QuestionSBA
QuestionChoice
Ramipril is an ACE inhibitor which is a nephrotoxic. It may cause an increase in serum creatinine but this is because of a **true** decrease in glomerular filtration rate
31801
d
Ramipril
QuestionChoice
Statins may cause rhabdomyolysis which leads to an increased creatinine level but this would be due to a **true** decrease in glomerular filtration rate
31802
e
Atorvastatin
QuestionChoice
Bisoprolol is not a nephrotoxic and has no effect on serum creatinine
31800
c
Bisoprolol
QuestionChoice
Trimethoprim inhibits tubular creatinine secretion, leading to an increase in serum creatinine independent of the true glomerular filtration rate (GFR). This leads to a falsely low eGFR as creatinine concentration is used in the calculation of GFR
31798
a
Trimethoprim
QuestionChoice
Nitrofurantoin is not a nephrotoxic itself and will not cause an increase in serum creatinine, however, it is contraindicated in those with renal impairment due to reduced renal elimination of the antibiotic in these patients
31799
b
Nitrofurantoin
QuestionComment
Fun fact trimethoprim has a chemical structure very close to the potassium sparing diuretic amiloride and is also well known to cause a rise in potassium in addition to falsely elevated creatinine (esp when used with ACEi etc)
22721
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;-;
QuestionComment
So just to confirm she has new onset AKI that is causing her confusion/delirium (explained by the high creatine) and the low eGFR (that is usually indicative of CKD which she has no history of) is caused by the trimethoprim?
23442
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Lateral Kinase
QuestionComment
could someone please explain the "true rise" bit for ramipril? I dont get it 
41339
QuestionComment
By reducing angiotensin II levels, ramipril dilates the efferent arteriole. This lowers the pressure within the glomerulus, which can reduce the glomerular filtration rate (GFR). As a result, waste products like creatinine may not be filtered out as efficiently, leading to an increase in blood creatinine levels.
54697
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Wilsons CT
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Neoplasia Nightshift
Concept
Chapter
# Pathophysiology

Trimethoprim can lead to a transient rise in creatinine levels by reducing the creatinine excretion of the kidneys. 

This does NOT reflect the actual GFR and therefore this phenomenon is not reflective of an Acute kidney injury but rather the calculated eGFR due to a transient rise in Creatinine.
1784
1968
Trimethoprim and renal function
Topic
33
Nephrology
6360
Trimethoprim can falsely lower estimated glomerular filtration rate (eGFR) by inhibiting tubular creatinine secretion, affecting serum creatinine levels.
A 60-year-old lady presents to the emergency department with confusion. She has the following blood tests:


||||
|---------------------------|:-------:|--------------------|
|Sodium|136 mmol/L|135 - 145|
|Potassium|4 mmol/L|3.5 - 5.3|
|Urea|6 mmol/L|2.5 - 7.8|
|Creatinine|300 µmol/L|60 - 120|
|eGFR|15 mL/min/1.73m<sup>2</sup>|> 60|


Her previous blood tests from 2 months ago suggest that her baseline creatinine is approximately 70umol/L.


There is no information on the computer system about her medications but you find the following medications in her bag: trimethoprim, nitrofurantoin, bisoprolol, ramipril, and atorvastatin.


Which of the following medications would lead to a falsely low estimated glomerular filtration rate (eGFR)?
a