Nephrology Practice Questions

Q: A patient presents with acute renal failure (ARF) and complete anuria, with a normal ultrasound of the kidneys. Which investigation will provide the best initial information regarding renal function?

DTPA Scan (Radiorenogram). DTPA Scan (Radiorenogram) - A DTPA scan can assess renal perfusion and glomerular filtration rate (GFR), providing crucial information about the functional status of the kidneys, particularly in cases of anuria [1]. - In the context of anuria with a normal ultrasound, it helps differentiate between pre-renal (poor perfusion), post-renal (if obstruction was missed), or intrinsic renal failure by evaluating blood flow and tracer uptake [1]. Serum Creatinine - While serum creatinine is a marker of renal function, it reflects the current state and doesn't provide real-time or dynamic information about renal blood flow or GFR at the onset of anuria [2]. - In acute renal failure, particularly with anuria, creatinine levels can rise rapidly, but assessing the cause and degree of functional impairment beyond simple filtration requires more advanced imaging. Urine Output Assessment - The patient is already presenting with complete anuria, meaning there is no urine output, rendering this assessment uninformative for further diagnostic steps. - While typically a crucial initial indicator, in this specific scenario, it only confirms the clinical presentation and does not provide insight into the underlying etiology of the anuria. Renal Biopsy - A renal biopsy is an invasive procedure primarily used for definitive diagnosis of intrinsic renal diseases and is not a first-line investigation for immediate assessment of renal function in acute anuria [2]. - It would typically be considered after non-invasive tests have failed to provide a diagnosis or if a specific intrinsic renal disease is strongly suspected and requires histological confirmation [2].

Q: Hyperkalemia without ECG changes may be treated with all except one of the following medications:

Atenolol. ***Atenolol*** - **Atenolol** is a beta-blocker that does not play a direct role in the acute management of hyperkalemia. In fact, beta-blockers can sometimes **worsen hyperkalemia** by impairing cellular potassium uptake [3]. - Its primary use is for conditions like hypertension or angina, and it has no mechanism to significantly lower serum potassium levels or stabilize cardiac membranes in hyperkalemia. *Calcium gluconate* - **Calcium gluconate** is used to stabilize the cardiac membrane and prevent arrhythmias in hyperkalemia, particularly when ECG changes are present [1]. - While it doesn't lower serum potassium levels directly, it is crucial for **cardioprotection**, and its absence here implies the question is about potassium-lowering agents. *Na bicarbonate* - **Sodium bicarbonate** can be used to shift potassium intracellularly, particularly in patients with **metabolic acidosis**. - It increases intracellular pH, which promotes the movement of potassium into cells, thus lowering extracellular potassium. *Insulin with dextrose* - **Insulin with dextrose** is a common and effective treatment for hyperkalemia, as insulin promotes the uptake of potassium into cells. - Dextrose is administered concurrently to prevent **hypoglycemia**, which would otherwise occur due to the insulin [2].

Q: What is a common electrolyte disturbance seen in chronic renal failure?

Hyperkalemia. **Hyperkalemia** - As **glomerular filtration rate (GFR)** decreases in chronic renal failure, the kidneys' ability to excrete potassium is significantly impaired, leading to its accumulation [1]. - This is a common and potentially life-threatening complication due to its effects on **cardiac rhythm** [1]. *Hypercalcemia* - While possible in some renal conditions, **hypercalcemia** is not a typical electrolyte disturbance seen primarily due to the loss of kidney function; instead, **hypocalcemia** is more characteristic [2]. - Renal failure often leads to impaired vitamin D activation and phosphate retention, which tend to lower, not raise, serum calcium [2]. *Hypocalcemia* - Although **hypocalcemia** is also a common feature of chronic renal failure, the question asks for "a common electrolyte disturbance" and **hyperkalemia** is often considered more immediately life-threatening and directly linked to impaired excretion. - It results from decreased production of **1,25-dihydroxyvitamin D** by the kidneys and phosphate retention, which binds to calcium [2]. *Hyperphosphatemia* - **Hyperphosphatemia** is indeed a very common electrolyte disturbance in chronic renal failure, resulting from the kidney's inability to excrete phosphate [2]. - However, the options present multiple common disturbances, and **hyperkalemia** is often highlighted due to its acute danger.

Question 1

A patient presents with acute renal failure (ARF) and complete anuria, with a normal ultrasound of the kidneys. Which investigation will provide the best initial information regarding renal function?

Accepted Answer

DTPA Scan (Radiorenogram)

Answer

Serum Creatinine

Answer

Urine Output Assessment

Answer

Renal Biopsy

Question 2

Hyperkalemia without ECG changes may be treated with all except one of the following medications:

Accepted Answer

Atenolol

Answer

Na bicarbonate

Answer

Insulin with dextrose

Answer

Calcium gluconate

Question 3

What is a common electrolyte disturbance seen in chronic renal failure?

Accepted Answer

Hyperkalemia

Answer

Hypocalcemia

Answer

Hypercalcemia

Answer

Hyperphosphatemia

Nephrology — MCQs

Nephrology — MCQs

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