Nephrology Practice Questions

Q: The Modification of Diet in Renal Disease (MDRD) formula for estimation of glomerular filtration rate (GFR) does not include which of the following?

Body weight. The Modification of Diet in Renal Disease (MDRD) formula for estimation of glomerular filtration rate (GFR) does not include which of the following? ***Body weight*** - The **MDRD formula** for GFR estimation does not include body weight as a variable [1]. - While body surface area is indirectly considered in some GFR estimations, the MDRD equation specifically omits actual body weight [1]. *Age* - **Age** is a key component of the MDRD formula, as GFR naturally declines with increasing age. - This adjustment helps account for age-related differences in creatinine production and renal function. *Sex* - **Sex** is included in the MDRD formula because men generally have a higher muscle mass and thus higher serum creatinine levels than women for the same GFR. - This adjustment factor helps to normalize GFR estimation between sexes. *Race* - **Race**, specifically African American ethnicity, is a factor in the MDRD formula due to observed differences in **creatinine generation** and GFR at similar serum creatinine levels. - This adjustment aims to improve the accuracy of GFR estimation across different racial groups.

Q: Which of the following is the LEAST common characteristic of nephrotic syndrome?

Lipiduria. ***Lipiduria*** - While lipiduria can occur in nephrotic syndrome, particularly with **severe proteinuria**, it is not a universally present clinical diagnostic criterion. - Its presence is a consequence of lipoprotein filtration rather than a direct defining feature of the syndrome itself. *Hypoalbuminemia* - This is a cardinal feature, defined as **serum albumin < 3.0 g/dL**, resulting from significant urinary protein loss. - It drives the generalized edema characteristic of nephrotic syndrome by reducing plasma oncotic pressure [1]. *Hyperlipidemia* - This is a very common characteristic due to increased hepatic synthesis of lipoproteins and decreased catabolism, often presenting as elevated **cholesterol and triglycerides**. - It is a risk factor for cardiovascular complications in nephrotic patients [1]. *Proteinuria > 3.5 gm per 1.73 m2 per 24 hours* - This is the **defining feature** of nephrotic syndrome, indicating significant damage to the glomerular filtration barrier [1]. - Massive proteinuria leads to the other key clinical manifestations of the syndrome.

Q: Causes of metabolic alkalosis include all the following except:

Mineralocorticoid deficiency. ***Mineralocorticoid deficiency*** - **Mineralocorticoid deficiency** (e.g., in Addison's disease) leads to decreased **aldosterone** secretion, resulting in **hyperkalemia** and **metabolic acidosis**, not alkalosis [1]. - Aldosterone normally promotes **potassium excretion** and **hydrogen ion excretion** in the renal tubules; its absence causes their retention [1]. *Bartter's syndrome* - **Bartter's syndrome** is a genetic disorder affecting the **thick ascending limb of the loop of Henle**, leading to impaired sodium, potassium, and chloride reabsorption. - This results in increased delivery of sodium to the collecting duct, stimulating **aldosterone secretion** and causing **hypokalemia** and **metabolic alkalosis** [1]. *Thiazide diuretic therapy* - **Thiazide diuretics** inhibit sodium and chloride reabsorption in the **distal convoluted tubule**, increasing sodium delivery to the collecting duct. - This promotes **potassium and hydrogen ion excretion**, leading to **hypokalemia** and **metabolic alkalosis** [1]. *Chronic respiratory acidosis* - In **chronic respiratory acidosis**, the kidneys compensate by increasing **bicarbonate reabsorption** and **hydrogen ion excretion**. - If the kidneys overcompensate or other factors are involved, this can sometimes lead to a **metabolic alkalosis** on top of the respiratory acidosis (e.g., in patients with COPD who also receive diuretics).

Q: An asymptomatic patient has proteinuria and hematuria that is glomerular in origin on a routine urinalysis. Which of the following is the most likely diagnosis?

immunoglobulin A (IgA) nephropathy (Berger's disease). ***immunoglobulin A (IgA) nephropathy (Berger's disease)*** - **IgA nephropathy** often presents with **asymptomatic gross or microscopic hematuria** and proteinuria, which can be glomerular in origin [1]. - It is one of the most common causes of **glomerular hematuria** and can be discovered incidentally on routine urinalysis [1]. *diabetes mellitus (DM) - nephropathy* - While **diabetic nephropathy** causes proteinuria, **hematuria is not a primary or prominent feature** in the early stages; it typically presents with progressive proteinuria and kidney function decline [2]. - Patients with **diabetic nephropathy** are usually symptomatic with **long-standing diabetes** and often associated complications. *amyloidosis - nephropathy* - **Nephropathy due to amyloidosis** primarily presents with **heavy proteinuria**, leading to **nephrotic syndrome**, but hematuria is uncommon. - Systemic amyloidosis often involves other organs, and patients typically present with other associated symptoms like **fatigue, weight loss, or organ dysfunction**. *focal glomerulosclerosis - nephropathy* - **Focal segmental glomerulosclerosis (FSGS)** typically presents with **nephrotic syndrome** (heavy proteinuria, edema, hypoalbuminemia), with microscopic hematuria being inconsistent and often mild. - While it can be primary (idiopathic), it more commonly presents with symptoms of **nephrotic range proteinuria** rather than isolated asymptomatic hematuria and proteinuria.

Q: Which of the following advice is not given to a 35-year-old female patient with recurrent renal stones?

Restrict calcium intake. ***Restrict calcium intake*** - For most types of renal stones (especially **calcium oxalate stones**), restricting dietary calcium is generally **not recommended** as it can ironically lead to increased oxalate absorption and higher stone formation risk. - Adequate calcium intake is important to bind dietary oxalate in the gut, reducing its absorption and subsequent excretion in the urine. *Increase water* - **Increased fluid intake** is a cornerstone in preventing all types of renal stones by promoting a higher urine volume, which dilutes stone-forming substances [1]. - This advice is crucial as it helps reduce the supersaturation of calcium, oxalate, and other mineral salts in the urine, making crystal formation less likely [1]. *Restrict protein* - **High animal protein intake** can increase the excretion of calcium, uric acid, and oxalate, while decreasing citrate excretion, all of which promote stone formation. - Limiting animal protein is a standard recommendation, particularly for patients with a history of **calcium oxalate** and **uric acid stones**. *Restrict salt* - High dietary sodium intake increases urinary calcium excretion and can promote the crystallization of calcium salts in the urine. - Therefore, **reducing salt intake** is a critical recommendation to lower urine calcium levels and prevent recurrent renal stones.

Q: Prerenal and renal azotemia are differentiated on the basis of.

Sodium fraction excretion. ***Sodium fraction excretion*** - **Fractional excretion of sodium (FENa)** is a key indicator for differentiating prerenal azotemia from intrinsic renal azotemia [2]. - In **prerenal azotemia**, the kidneys avidly reabsorb sodium to conserve volume, leading to a **low FENa ( 2%)** due to impaired sodium reabsorption [2]. *Creatinine clearance* - **Creatinine clearance** is a measure of **glomerular filtration rate (GFR)**, which is reduced in both prerenal and renal azotemia [1], [3]. - It does not specifically differentiate between the underlying cause of the reduced GFR (i.e., whether it's due to hypoperfusion or intrinsic kidney damage). *Serum creatinine level* - An **elevated serum creatinine level** is present in both prerenal and renal azotemia, indicating **renal dysfunction** [1]. - This measurement alone cannot distinguish whether the kidney injury is due to decreased perfusion or damage to the kidney itself. *Urine bicarbonate level* - **Urine bicarbonate levels** are primarily relevant in the assessment of **renal tubular acidosis** or other acid-base disorders. - They do not play a direct role in differentiating between prerenal and renal causes of azotemia.

Q: Glomerulonephritis in streptococcal infection is diagnosed by.

ASO Titre. ***ASO Titre*** - ASO (Antistreptolysin O) **titre** measures antibodies raised against streptococcal toxins, which are elevated following a **streptococcal infection**. - A high or rising ASO titre indicates a **recent streptococcal infection**, which is crucial for diagnosing **post-streptococcal glomerulonephritis**. *Blood culture* - **Blood culture** identifies the presence of bacteria in the bloodstream (bacteremia) but is typically negative in post-streptococcal glomerulonephritis as the infection itself often resolves before nephritis develops. - It would be more useful for diagnosing **active systemic infections**, such as endocarditis or sepsis, rather than a post-infectious immune-mediated complication. *Throat culture* - A **throat culture** detects the presence of *Streptococcus pyogenes* in the pharynx, confirming a current or very recent **streptococcal pharyngitis**. - While helpful for diagnosing the initial infection, it may be negative by the time glomerulonephritis manifests, as the bacteria might have been cleared. *PCR* - **PCR (Polymerase Chain Reaction)** detects bacterial DNA and can confirm the presence of *Streptococcus pyogenes* DNA directly in a sample. - While sensitive for detecting current infection, it does not directly diagnose the **immune-mediated complication** of glomerulonephritis, which is a delayed response.

Q: Mainstay of treatment of nephrogenic diabetes insipidus is:

Thiazide / Amiloride diuretics and salt restriction. ***Thiazide / Amiloride diuretics and salt restriction*** - **Thiazide diuretics** (e.g., hydrochlorothiazide) are the mainstay in nephrogenic diabetes insipidus by causing mild **volume depletion**, which enhances proximal tubular reabsorption of water and solutes, reducing urine volume. [1] - **Salt restriction** further supports this mechanism by helping to decrease filtered sodium load and consequently reducing water excretion. [1] *Desmopressin* - **Desmopressin** is a synthetic analog of **vasopressin** and is the primary treatment for **central diabetes insipidus**, where there is insufficient ADH production. [2] - In **nephrogenic diabetes insipidus**, the kidneys are resistant to ADH, so desmopressin would be ineffective. [2] *Vasopressin and salt restriction* - **Vasopressin** (arginine vasopressin, AVP) is the natural antidiuretic hormone whose action is impaired in nephrogenic diabetes insipidus due to **renal resistance**, making its administration ineffective. [2] - While salt restriction is beneficial, combining it with ineffective vasopressin would not be the mainstay of treatment. *Desmopressin with salt restriction* - As mentioned, **desmopressin** is ineffective in **nephrogenic diabetes insipidus** because the renal tubules are unresponsive to its action. [2] - Although **salt restriction** is a useful adjunct, its combination with an ineffective drug does not make it the mainstay of treatment for this specific condition.

Q: A boy is suffering from acute pyelonephritis. The most specific urinary finding will be:

W.B.C. casts. ***W.B.C. casts*** - **WBC casts** are pathognomonic for **pyelonephritis** as they indicate inflammation and infection within the **renal tubules**. - They form when white blood cells aggregate in the **tubular lumen** and are encased in **Tamm-Horsfall protein**, reflecting their renal origin. *Leucocyte esterase test* - The **leukocyte esterase test** detects the presence of enzymes released by **neutrophils**, indicating pyuria (white blood cells in urine). - While positive in pyelonephritis, it is not specific to the kidney and can be positive in **lower urinary tract infections** as well. *Nitrite test* - A **nitrite test** detects the presence of **nitrites**, which are formed by gram-negative bacteria that convert urinary nitrates. - This test is indicative of a bacterial infection but is not specific to the **upper urinary tract** (pyelonephritis) versus a **lower urinary tract infection** (cystitis). *Bacteria in gram stain* - The presence of **bacteria** on a Gram stain of unspun urine indicates a significant bacterial presence, often associated with a urinary tract infection. - However, it does not differentiate between **upper** (pyelonephritis) and **lower** (cystitis) urinary tract infections and is therefore not specific for pyelonephritis.

Question 1

The Modification of Diet in Renal Disease (MDRD) formula for estimation of glomerular filtration rate (GFR) does not include which of the following?

Accepted Answer

Body weight

Answer

Sex

Answer

Race

Answer

Age

Question 2

Which of the following is the LEAST common characteristic of nephrotic syndrome?

Accepted Answer

Lipiduria

Answer

Hyperlipidemia

Answer

Hypoalbuminemia

Answer

Proteinuria > 3.5 gm per 1.73 m2 per 24 hours

Question 3

Causes of metabolic alkalosis include all the following except:

Accepted Answer

Mineralocorticoid deficiency

Answer

Bartter's syndrome

Answer

Thiazide diuretic therapy

Answer

Chronic respiratory acidosis

Question 4

An asymptomatic patient has proteinuria and hematuria that is glomerular in origin on a routine urinalysis. Which of the following is the most likely diagnosis?

Accepted Answer

immunoglobulin A (IgA) nephropathy (Berger's disease)

Answer

diabetes mellitus (DM) - nephropathy

Answer

amyloidosis - nephropathy

Answer

focal glomerulosclerosis - nephropathy

Question 5

Which of the following advice is not given to a 35-year-old female patient with recurrent renal stones?

Accepted Answer

Restrict calcium intake

Answer

Increase water

Answer

Restrict salt

Answer

Restrict protein

Question 6

Prerenal and renal azotemia are differentiated on the basis of.

Accepted Answer

Sodium fraction excretion

Answer

Creatinine clearance

Answer

Serum creatinine level

Answer

Urine bicarbonate level

Question 7

Glomerulonephritis in streptococcal infection is diagnosed by.

Accepted Answer

ASO Titre

Answer

Blood culture

Answer

Throat culture

Answer

PCR

Question 8

Which of the following statements about autosomal dominant polycystic kidney disease (ADPKD) is incorrect?

Accepted Answer

Low Renin due to pressure atrophy of JG apparatus is a common finding in ADPKD.

Answer

Spider leg deformity

Answer

Anemia

Answer

Cysts increase in size with age

Question 9

Mainstay of treatment of nephrogenic diabetes insipidus is:

Accepted Answer

Thiazide / Amiloride diuretics and salt restriction

Answer

Vasopressin and salt restriction

Answer

Desmopressin

Answer

Desmopressin with salt restriction

Question 10

A boy is suffering from acute pyelonephritis. The most specific urinary finding will be:

Accepted Answer

W.B.C. casts

Answer

Bacteria in gram stain

Answer

Leucocyte esterase test

Answer

Nitrite test

Nephrology — MCQs

Nephrology — MCQs

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