return and causes fluid accumulation.

Q: Basic abnormality in a case of nephrotic syndrome is:

Proteinuria. Basic abnormality in a case of nephrotic syndrome is: ***Proteinuria*** - The fundamental abnormality in nephrotic syndrome is **massive proteinuria** (protein excretion > 3.5 g/day in adults), resulting from increased glomerular permeability [1]. - This **proteinuria** leads to hypoalbuminemia, which then triggers many of the other clinical manifestations of the syndrome. *Hyperlipidemia* - **Hyperlipidemia** is a common consequence of nephrotic syndrome, driven by increased hepatic lipoprotein synthesis in response to low plasma oncotic pressure and reduced lipoprotein catabolism. - While characteristic, it is a **secondary abnormality** arising from the primary protein loss rather than the basic underlying cause. *Pedal edema* - **Pedal edema** is a prominent clinical feature of nephrotic syndrome, resulting from the combination of reduced plasma oncotic pressure due to hypoalbuminemia and secondary sodium and water retention [1]. - Although highly visible, it is a **symptom** and a downstream effect, not the primary pathological process. [1] *Hypertension* - **Hypertension** can occur in some cases of nephrotic syndrome, particularly with more severe renal involvement or concurrent fluid overload. - However, it is **not a universal feature** and is generally considered a complication or an associated condition, rather than the core initiating abnormality.

Q: A 17-year-old boy comes to the physician because of edema of both legs as well as pen- orbital edema There is no history of diarrhea and no urinary symptoms suggestive of infection. He had a throat infection 3 weeks ago. His blood pressure is 110/70 mmHg. He undergoes a kidney biopsy and light microscopy is normal. The patient is treated and makes a full recovery. Which of the following is the most likely diagnosis?

Minimal change glomerulonephritis. ***Minimal change glomerulonephritis*** - The presentation of **edema**, particularly **periorbital edema**, in a young patient without significant hypertension or hematuria, despite a recent infection, is highly suggestive of **nephrotic syndrome** [1]. - **Normal light microscopy** on kidney biopsy is characteristic of minimal change disease, as the pathology is primarily confined to **effacement of podocyte foot processes** visible only on electron microscopy [1]. *ANCA associated vasculitis* - ANCA-associated vasculitides typically present with **rapidly progressive glomerulonephritis** and systemic symptoms, often including **hematuria** and significant renal dysfunction, which are not described here. - While a kidney biopsy would show features of **pauci-immune crescentic glomerulonephritis**, light microscopy would not be normal [3]. *Post-streptococcal glomerulonephritis* - Often presents with **edema** and a history of a recent throat infection, but is primarily a **nephritic syndrome** characterized by **hematuria**, **hypertension**, and **red blood cell casts** in the urine [2]. - Light microscopy would show **diffuse proliferative glomerulonephritis** with immunoglobulin and complement deposits [2]. *Accelerated hypertension* - Accelerated hypertension is defined by a **sudden, severe increase in blood pressure** often associated with end-organ damage, such as papilledema, renal failure, or cardiac complications. - The patient's blood pressure of **110/70 mmHg is normal**, making accelerated hypertension an incorrect diagnosis.

Q: High anion gap acidosis is seen in all except:

Diarrhea. ***Diarrhea*** - Diarrhea causes **non-anion gap metabolic acidosis** due to the loss of bicarbonate from the gastrointestinal tract [3]. - The anion gap remains normal because chloride reabsorption in the kidneys increases to compensate for the lost bicarbonate. *Salicylate poisoning* - Salicylate poisoning causes **high anion gap metabolic acidosis** by uncoupling oxidative phosphorylation, leading to increased production of lactic acid and other organic acids [2]. - Early stages may also involve a superimposed respiratory alkalosis due to direct stimulation of the respiratory center [1]. *Acute renal failure* - Acute renal failure leads to a **high anion gap metabolic acidosis** because the kidneys are unable to excrete metabolic acids (e.g., phosphates, sulfates) and reabsorb bicarbonate effectively [3]. - This results in the accumulation of unmeasured anions and a decrease in serum bicarbonate. *Lactic acidosis* - Lactic acidosis is a common cause of **high anion gap metabolic acidosis**, resulting from increased production or decreased metabolism of lactic acid [1]. - It occurs when there is inadequate tissue oxygenation (Type A, e.g., shock) or other conditions like certain drugs or toxins (Type B) [1].

Q: A child has serum osmolality of 270 mOsm/kg and urine osmolality of 1200 mOsm/kg. What is the most probable diagnosis?

SIADH. SIADH - In SIADH (Syndrome of Inappropriate Antidiuretic Hormone), there is excessive ADH secretion, leading to water retention, low serum osmolality (dilute blood), and concentrated urine. [1] - The serum osmolality of 270 mOsm/kg is low-normal/mildly low [3], while the urine osmolality of 1200 mOsm/kg is very high [1], indicating the kidneys are inappropriately conserving water and concentrating urine despite diluted plasma. Nephrogenic diabetes insipidus - This condition involves the kidneys being unable to respond to ADH [2], leading to the excretion of large volumes of dilute urine despite dehydration. - While serum osmolality might be high due to dehydration, urine osmolality would be low (dilute), contrary to the given values. Water deprivation - In water deprivation, the body compensates by releasing ADH, which leads to concentrated urine to conserve water and a high serum osmolality. - Here, the serum osmolality is low-normal, which does not align with the expected high serum osmolality seen in water deprivation. Central diabetes insipidus - Characterized by the lack of ADH production by the pituitary gland [2], resulting in the excretion of large volumes of dilute urine. - Patients with central DI would typically have high serum osmolality (due to water loss) and low urine osmolality (dilute urine), which is the opposite of the given values.

Q: Pseudohyponatremia occurs in which of the following conditions?

Hyperlipidemia. Hyperlipidemia - Pseudohyponatremia, or **factitious hyponatremia**, occurs when the measured sodium concentration is artificially low due to an increased proportion of the non-aqueous component of plasma. - In severe hyperlipidemia, the elevated **lipid concentration** displaces plasma water, leading to a falsely low sodium reading when measured by flame photometry, as the electrode measures sodium concentration per unit of plasma, rather than per unit of plasma water. *CHF* - **Congestive Heart Failure** (CHF) causes true hyponatremia, often due to increased antidiuretic hormone (ADH) secretion in response to reduced effective circulating volume [1]. - This leads to **water retention** and dilutional hyponatremia, where the total body sodium is relatively preserved but is diluted by excess water [1]. *SIADH* - **Syndrome of Inappropriate Antidiuretic Hormone** (SIADH) causes true **euvolemic hyponatremia** due to excessive ADH release, leading to impaired free water excretion despite normal renal and adrenal function [1]. - This results in a dilutional hyponatremia, characterized by concentrated urine (**high urine osmolality**) and elevated urine sodium output. *Severe dehydration* - **Severe dehydration** typically leads to **hypernatremia** or isotonic hyponatremia, but rarely pseudohyponatremia. - True hyponatremia in dehydration is unusual unless there is predominant free water loss relative to solute loss, or inappropriate fluid replacement with hypotonic fluids.

Q: A CKD patient had to undergo dialysis. His Hb was 5.5. So two blood transfusions were to be given. First bag was completed in 2 hours. Second was started and midway between he developed shortness of breath, hypertension. Vitals: BP 180/120 mm Hg and pulse rate 110/min. What is the cause?

Transfusion related circulatory overload (TACO). ***Transfusion related circulatory overload (TACO)*** - The patient's presentation with **shortness of breath**, **hypertension**, and **tachycardia** following blood transfusion, especially in a **CKD patient** with likely compromised cardiac and renal function, is highly suggestive of **TACO** [1]. - **Fluid overload** from the transfused blood, exacerbated by pre-existing renal impairment, leads to acute pulmonary edema and cardiovascular stress. *Allergic* - Allergic reactions typically manifest with **urticaria**, **pruritus**, **bronchospasm**, or **anaphylaxis**, often without severe hypertension or primary respiratory distress in this manner [1], [2]. - While mild allergic reactions can occur, the prominent hypertension and acute respiratory distress point away from a simple allergic response. *FNHTR* - **Febrile non-hemolytic transfusion reaction (FNHTR)** is characterized by a temperature increase of at least 1°C, chills, and rigors, usually without significant respiratory distress or marked hypertension [1]. - The patient's symptoms are dominated by respiratory and cardiovascular overload rather than fever. *TRALI* - **Transfusion-related acute lung injury (TRALI)** is characterized by acute respiratory distress with **hypoxemia** and **bilateral pulmonary infiltrates** due to non-cardiogenic pulmonary edema, typically associated with hypotension, not hypertension. - The prominent hypertension and the patient's underlying CKD make TACO a more likely diagnosis than TRALI.

Question 1

Following surgery, a patient develops oliguria. You believe the patient is hypovolemic, but you seek corroborative data before increasing intravenous fluids. The best data is?

Accepted Answer

Fractional excretion of sodium less than 1

Answer

Urine chloride of 15 meq/L

Answer

Urine sodium of 28 meq/L

Answer

Urine/Serum creatinine ratio of 20

Question 2

Renal transplantation is preferred in

Accepted Answer

Chronic glomerulonephritis

Answer

AKI

Answer

Bilateral staghorn calculus

Answer

Bilateral hydronephrosis

Question 3

Edema in nephrotic syndrome is due to ?

Accepted Answer

Hypoalbuminemia

Answer

Hyperlipidemia

Answer

Sodium & water retention

Answer

Increased venous pressure

Question 4

Regarding FeNa, which of the following is true?

Accepted Answer

FeNa is higher in intrinsic renal failure than pre renal failure

Answer

Measurement of FeNa is NOT affected by use of diuretic

Answer

FeNa is lower in neonates when compared to children

Answer

FeNa is similar in both pre term and term neonate

Question 5

Basic abnormality in a case of nephrotic syndrome is:

Accepted Answer

Proteinuria

Answer

Hyperlipidemia

Answer

Pedal edema

Answer

Hypertension

Question 6

A 17-year-old boy comes to the physician because of edema of both legs as well as pen- 
orbital edema There is no history of diarrhea and no urinary symptoms suggestive of 
infection. He had a throat infection 3 weeks ago. His blood pressure is 110/70 mmHg. He 
undergoes a kidney biopsy and light microscopy is normal. The patient is treated and makes 
a full recovery.

Which of the following is the most likely diagnosis?

Accepted Answer

Minimal change glomerulonephritis

Answer

ANCA associated vasculitis

Answer

Post-streptococcal glomerulonephritis

Answer

Accelerated hypertension

Question 7

High anion gap acidosis is seen in all except:

Accepted Answer

Diarrhea

Answer

Salicylate poisoning

Answer

Acute renal failure

Answer

Lactic acidosis

Question 8

A child has serum osmolality of 270 mOsm/kg and urine osmolality of 1200 mOsm/kg. What is the most probable diagnosis?

Accepted Answer

SIADH

Answer

Nephrogenic diabetes insipidus

Answer

Water deprivation

Answer

Central diabetes insipidus

Question 9

Pseudohyponatremia occurs in which of the following conditions?

Accepted Answer

Hyperlipidemia

Answer

CHF

Answer

SIADH

Answer

Severe dehydration

Question 10

A CKD patient had to undergo dialysis. His Hb was 5.5. So two blood transfusions were to be given. First bag was completed in 2 hours. Second was started and midway between he developed shortness of breath, hypertension. Vitals: BP 180/120 mm Hg and pulse rate 110/min. What is the cause?

Accepted Answer

Transfusion related circulatory overload (TACO)

Answer

Allergic

Answer

FNHTR

Answer

TRALI

Nephrology — MCQs

Nephrology — MCQs

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