Nephrology Practice Questions

Q: Pseudohyponatremia is found in all of the following EXCEPT:

Aldosterone excess. ***Aldosterone excess*** - **Aldosterone excess** typically leads to increased **sodium reabsorption** [2] and potassium excretion [1], which can result in **hypernatremia** or normal sodium levels, but not pseudohyponatremia. - It does not interfere with the measurement of plasma sodium concentration. *Extreme hyperproteinemia* - **Extreme hyperproteinemia** leads to an increase in the non-aqueous component of plasma, causing a falsely low sodium reading when measured by **flame photometry** (indirect ion-selective electrodes). - This is because the sodium concentration in the **aqueous phase** remains normal, but the total plasma volume is disproportionately high due to protein. *Severe hyperglycemia* - **Severe hyperglycemia** causes an **osmotic shift** of water from the intracellular to the extracellular compartment, diluting extracellular sodium. This can cause **translocational hyponatremia**, which is a form of pseudohyponatremia. - For every 100 mg/dL increase in glucose above normal, serum sodium typically decreases by 1.6-2.4 mEq/L. *Severe hyperlipemia* - **Severe hyperlipemia** (hypertriglyceridemia) falsely lowers the measured sodium concentration due to the large volume occupied by lipids in the plasma sample. - Similar to hyperproteinemia, this is an artifact of measurement methods that assume a constant proportion of plasma is water, causing a low reading even though sodium concentration in plasma water is normal.

Q: A 16-year-old boy presents with acute onset gross hematuria and loin pain following a recent upper respiratory tract infection. He also reports mild diarrhea. Peripheral smear examination is normal. There is no history of decreased urine output. Serum C3 levels are normal. Probable diagnosis is?

Berger's disease. ***Berger's disease*** - This presentation of **gross hematuria** and **loin pain** occurring *shortly after* an upper respiratory tract infection and mild diarrhea is highly characteristic of **IgA nephropathy** (Berger's disease) [1]. - The **normal C3 levels** help differentiate it from other conditions like PSGN, where C3 is typically low. *Post-streptococcal glomerulonephritis (PSGN)* - While PSGN can cause hematuria following an infection, it typically has a **longer latency period** (1-3 weeks after streptococcal infection) [1]. - A key distinguishing feature is **low serum C3 levels**, which are noted as normal in this case. *Microangiopathic hemolytic anemia* - This condition involves **microangiopathic hemolytic anemia**, **thrombocytopenia**, and sometimes renal failure. - The problem states a **normal peripheral smear**, ruling out the characteristic fragmented red blood cells seen in microangiopathic hemolytic anemia. *Hemolytic Uremic Syndrome (HUS)* - HUS is characterized by the triad of **microangiopathic hemolytic anemia**, **thrombocytopenia**, and **acute kidney injury**. - The presence of a **normal peripheral smear** and absence of thrombocytopenia (implied by lack of mention) make HUS unlikely.

Q: Alport syndrome - all are true except?

Cardiac hypertrophy. ***Cardiac hypertrophy*** - While patients with **Alport syndrome** can have various systemic manifestations, **cardiac hypertrophy** is not a typical or primary feature of the disease. - The disease primarily affects the **kidneys, ears, and eyes** due to defects in type IV collagen [1]. *Nerve deafness* - **Sensorineural hearing loss** is a common and characteristic extrarenal manifestation of Alport syndrome, often progressive. - This hearing impairment results from structural abnormalities in the **cochlear basement membranes** due to defective **type IV collagen** [1]. *X-linked* - The most common and severe form of Alport syndrome is **X-linked dominant**, accounting for approximately 85% of cases. - This inheritance pattern means that males are typically more severely affected than females. *Glomerulonephritis* - **Progressive glomerulonephritis** is the hallmark of Alport syndrome, leading to **hematuria, proteinuria**, and eventually **end-stage renal disease (ESRD)**. - The glomerular basement membrane (GBM) is abnormally thin and prone to splitting, which impairs its filtering function [1].

Q: A 55 year old male presents with tachypnea and mental confusion. Blood glucose 350 mg/dl, pH = 7.0. What is the most likely acid base disorder?

Metabolic acidosis. Metabolic acidosis - A **pH of 7.0** indicates significant acidemia, and **hyperglycemia (350 mg/dL)** in conjunction with clinical symptoms (tachypnea, mental confusion) strongly suggests **diabetic ketoacidosis (DKA)**, a common cause of high anion gap metabolic acidosis [1]. - Tachypnea is often a **compensatory mechanism** (Kussmaul breathing) to blow off carbon dioxide and raise pH in metabolic acidosis [1], [2]. Metabolic alkalosis - This would present with an **elevated pH (alkalemia)**, which is opposite to the patient's measured pH of 7.0 [2]. - It is typically caused by conditions like severe vomiting or diuretic use, which are not suggested by the clinical presentation [3]. Respiratory alkalosis - This condition involves a **high pH** and a **low PCO2**, often due to hyperventilation [2]. - While the patient is tachypneic, the profound acidemia (pH 7.0) contradicts a primary respiratory alkalosis. Respiratory acidosis - While leading to a low pH, respiratory acidosis is characterized by **elevated PCO2** due to hypoventilation. - The patient's **tachypnea** indicates hyperventilation, which would tend to lower PCO2, making primary respiratory acidosis unlikely.

Q: Polyuria in adults is commonly defined as urine output exceeding:

40 ml / Kg/ day. ***40 ml / Kg/ day*** - **Polyuria** is clinically defined as urine output exceeding 3 liters per 24 hours (L/day) in adults. - Converting this to a weight-based measurement for an average 75 kg adult, 3 L/day equates to approximately **40 ml/kg/day**. *50 ml/ kg / day* - This value represents a significantly higher urine output than the standard clinical definition of **polyuria**, making it an unlikely threshold. - While excessive, it would indicate a more severe and less common degree of diuresis, not the general definition. *30 ml / Kg/ day* - This value is below the typical threshold for **polyuria** and is closer to what might be considered normal or slightly elevated urine output. - Normal urine output is typically between **0.5-1 ml/kg/hour**, which translates to 12-24 ml/kg/day. *60 ml/ kg / day* - This is a substantially high urine output, indicating a profound level of **diuresis**, well beyond the standard definition of polyuria. - While possible in extreme cases, it is not the common cutoff used for defining polyuria.

Q: Which of these is the Renal feed for CKD patients?

High calorie low volume. High calorie low volume - This is the ideal feeding approach for CKD patients as it provides adequate energy without stressing the kidneys with excess fluid. - Calorie density is important to meet metabolic needs, while fluid restriction helps manage fluid balance and prevent complications like edema and hypertension. High calorie high volume - While meeting calorie needs, a high volume of fluid can worsen fluid overload, particularly in patients with impaired renal function who struggle to excrete excess water. - This approach can lead to peripheral edema, pulmonary congestion, and elevated blood pressure. Low calorie high volume - A low calorie intake fails to meet the nutritional demands of CKD patients, potentially leading to malnutrition and catabolism. - High fluid volume still poses risks of fluid overload, making this an unsuitable combination for renal patients. Low calorie low volume - Both low calorie and low volume intake can severely compromise the nutritional status of CKD patients. - This would lead to rapid weight loss, muscle wasting, and overall deterioration in health outcomes without adequate energy or fluid balance considerations.

Q: Among the following conditions, which is most likely to cause type 4 renal tubular acidosis?

Diabetic nephropathy. ***Diabetic nephropathy*** - **Diabetic nephropathy** is a common cause of **type 4 renal tubular acidosis (RTA)** due to damage to the **juxtaglomerular apparatus** affecting **renin production** and subsequent aldosterone levels. - The resulting **hypoaldosteronism** or **aldosterone resistance** [1] leads to impaired potassium and hydrogen secretion in the **distal tubules**, causing **hyperkalemia** and **metabolic acidosis**. [1] *Chronic pyelonephritis* - While chronic pyelonephritis can lead to **renal scarring** and **chronic kidney disease**, it typically does not directly cause type 4 RTA. - It is more commonly associated with a variety of tubular defects, but not specifically the **hypoaldosteronism** characteristic of type 4 RTA unless severe general renal failure is present. *Systemic lupus* - **Systemic lupus erythematosus (SLE)** can cause **lupus nephritis**, leading to various forms of kidney damage, but it is more commonly associated with **type 1 (distal)** or **type 2 (proximal) RTA**, rather than type 4. - Type 1 RTA in SLE is often due to an **autoimmune attack** on the **distal tubule's ability** to secrete hydrogen ions. *Multiple myeloma* - **Multiple myeloma** is known to cause **renal impairment** primarily through the deposition of **light chains** in the tubules, often leading to **proximal tubular dysfunction** (Fanconi syndrome) or **cast nephropathy**. - This typically results in **type 2 RTA** (proximal RTA) characterized by impaired reabsorption of bicarbonate, amino acids, and phosphate, rather than the distal tubular and aldosterone-related issues seen in type 4 RTA.

Q: Most sensitive indicator of iron deficiency in chronic kidney disease?

Transferrin saturation. ***Transferrin saturation*** - **Transferrin saturation (TSAT)** is the most sensitive indicator of iron deficiency in chronic kidney disease (CKD) because it reflects the amount of iron available for **erythropoiesis**. - A TSAT below **20%** is usually indicative of **functional iron deficiency**, even if ferritin levels appear normal due to inflammation. *TIBC* - **Total iron-binding capacity (TIBC)** measures the total amount of iron that can be bound by proteins in the blood, primarily transferrin. - While it generally increases in iron deficiency, in CKD, **inflammation** can suppress transferrin synthesis, leading to normal or even decreased TIBC, making it less reliable [2]. *Serum iron* - **Serum iron** levels fluctuate significantly throughout the day and are highly influenced by recent iron intake, making them a **poor indicator** of overall iron stores. - In CKD, systemic inflammation can also lead to **iron sequestration** within macrophages, lowering serum iron despite adequate total body iron [1]. *Serum ferritin* - **Serum ferritin** is a good indicator of overall iron stores but is often **elevated in CKD** due to inflammation, which is common in these patients. - This elevation can **mask true iron deficiency**, as ferritin can be high even when there isn't enough iron available for erythropoiesis (functional iron deficiency) [2].

Q: A CKD patient develops serum K+ 7.2 mEq/L without ECG changes. Best initial management?

Calcium gluconate. **Calcium gluconate** - **Calcium gluconate** is the best initial management for severe hyperkalemia, particularly when the potassium level is very high (above 6.5 mEq/L) even without ECG changes [1]. It acts quickly to directly stabilize the cardiac membrane by **antagonizing the effects of potassium on myocardial excitability**, thereby preventing life-threatening arrhythmias [1]. - It provides immediate cardioprotection, buying time for other therapies to shift potassium into cells or remove it from the body. *Emergency dialysis* - While **dialysis** is the most effective way to remove potassium from the body, it is typically reserved for cases of severe, refractory hyperkalemia, or when other therapies have failed [3]. - It is not the *initial* management for immediate cardiac stabilization, especially if no ECG changes are present and calcium can be administered more rapidly. *Sodium polystyrene* - **Sodium polystyrene sulfonate (Kayexalate)** is a potassium-binding resin that works in the gastrointestinal tract to exchange sodium for potassium, thus removing potassium from the body. - Its onset of action is slow (hours to days), making it inappropriate for acute, severe hyperkalemia requiring immediate intervention. *Insulin with glucose* - **Insulin with glucose** therapy promotes the intracellular shift of potassium, temporarily lowering serum potassium levels [2]. - While effective, its onset of action is typically 15-30 minutes, and it functions as a temporary measure to redistribute potassium, not to acutely stabilize the cardiac membrane, which is the primary concern when potassium is severely elevated.

Question 1

Pseudohyponatremia is found in all of the following EXCEPT:

Accepted Answer

Aldosterone excess

Answer

Extreme hyperproteinemia

Answer

Severe hyperglycemia

Answer

Severe hyperlipemia

Question 2

A 16-year-old boy presents with acute onset gross hematuria and loin pain following a recent upper respiratory tract infection. He also reports mild diarrhea. Peripheral smear examination is normal. There is no history of decreased urine output. Serum C3 levels are normal. Probable diagnosis is?

Accepted Answer

Berger's disease

Answer

Post-streptococcal glomerulonephritis (PSGN)

Answer

Microangiopathic hemolytic anemia

Answer

Hemolytic Uremic Syndrome (HUS)

Question 3

What does the term 'anion gap' refer to in clinical medicine?

Accepted Answer

Calculated difference between measured cations and measured anions.

Answer

Imbalance in serum anion levels.

Answer

Calculation used to identify metabolic acidosis.

Answer

Unmeasured ions

Question 4

Alport syndrome - all are true except?

Accepted Answer

Cardiac hypertrophy

Answer

Nerve deafness

Answer

X-linked

Answer

Glomerulonephritis

Question 5

A 55 year old male presents with tachypnea and mental confusion. Blood glucose 350 mg/dl, pH = 7.0. What is the most likely acid base disorder?

Accepted Answer

Metabolic acidosis

Answer

Metabolic alkalosis

Answer

Respiratory alkalosis

Answer

Respiratory acidosis

Question 6

Polyuria in adults is commonly defined as urine output exceeding:

Accepted Answer

40 ml / Kg/ day

Answer

50 ml/ kg / day

Answer

30 ml / Kg/ day

Answer

60 ml/ kg / day

Question 7

Which of these is the Renal feed for CKD patients?

Accepted Answer

High calorie low volume

Answer

High calorie high volume

Answer

Low calorie high volume

Answer

Low calorie low volume

Question 8

Among the following conditions, which is most likely to cause type 4 renal tubular acidosis?

Accepted Answer

Diabetic nephropathy

Answer

Chronic pyelonephritis

Answer

Systemic lupus

Answer

Multiple myeloma

Question 9

Most sensitive indicator of iron deficiency in chronic kidney disease?

Accepted Answer

Transferrin saturation

Answer

TIBC

Answer

Serum iron

Answer

Serum ferritin

Question 10

A CKD patient develops serum K+ 7.2 mEq/L without ECG changes. Best initial management?

Accepted Answer

Calcium gluconate

Answer

Emergency dialysis

Answer

Sodium polystyrene

Answer

Insulin with glucose

Nephrology — MCQs

Nephrology — MCQs

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