Diagnosis and Management of Acute Interstitial Nephritis AAFP

Questions and Answers

What is a common timeframe for drug-induced acute interstitial nephritis (AIN) to become clinically evident after starting a medication?

Two weeks or longer (correct)

Only after six months

Within one week

Immediately upon administration

Which class of medications has been implicated as an etiological factor in acute interstitial nephritis?

Analgesics

Antidepressants

Antihypertensives

Antibiotics (correct)

What may contribute to the development of drug-induced AIN aside from medication use?

Genetic predisposition

Age-related decline in renal function

Dietary factors

Local or systemic autoimmune processes (correct)

Which agent is NOT commonly associated with acute interstitial nephritis (AIN)?

Amiodarone Signup and view all the answers

What is true regarding the dose relationship of drug-induced AIN?

It is not dose-related Signup and view all the answers

Which medication is specifically mentioned as being associated with drug-induced AIN?

Indinavir Signup and view all the answers

What percentage of AIN cases typically present with the classic triad of low-grade fever, skin rash, and arthralgias?

5% Signup and view all the answers

In AIN, which symptom has the highest reported prevalence among patients?

Low-grade fever Signup and view all the answers

What characteristic feature is often evaluated through renal biopsy in cases of AIN?

Interstitial inflammation Signup and view all the answers

Which of the following is NOT a clinical finding associated with AIN?

Oliguria Signup and view all the answers

In addition to medication, which factor is often researched due to its frequency in the diagnosis of AIN?

Frequency of renal biopsy Signup and view all the answers

What type of autoantibodies may be associated with certain types of glomerulonephritis related to AIN?

Anti-tubular basement membrane (anti-TBM) autoantibodies Signup and view all the answers

What is the hallmark pathology of acute interstitial nephritis?

Infiltration of inflammatory cells Signup and view all the answers

Which medication is associated with a lower incidence of the classic triad in AIN?

Methicillin Signup and view all the answers

Of the following medications, which one is a diuretic that can be linked to AIN?

Triamterene Signup and view all the answers

What is the common clinical feature present in 15 to 20 percent of AIN cases?

Arthralgias Signup and view all the answers

What is a key indication for performing a renal biopsy in a patient with suspected acute interstitial nephritis (AIN)?

Exposure to potential offending medications Signup and view all the answers

Which of the following conditions is NOT a contraindication to renal biopsy?

Acute renal failure from AIN Signup and view all the answers

Patients who discontinue offending medications within how many weeks of AIN onset are expected to recover normal renal function?

Two weeks Signup and view all the answers

What is a typical symptom associated with acute interstitial nephritis (AIN)?

Rash, fever, arthralgias Signup and view all the answers

Which patient condition would delay the performance of a renal biopsy?

End-stage renal disease with small kidneys Signup and view all the answers

In the context of AIN, what does the acronym AIN stand for?

Acute interstitial nephritis Signup and view all the answers

What laboratory finding suggests that a patient with AIN may require a renal biopsy?

Suggestive evidence on laboratory data Signup and view all the answers

What would likely happen to a patient with AIN who does not show improvement after medication withdrawal?

Further testing for other conditions Signup and view all the answers

What is the primary reason renal biopsy may not be needed in certain patients?

Patients can improve after withdrawing triggering medications. Signup and view all the answers

Which imaging study has been proposed as a potentially useful diagnostic tool for AIN?

Gallium 67 scanning Signup and view all the answers

Who would be considered a good candidate for renal biopsy?

Patients without clinical improvement and no contraindications Signup and view all the answers

What is a characteristic finding in renal ultrasonography for patients with AIN?

Increased cortical echogenicity with possible enlarged size Signup and view all the answers

What type of clinical improvement indicates the successful withdrawal of potentially offending medications?

Increased urine output and falling creatinine level Signup and view all the answers

Why might renal ultrasonography be limited in diagnosing AIN?

It cannot differentiate AIN from other acute renal failure causes. Signup and view all the answers

In the context of AIN diagnosis, what outcome is seen in gallium 67 scans?

Positive scans are common in patients with AIN. Signup and view all the answers

What is a consideration for patients who do not improve post-medication withdrawal concerning renal biopsy?

They should have no contraindications to the procedure. Signup and view all the answers

What is the typical proteinuria level observed in acute interstitial nephritis (AIN) not associated with NSAIDs?

Usually < 1 g per 24 hours Signup and view all the answers

Which laboratory finding is most commonly associated with acute interstitial nephritis?

Presence of renal tubular epithelial cells or casts Signup and view all the answers

What is the predictive value range of urine eosinophils in diagnosing acute interstitial nephritis?

38 percent with a confidence interval of 15 to 65 percent Signup and view all the answers

Which statement is true regarding serum chemistry profile findings in patients with AIN?

Elevated BUN and creatinine indicate variable degrees of renal injury Signup and view all the answers

What is the expected result of liver function tests in patients with drug-induced acute interstitial nephritis?

Elevated serum transaminase levels Signup and view all the answers

Which laboratory finding is least likely to be diagnostically reliable in confirming or excluding acute interstitial nephritis?

Elevated urine major basic protein Signup and view all the answers

In cases of suspected AIN associated with beta-lactam antibiotics, which complete blood count finding is most indicative?

Eosinophilia Signup and view all the answers

Which electrolyte imbalance is noted in acute interstitial nephritis?

Hyperkalemia or hypokalemia Signup and view all the answers

What clinical symptoms are commonly associated with the diagnosis of acute interstitial nephritis?

Fever, rash, arthralgias, and eosinophiluria Signup and view all the answers

Study Notes

Drug-Induced Acute Interstitial Nephritis (AIN)

AIN is increasingly recognized due to the rise in drug use and renal biopsies.
Key drug classes associated with AIN include NSAIDs, diuretics, and various miscellaneous medications.
AIN can manifest 2 weeks or longer after medication initiation; not dose-related.
Symptoms may include flank pain, gross hematuria, fever, rash, and arthralgias.
Classic triad of symptoms (fever, rash, arthralgies) occurs in only 5% of AIN cases.
Urine eosinophils can be tested; positive predictive value is 38%.

Pathology and Laboratory Findings

Hallmark of AIN is inflammatory cell infiltration in the renal interstitium with edema.
Laboratory features in AIN include proteinuria, pyuria, hematuria, and elevated levels of BUN and creatinine.
Hypercholermic metabolic acidosis indicates tubulointerstitial injury.
Eosinophilia is often linked to beta-lactam antibiotic-induced AIN.

Imaging Studies and Renal Biopsy

Renal ultrasonography may show normal to enlarged kidneys with increased cortical echogenicity but cannot definitively diagnose AIN.
Gallium 67 scanning may aid diagnosis; positive scans are seen in AIN but negative in acute tubular necrosis (ATN).
Not all patients require renal biopsy; for those who do, presence of classical symptoms and no improvement post-medication withdrawal suggests biopsy.

Management and Prognosis

Immediate withdrawal of potential offending medications often leads to recovery of normal renal function within weeks.
Patients who cease offending drugs within two weeks of AIN onset are more likely to experience significant recovery.
Renal biopsy is contraindicated in cases of bleeding diathesis, solitary kidney, or severe hypertension.
Supportive management can be effective for patients unlikely to benefit from a biopsy.

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Description

This quiz examines the causes and effects of drug-induced acute interstitial nephropathy (AIN). It covers the mechanisms by which medications can cause kidney injury and the broader implications for renal health. Enhance your understanding of nephrology and the impacts of pharmaceuticals on the kidneys.