Nephrology Practice Questions

Q: A patient with type 2 diabetes develops severe lactic acidosis on metformin. Which condition most likely precipitated this?

Acute kidney injury. ***Acute kidney injury*** - **Metformin** is primarily excreted by the kidneys; impaired renal function leads to drug accumulation and increased risk of **lactic acidosis** [1]. - **Acute kidney injury** reduces the clearance of metformin, which inhibits mitochondrial respiration and can exacerbate lactate production if it accumulates in the body [1]. *Peripheral neuropathy* - **Peripheral neuropathy** is a complication of diabetes, but it does not directly impact the metabolism or excretion of metformin. - It does not increase the risk of **metformin-associated lactic acidosis (MALA)**. *Urinary tract infection* - A **urinary tract infection (UTI)** can cause systemic inflammation and potentially mild dehydration, but it generally does not directly affect renal metformin clearance to the extent of causing severe lactic acidosis. - While a severe UTI could potentially contribute to **acute kidney injury** in some cases, it is not the direct precipitating factor for metformin accumulation. *Diabetic retinopathy* - **Diabetic retinopathy** is a microvascular complication of diabetes affecting the eyes. - It has no direct physiological link to metformin metabolism or excretion, and therefore does not contribute to the risk of **lactic acidosis** [2].

Q: Most sensitive early marker for diabetic nephropathy?

Microalbuminuria. ***Microalbuminuria*** - **Microalbuminuria** refers to the presence of abnormally high levels of **albumin** in the urine, typically between 30 and 300 mg/day [1]. - It's considered the **earliest detectable sign** of **diabetic nephropathy**, reflecting initial glomerular damage before overt proteinuria or changes in kidney function occur [2]. *Increased serum creatinine* - An increase in **serum creatinine** usually indicates a more significant decline in **glomerular filtration rate (GFR)**, suggesting later stages of kidney damage [2]. - It is not an early marker as it rises only after substantial kidney function has been lost. *Proteinuria >500mg/day* - **Overt proteinuria** (macroalbuminuria), often defined as albumin excretion exceeding 300 mg/day (or 500 mg/day in some classifications), represents a more advanced stage of kidney disease [2]. - This level of protein excretion occurs after microalbuminuria has been established and signifies further progression of renal damage. *Decreased GFR* - A **decreased GFR** (glomerular filtration rate) indicates reduced kidney function and is a later manifestation of **diabetic nephropathy** [2]. - Early stages of nephropathy often involve normal or even increased GFR before a significant decline is observed.

Q: A patient of CKD has presented with protracted vomiting. ABG shows pH = 7.40, pCO2 = 40 mm Hg, HCO3 = 24 mEq/L, Na = 145 mEq/L, Chloride = 100 mEq/L. What is the observation?

High anion gap metabolic acidosis and metabolic alkalosis. ***High anion gap metabolic acidosis and metabolic alkalosis*** - The **calculated anion gap** is 145 - (100 + 24) = 21, which is elevated (normal 8-12), indicating a **high anion gap metabolic acidosis**. [1] - The **ΔΔ ratio (ΔAG / ΔHCO3)** is (21-12) / (24-24) = 9/0, which is indeterminate but given the **normal pH and Bicarbonate**, a co-existing metabolic alkalosis that is compensating for the acidosis is likely. [1] *Normal anion gap metabolic acidosis* - This would be characterized by a **normal anion gap** (8-12 mEq/L), which is not the case here (elevated to 21 mEq/L). [1] - Normal anion gap acidosis usually involves **loss of bicarbonate** or **addition of chloride**, leading to hyperchloremia. *No acid base abnormality* - While the **pH and HCO3** are within the normal range, the elevated anion gap indicates an underlying acid-base disturbance. [1] - A comprehensive assessment, including anion gap calculation, reveals an abnormality **despite normal pH**. [1] *High anion gap metabolic acidosis* - Although there is a **high anion gap metabolic acidosis**, the **normal pH and bicarbonate** suggest a second primary acid-base disorder. [1] - In an isolated high anion gap metabolic acidosis, the pH and bicarbonate would typically be **lower than normal**.

Q: History of fever and sore throat. Patient is on antibiotics. Blood shows eosinophilia and urine shows WBC cast. Diagnosis?

Interstitial nephritis. ***Interstitial nephritis*** - The combination of **fever**, **eosinophilia**, and **WBC casts** [1] in the context of **antibiotic use** strongly suggests **acute interstitial nephritis (AIN)** [3]. - AIN is often an **allergic reaction to drugs** (like antibiotics, NSAIDs) leading to inflammation of the renal interstitium [1], [3]. *Lupus nephritis* - While Lupus nephritis affects the kidneys and can cause inflammation, it is typically associated with **immune complex deposition** and often presents with features of systemic lupus erythematosus [3], which are not described here. - **Eosinophilia** and **WBC casts** are not characteristic diagnostic features of lupus nephritis; **red blood cell casts** and **proteinuria** are more common. *Chronic Glomerulonephritis* - This condition involves long-term damage to the glomeruli, often leading to **proteinuria**, **hematuria**, and **hypertension**. - It does not typically present with **fever** or marked **eosinophilia**, and while red cell casts can occur, WBC casts are less indicative. *Chronic Pyelonephritis* - This is a long-standing **bacterial infection of the kidney** and renal pelvis, often leading to scarring. - While WBC casts can be present due to infection, **fever is usually acute**, and **eosinophilia is not a typical finding** unless it's related to a complication or a different underlying process [2].

Q: Which of the following is NOT a feature of nephrotic syndrome?

Hematuria. ### Original Explanation ***Hematuria*** - **Hematuria** is a characteristic feature of **nephritic syndrome**, which involves glomerular inflammation and damage leading to blood in the urine [1]. - In contrast, **nephrotic syndrome** is primarily characterized by increased glomerular permeability to protein, not red blood cells, resulting in significant **proteinuria** [1]. *Edema* - **Edema** is a hallmark of nephrotic syndrome, resulting from severe **hypoalbuminemia** that reduces plasma oncotic pressure [2]. - This leads to fluid extravasation into the interstitial spaces, causing generalized swelling. *Hypoalbuminemia* - **Hypoalbuminemia** is a defining feature of nephrotic syndrome, caused by excessive urinary loss of albumin due to widespread glomerular damage [2]. - Reduced serum albumin levels contribute to the characteristic edema and increased lipid synthesis by the liver. *Proteinuria* - **Proteinuria**, specifically *massive proteinuria* (>3.5 g/day in adults), is the cardinal feature of nephrotic syndrome [1], [2]. - It signifies significant damage to the glomerular filtration barrier, allowing large amounts of protein to leak into the urine.

Q: All of the following are indications for hemodialysis in acute kidney injury, EXCEPT:

Hypertension. ***Hypertension*** - While hypertension can be a complication of **acute kidney injury (AKI)**, it is generally managed with **antihypertensive medications** and **fluid removal**, and does not by itself necessitate urgent hemodialysis unless it is severe and refractory, alongside other uremic symptoms. - Hemodialysis primarily addresses life-threatening electrolyte imbalances, fluid overload, and uremic symptoms. [2] *Severe metabolic acidosis* - **Severe metabolic acidosis (pH 6.5 mEq/L)**, especially when refractory to medical management (e.g., insulin, glucose, calcium gluconate), is a major indication for hemodialysis. [1] - Hemodialysis is highly effective at rapidly lowering potassium levels, which is crucial to prevent cardiac arrhythmias. [1] *Pulmonary edema* - **Severe fluid overload** leading to **pulmonary edema** that is refractory to diuretic therapy is a strong indication for hemodialysis in AKI. [2] - Hemodialysis can efficiently remove excess fluid, thereby alleviating respiratory distress and improving oxygenation.

Q: A 58-year-old man with a history of smoking presents with hematuria. What is the most likely diagnosis?

Bladder cancer. ***Bladder cancer*** - **Smoking** is the strongest risk factor for bladder cancer, and **painless hematuria** is its most common presenting symptom [1]. - The combination of a long-term smoker and gross hematuria makes this the most concerning diagnosis [1]. *Renal cyst* - **Renal cysts** are typically asymptomatic and rarely cause gross hematuria unless they are large, complicated, or rupture. - While common, they are less likely to be the cause of hematuria in a smoker without other symptoms. *Pyelonephritis* - **Pyelonephritis** is an upper urinary tract infection characterized by fever, flank pain, dysuria, and often microscopic hematuria, but gross hematuria is less common. - This patient presents with hematuria without signs of infection. *Prostate cancer* - **Prostate cancer** usually presents with urinary obstructive symptoms (e.g., hesitancy, weak stream, nocturia) or is found incidentally on screening. - While microscopic hematuria can occur, gross hematuria as the sole presenting symptom is rare.

Q: Which of the following is TRUE about Nephrotic Syndrome?

Causes hyperlipidemia. ***Causes hyperlipidemia*** - **Nephrotic syndrome** leads to increased hepatic synthesis of lipoproteins in response to **hypoalbuminemia**, resulting in **hyperlipidemia** [3]. - This is a compensatory mechanism where the liver, trying to produce more albumin, also increases the production of other proteins, including lipoproteins. *Causes decreased risk of thrombosis* - **Nephrotic syndrome** actually causes an **increased risk of thrombosis** due to the urinary loss of anticoagulant proteins like **antithrombin III**, and increased levels of procoagulant factors [3]. - The combination of **hypercoagulability** and potential for vascular stasis significantly elevates thrombotic risk, especially deep vein thrombosis and renal vein thrombosis. *Is primarily characterized by decreased GFR* - While **glomerular filtration rate (GFR)** can be affected in some cases, the primary characteristic of **nephrotic syndrome** is massive **proteinuria** (typically >3.5 g/day), leading to **hypoalbuminemia**, **edema**, and **hyperlipidemia** [2], [3]. - A significant decrease in GFR is more characteristic of **nephritic syndrome** or advanced kidney disease, although some nephrotic conditions can progress to impact GFR [2]. *Commonly presents with hematuria* - **Hematuria** is a hallmark feature of **nephritic syndrome**, which involves glomerular inflammation and damage to the filtering barrier, allowing red blood cells to pass into the urine [1], [2]. - **Nephrotic syndrome**, in contrast, primarily involves a derangement of the glomerular basement membrane that selectively allows protein to pass, making **hematuria** an atypical or minor finding unless there is an overlap with nephritic features [2].

Q: A young adult presents with hematuria following a sore throat. Diagnosis?

IgA nephropathy. ***IgA nephropathy*** - **IgA nephropathy** often presents with **recurrent hematuria** that occurs concurrently with or shortly after an **upper respiratory tract infection** (like a sore throat) [1]. - This condition is characterized by the deposition of **IgA immune complexes** in the glomeruli, leading to microscopic or macroscopic hematuria [1], [3]. *Henoch-Schönlein purpura (HSP)* - While HSP is also an **IgA vasculitis** that can cause hematuria, it typically presents with a classic tetrad of symptoms: **palpable purpura**, **arthralgia**, **abdominal pain**, and **renal involvement**. - The patient in this case only presents with hematuria following a sore throat, lacking the other characteristic features of HSP. *Post-streptococcal glomerulonephritis (PSGN)* - **PSGN** typically presents with hematuria, edema, and hypertension about **1-3 weeks after** a streptococcal infection (e.g., strep throat) [2]. - The key differentiator is the **latency period** between the infection and the onset of renal symptoms, which is usually shorter or absent in IgA nephropathy [1]. *Goodpasture syndrome (GPS)* - **Goodpasture syndrome** is an autoimmune disease characterized by antibodies against the **glomerular basement membrane (GBM)**, leading to rapidly progressive glomerulonephritis and often pulmonary hemorrhage [3]. - It does not typically present with hematuria immediately following a sore throat and is not directly linked to such antecedent infections in the same manner as IgA nephropathy or PSGN.

Question 1

A patient with type 2 diabetes develops severe lactic acidosis on metformin. Which condition most likely precipitated this?

Accepted Answer

Acute kidney injury

Answer

Peripheral neuropathy

Answer

Urinary tract infection

Answer

Diabetic retinopathy

Question 2

Most sensitive early marker for diabetic nephropathy?

Accepted Answer

Microalbuminuria

Answer

Increased serum creatinine

Answer

Proteinuria >500mg/day

Answer

Decreased GFR

Question 3

A patient of CKD has presented with protracted vomiting. ABG shows pH = 7.40, pCO2 = 40 mm Hg, HCO3 = 24 mEq/L, Na = 145 mEq/L, Chloride = 100 mEq/L. What is the observation?

Accepted Answer

High anion gap metabolic acidosis and metabolic alkalosis

Answer

Normal anion gap metabolic acidosis

Answer

No acid base abnormality

Answer

High anion gap metabolic acidosis

Question 4

History of fever and sore throat. Patient is on antibiotics. Blood shows eosinophilia and urine shows WBC cast. Diagnosis?

Accepted Answer

Interstitial nephritis

Answer

Lupus nephritis

Answer

Chronic Glomerulonephritis

Answer

Chronic Pyelonephritis

Question 5

Which of the following is NOT a feature of nephrotic syndrome?

Accepted Answer

Hematuria

Answer

Edema

Answer

Hypoalbuminemia

Answer

Proteinuria

Question 6

Assertion: In a patient with chronic kidney disease (CKD) and metabolic acidosis, sodium bicarbonate should be initiated to correct acidosis.
Reason: Sodium bicarbonate therapy reduces the progression of kidney disease by decreasing tubular injury and slowing fibrosis.

Accepted Answer

Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion

Answer

Assertion is false, but Reason is true

Answer

Both Assertion and Reason are true, and Reason is the correct explanation of Assertion

Answer

Assertion is true, but Reason is false

Question 7

All of the following are indications for hemodialysis in acute kidney injury, EXCEPT:

Accepted Answer

Hypertension

Answer

Severe metabolic acidosis

Answer

Hyperkalemia

Answer

Pulmonary edema

Question 8

A 58-year-old man with a history of smoking presents with hematuria. What is the most likely diagnosis?

Accepted Answer

Bladder cancer

Answer

Renal cyst

Answer

Pyelonephritis

Answer

Prostate cancer

Question 9

Which of the following is TRUE about Nephrotic Syndrome?

Accepted Answer

Causes hyperlipidemia

Answer

Causes decreased risk of thrombosis

Answer

Is primarily characterized by decreased GFR

Answer

Commonly presents with hematuria

Question 10

A young adult presents with hematuria following a sore throat. Diagnosis?

Accepted Answer

IgA nephropathy

Answer

Henoch-Schönlein purpura (HSP)

Answer

Post-streptococcal glomerulonephritis (PSGN)

Answer

Goodpasture syndrome (GPS)

Nephrology — MCQs

Nephrology — MCQs

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