Eosinophiluria--a new method of detection and definition of the clinical spectrum

Urinalysis: Interpretation and Clinical Correlations

Urinalysis is a widely used diagnostic tool to assist clinicians in determining the etiology of various acute or chronic pathologies. Primary care, general internal medicine, and family medicine clinicians should be adept at identifying indications for urinalyses, in addition to appropriately interpreting their results. In this article, we provide an overview of urinalysis for non-nephrologists.

Clinical Characteristics of Children With Acute Tubulointerstitial Nephritis: A Single-Center Experience

OBJECTIVE

Acute tubulointerstitial nephritis (ATIN) is an infiltration of the kidney interstitium with inflammatory cells. Medications are most frequently blamed for the etiology. Patients may present with non-specific signs and symptoms. Therefore, the diagnosis of ATIN is often delayed. In this study, clinical characteristics, treatment protocols, and outcomes of children diagnosed with ATIN were presented.

METHODS

This is a retrospective study based on the data of 18 patients diagnosed with ATIN between 2017 and 2022 at Gazi University. Patients were divided into two groups: steroid-treated (n=13) and non-steroid-treated (n=5). Clinical features and laboratory evaluations were compared between the groups.

RESULTS

The mean age of the patients was 14.4±2.6 years, and the great majority were girls (88.9%, n=16). ATIN was mostly medication-related (n=17, 94.4%). Steroids were started in one-third of patients using non-steroidal anti-inflammatory drugs. Steroids were started in 45.4% of the patients with eosinophilia, 75% of those with pyuria, 66.6% of those with hematuria, and half of the patients with increased kidney echogenicity. The kidney functions returned to normal ranges in all patients. In steroid-treated patients, although recovery times for serum creatinine were longer (7.2±2.5 vs. 71.2±100.7 days), blood eosinophil count reached normal values more rapidly (5.4±2.3 vs. 3.1±1.0 days).

CONCLUSION

ATIN can be associated with diverse clinical presentations. The first and most important step of treatment is to discontinue the medication responsible for the etiology. Steroid treatment improves eosinophilia more rapidly. However, randomized controlled studies are needed to determine further treatment steps and establish a more definite treatment protocol.

Bland Urine Sediment in a Child with Acute Kidney Injury

Tubulointerstitial nephritis (TIN) or acute interstitial nephritis (AIN) is a renal lesion characterized by inflammatory infiltrate limited to the renal interstitium and tubules. Three-fourths of the cases are drug induced, other causes being systemic and autoimmune diseases, and infections. Various drugs have been implicated, the most common being antibiotics such as β-lactams. Cephalosporins causing AIN have been reported uncommonly, particularly in children. Although renal biopsy confirms the diagnosis, urinalysis provides pertinent diagnostic clues against the backdrop of the clinico-laboratory profile. The presence of white blood cells, white cell casts, and red blood cells in urine sediment have been described in literature. However, a relatively normal urinalysis may be present in some cases and may pose a diagnostic challenge. We present a case of ceftriaxone-induced AIN in a child with bland urine sediment at initial presentation. To the best of our knowledge, this is the first report of ceftriaxone-induced AIN in the pediatric age group.

New Biomarkers in Acute Tubulointerstitial Nephritis: A Novel Approach to a Classic Condition

Acute tubulointerstitial nephritis (ATIN) is an immunomediated cause of acute kidney injury. The prevalence of ATIN among the causes of acute kidney injury (AKI) is not negligible, especially those cases related to certain drugs. To date, there is a lack of reliable non-invasive diagnostic and follow-up markers. The gold standard for diagnosis is kidney biopsy, which shows a pattern of tubulointerstitial leukocyte infiltrate. The urinalysis findings can aid in the diagnosis but are no longer considered sensitive or specific. Atthe present time, there is a rising attentiveness tofinding trustworthy biomarkers of the disease, with special focus in urinary cytokines and chemokines that may reflect kidney local inflammation. Cell-based tests are of notable interest to identify the exact drug involved in hypersensitivity reactions to drugs, manifesting as ATIN. Certain single-nucleotide polymorphisms in HLA or cytokine genes may confer susceptibility to the disease according to pathophysiological basis. In this review, we aim to critically examine and summarize the available evidence on this topic.

Diagnosing acute interstitial nephritis: considerations for clinicians

Acute interstitial nephritis (AIN) is a common cause of acute kidney injury (AKI), particularly in hospitalized patients. It can be difficult for clinicians to differentiate between AIN and other common causes of AKI, most notably acute tubular necrosis (ATN) and prerenal injury. Clinicians often struggle with the clinical history and laboratory data available to definitively diagnose AIN. Sometimes they diagnose ATN or AIN based on these flawed data. Thus it is important that clinicians be familiar with the utility of commonly ordered tests used to aid in the diagnosis. Unfortunately, no single test performs particularly well on its own, and until a biomarker is rigorously shown to be diagnostic of AIN, most patients require a kidney biopsy to definitively establish the diagnosis and direct further management.

Acute and Chronic Tubulointerstitial Nephritis of Rheumatic Causes

Tubulointerstitial nephritis (TIN) is the second most common cause of acute intrinsic kidney injury after acute tubular necrosis. Although drug-induced forms of TIN represent the vast majority, rheumatic disease is another common cause and often underdiagnosed. Early diagnosis of acute interstitial nephritis and prompt withdrawal of the culprit medication or a correct treatment can avoid chronic damage and progressive chronic kidney disease. This review highlights the recent updates, clinical features, and treatment in TIN in autoimmune rheumatic disease.

Clinical Approach to Diagnosing Acute and Chronic Tubulointerstitial Disease

Tubulointerstitial diseases are a relatively common cause of acute and/or chronic kidney disease. Acute tubulointerstitial nephritis (ATIN) most commonly develops in patients exposed to various medications; however, it can occur from infections, autoimmune and systemic diseases, environmental exposures, and some idiopathic causes. Chronic tubulointerstitial nephritis may develop in patients with previous ATIN or may be the initial manifestation of an autoimmune, systemic, environmental, or metabolic process. It can be challenging for clinicians to differentiate the various causes of acute and chronic kidney disease. In particular, distinguishing ATIN from other causes of acute kidney injury, such as acute tubular necrosis or a rapidly progressive glomerulonephritis, is important as treatment and prognosis are often quite different. To this end, clinicians use clinical assessment, certain laboratory data, and various imaging tests to make a diagnosis. Unfortunately, most of these tests are insufficient for this purpose. As a result, kidney biopsy is often required to accurately diagnose ATIN and guide management. For chronic tubulointerstitial nephritis, kidney biopsy is needed less often as available therapies for this entity, with a few exceptions, are limited and primarily supportive.

Measuring eosinophiluria, urinary eosinophil cationic protein and urinary interleukin-5 in patients with Lupus Nephritis

BACKGROUND

Urine is increasingly becoming an attractive biological fluid in clinical practice due to being an easily obtained, non-invasive sampling method, containing proteins and peptides. The aim of this study was to investigate eosinophiluria, urinary eosinophil cationic protein (uECP) and urinary IL-5 (uIL-5) in patients with Lupus Nephritis.

METHODS

Seventy-four patients with SLE-20 with clinical and laboratory evidence of lupus nephritis (LN group) and 54 without evidence of renal involvement (non-LN group)-were analyzed regarding eosinophiluria, uECP and uIL-5. Eosinophiluria was observed by Hansel's stain, ECP by fluoroenzymeimmunoassay and uIL-5 by quantitative sandwich enzyme immunoassay. Both uECP and urinary IL-5 (uIL-5) were corrected by urinary creatinine. Eosinophiluria and uECP were compared with glomerular erythrocyturia, protein/creatinine ratio (Pr/Cr ratio), serum creatinine, estimated glomerular filtration rate (eGFR), anti-double-stranded DNA (anti-dsDNA), serum levels of complement (C3 and C4), uIL-5/Cr ratio, and SLE disease activity index.

RESULTS

Patients of the LN group had higher eosinophiluria, uECP, uECP/Cr ratio levels, and uIL-5 than patients of the non-LN group (p<0.001 for all). These variables showed a statistically significant correlation with glomerular erythrocyturia, casts, Pr/Cr ratio, serum creatinine, eGFR, anti-dsDNA, uIL-5/Cr, and SLE disease activity index (all p<0.05).

CONCLUSION

These results provide evidence of increased urinary eosinophils, ECP and IL-5 in patients with SLE and LN; uECP/Cr ratio showed better correlation with markers of renal function and SLE disease activity.

Diagnosing drug-induced AIN in the hospitalized patient: a challenge for the clinician

Drug-induced acute interstitial nephritis (AIN) is a relatively common cause of hospital-acquired acute kidney injury (AKI). While prerenal AKI and acute tubular necrosis (ATN) are the most common forms of AKI in the hospital, AIN is likely the next most common. Clinicians must differentiate the various causes of hospital-induced AKI; however, it is often difficult to distinguish AIN from ATN in such patients. While standardized criteria are now used to classify AKI into stages of severity, they do not permit differentiation of the various types of AKI. This is not a minor point, as these different AKI types often require different therapeutic interventions. Clinicians assess and differentiate AIN from these other AKI causes by utilizing clinical assessment, various imaging tests, and certain laboratory data. Gallium scintigraphy has been employed with mixed results. While a few serum tests, such as eosinophilia may be helpful, examination of the urine with tests such as dipstick urinalysis, urine chemistries, urine eosinophils, and urine microscopy are primarily utilized. Unfortunately, these tools are not always sufficient to definitively clinch the diagnosis, making it a challenging task for the clinician. As a result, kidney biopsy is often required to accurately diagnose AIN and guide management.

Acute Interstitial Nephritis: Etiology, Pathogenesis, Diagnosis, Treatment and Prognosis

Acute interstitial nephritis (AIN) is an important and common cause of acute kidney injury, particularly in hospitalized patients. The classic presentation of AIN includes fever, rash, arthralgias, eosinophilia, and acute kidney injury. While renal biopsy is considered the gold standard for diagnosis, the clinical presentation of fever and rash along with laboratory evidence of peripheral blood eosinophilia, eosinophiluria, and low-grade proteinuria strongly suggest the diagnosis. Histologically, interstitial inflammation with interstitial edema and tubulitis is the hallmark of interstitial nephritis. The most common causative factors are drugs, infections, and certain immune-mediated disorders. Discontinuation of the offending agent is considered the mainstay of therapy while the use of corticosteroids to hasten renal recovery may be beneficial. The role of interstitial nephritis in the pathogenesis of chronic kidney disease and end-stage renal disease is increasingly recognized, further emphasizing the importance of its early diagnosis and timely treatment.

Utility of urine eosinophils in the diagnosis of acute interstitial nephritis

BACKGROUND AND OBJECTIVES

Urine eosinophils (UEs) have been shown to correlate with acute interstitial nephritis (AIN) but the four largest series that investigated the test characteristics did not use kidney biopsy as the gold standard.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This is a retrospective study of adult patients with biopsy-proven diagnoses and UE tests performed from 1994 to 2011. UEs were tested using Hansel's stain. Both 1% and 5% UE cutoffs were compared.

RESULTS

This study identified 566 patients with both a UE test and a native kidney biopsy performed within a week of each other. Of these patients, 322 were men and the mean age was 59 years. There were 467 patients with pyuria, defined as at least one white cell per high-power field. There were 91 patients with AIN (80% was drug induced). A variety of kidney diseases had UEs. Using a 1% UE cutoff, the comparison of all patients with AIN to those with all other diagnoses showed 30.8% sensitivity and 68.2% specificity, giving positive and negative likelihood ratios of 0.97 and 1.01, respectively. Given this study's 16% prevalence of AIN, the positive and negative predictive values were 15.6% and 83.7%, respectively. At the 5% UE cutoff, sensitivity declined, but specificity improved. The presence of pyuria improved the sensitivity somewhat, with a decrease in specificity. UEs were no better at distinguishing AIN from acute tubular necrosis compared with other kidney diseases.

CONCLUSIONS

UEs were found in a variety of kidney diseases besides AIN. At the commonly used 1% UE cutoff, the test does not shift pretest probability of AIN in any direction. Even at a 5% cutoff, UEs performed poorly in distinguishing AIN from acute tubular necrosis or other kidney diseases.

AKI in a hospitalized patient with cellulitis

AKI occurs commonly in hospitalized patients with multiple comorbidities. In this Attending Rounds, a woman with AKI in the setting of an infection, use of antibiotics and other medications, bacteremia, and hypotension is considered. Such patients lead to a broad differential diagnosis for AKI including prerenal AKI, acute tubular injury/acute tubular necrosis, infection-related GN, and drug-induced acute interstitial nephritis. The roles of an accurate history, physical examination, laboratory data, and kidney biopsy are highlighted in establishing the correct diagnosis in such patients.

Eosinophiluria is common among patients after ileal conduit surgery

BACKGROUND

Urinary eosinophils are used to screen for acute interstitial nephritis (AIN). Technologists in the Mayo Clinic Renal Laboratory observed that patients with urinary diversion surgeries frequently had an unusually high number of urinary eosinophils.

METHODS

Urine samples from three cohorts of patients were studied (n=20 each): (1) urinalysis samples with a "stoma" source indicating a previous ileal conduit surgery; (2) urine samples clinically submitted for eosinophil quantification; (3) randomly selected urinalysis samples with a minimum of 1-3 white cells per high-powered field. Urinary eosinophils were quantified after Hansel staining as the mean of independent counts by four blinded technologists.

RESULTS

Eosinophils composed an average 19% of the urinary white cells in the stoma group, even though none had a clinical suspicion of AIN. In contrast, only 3.5% and 4.6% of the urinary white cells were eosinophils among patients with clinically-ordered eosinophiluria testing and in a random sample of patients with pyuria, respectively (p<0.001 for each group vs. the stoma patients). Importantly, 90% (18 out of 20) of the stoma patients had >5% eosinophils, meeting the criterion for a positive test.

CONCLUSIONS

Patients with a previous ileal conduit surgery have markedly elevated urinary eosinophils, far in excess of typical patients with pyuria or those with clinically-ordered eosinophiluria testing. Therefore, urinary eosinophils are not a useful screen for AIN in patients after ileal conduit surgery.

Drug-induced acute interstitial nephritis

Acute interstitial nephritis (AIN) is a common cause of acute kidney injury. Many etiologies of AIN have been recognized--including allergic/drug-induced, infectious, autoimmune/systemic, and idiopathic forms of disease. The most common etiology of AIN is drug-induced disease, which is thought to underlie 60-70% of cases. Multiple agents from many different classes of drugs can cause AIN, and the clinical presentation and laboratory findings vary according to the class of drug involved. AIN is characterized by interstitial inflammation, tubulitis, edema, and in some cases, eventual interstitial fibrosis. A definitive diagnosis of AIN can be established only by kidney biopsy. Noninvasive tests such as (67)gallium scintigraphy and testing for eosinophiluria have limited diagnostic utility. The mainstay of therapy for drug-induced AIN is timely discontinuation of the causative agent. Although the benefits of corticosteroid therapy remain unproven, they do appear to have a positive effect in some patients with drug-induced AIN, especially when treatment is initiated early in the course of the disease. In general, the prognosis for drug-induced AIN is good, and at least partial recovery of kidney function is normally observed. Early recognition is crucial because patients can ultimately develop chronic kidney disease.

Acute kidney injury in the elderly

The aging kidney undergoes several important anatomic and physiologic changes that increase the risk of acute kidney injury (formerly acute renal failure) in the elderly. This article reviews these changes and discusses the diagnoses frequently encountered in the elderly patient with acute kidney injury. The incidence, staging, evaluation, management, and prognosis of acute kidney injury are also examined with special focus given to older adults.

[Interstitial nephritis]

Drugs such as antibiotics, non-steroidal anti-inflammatory drugs and proton pump inhibitors, infections and systemic diseases can trigger interstitial nephritis. The clinical outcome varies from asymptomatic progression to acute kidney injury. Interstitial nephritis often leads to characteristic and detectable partial tubular disorders such as tubular proteinuria (alpha(1)-microglobulin), phosphaturia with hypophosphatemia, aminoaciduria, diminished H(+) secretion with metabolic acidosis with inadequate high urinary pH, glucosuria and salt loss. The main principle of treatment is avoidance of the inducing agent. In addition corticosteroids have been proven usable after exclusion of an infection so that a good prognosis can be expected for acute nephritis in the majority of cases. In chronic forms the interstitial nephritis involves the glomeruli as well as potentially resulting in end-stage renal failure in the long run. Supportive therapies are then required in the sense of chronic renal failure in order to prevent further functional loss up to end-stage renal disease.

Acute kidney injury in the intensive care unit

Acute kidney injury (AKI) is common among critically ill patients and results in increased mortality in this population. This review focuses on the diagnosis and management of AKI. The authors first explore new aspects of diagnosis, including new criteria that take into account even modest changes in renal function, and the development of novel biomarkers to allow earlier identification and better differential diagnosis of AKI. The authors also explore the available data on choice of dialysis modality and dialysis dose for the treatment of AKI, as well as the breakthrough development of the bioartificial kidney. Last, the authors review co-interventions that may have relevance to prognosis of AKI, such as intensive insulin therapy and the use of erythropoietin.

Clinical Use and Pathogenetic Basis of Laboratory Tests for the Evaluation of Primary Arterial Hypertension

This review focuses on the laboratory biochemical tests that are useful in the diagnostic approach to the hypertensive patient. A "minimal" diagnostic laboratory work-up, including a small number of tests that are simple and relatively inexpensive, is first described. Because these tests provide basic information on the presence of major cardiovascular (CV) risk factors and target organ damage, and might give some clues to the presence of a secondary form of hypertension (HT), they should be performed on all patients presenting with HT. Other tests that are aimed at assessing the overall CV risk, a major determinant of prognosis that dictates the therapeutic strategy in the individual HT patient, are then discussed. They allow identification of major CV risk factors and associated clinical conditions which, if present, lead to a substantial change of therapeutic strategy. The role of C-reactive protein as a marker of atherosclerosis and its predictive value for CV events are also discussed. Finally, a section is devoted to tests that are currently confined to research purposes, such as markers of endothelial function including endothelin-1, homocysteine and genetic analysis.

Critical issues in nephrology

Renal and electrolyte problems are common in patients in the ICU. Several advances that occurred in the recent past have been incorporated in the diagnosis and management of these disorders and were reviewed in this article. Unfortunately, many important questions remain unanswered, especially in the area of ARF, where new therapies are anxiously awaited to make the transition from bench to bedside. Better studies are sorely needed to define the best approach to dialysis in patients who have ARF.

Perioperative care of the patient with renal failure

Preventing postoperative ARF, especially in subjects with pre-existing chronic kidney disease, and caring for ESRD patients undergoing surgery are challenging and best accomplished by a team comprised of primary care physician, nephrologist, cardiologist, surgeon, anesthesiologist, endocrinologist, and nutritionist. Elimination of risk factors for ARF whenever possible, as well as early diagnosis, may improve the outcome of this devastating illness. Drugs capable of preventing or changing the course of postoperative ARF may be available soon. For uremic patients, a comprehensive approach is necessary to minimize morbidity and mortality imposed by numerous comorbid conditions.

Expression of oncostatin M in hematopoietic organs

Murine oncostatin M (OSM), a member of the interleukin-6 (IL-6) -related cytokine subfamily, stimulates definitive hematopoiesis and liver development. The OSM gene was cloned as a cytokine-inducible early response gene in some hematopoietic cell lines. In this study, we performed in situ hybridization to examine the tissue distribution of cells expressing OSM mRNA in the developing and the adult mice. Its gene expression was seen in hematopoietic cells of developing liver from 11.5 days postcoitum (dpc), and persisted to the neonates. From 17.5 dpc, OSM mRNA-positive cells were found in other hematopoietic organs, including bone marrow, thymus, and spleen. The highest levels of gene expression were observed in the adult bone marrow. Most OSM-expressing cells expressed IL-5 receptor alpha subunit, a marker for eosinophil lineage. In addition, some positive cells expressed neutrophil elastase, which was used as a polymorphonuclear neutrophil (PMN) marker. After birth, OSM mRNA was expressed in tissue eosinophils in nonhematopoietic organs, including small intestine, lung, and skin. Our data revealed that eosinophil progenitors and eosinophils as well as PMNs are also an important cellular source of OSM in mice.

Establishment of animal model of antigen-specific T lymphocyte recruitment into nasal mucosa

DO11.10 transgenic mice, expressing an ovalbumin (OVA)-specific alphabeta T-cell receptor (TCR), have been used as a model of various immune diseases associated with T lymphocytes. Some studies of immunoresponse in lung have involved adoptive transfer of DO11.10 mice. As of yet, however, there have been no studies of the adoptive transfer model in the upper airway. The purpose of this study was to establish an animal model to clarify the recruitment mechanism and the roles of Th2 cells in allergic rhinitis. In accordance with the adoptive transfer system, we generated Th0, Th1 and Th2 cells from DO11.10 mice and transferred them into wild type BALB/c mice. Following nasal OVA challenge to DO11.10 mice or to the BALB/c mice into which antigen-specific Th2 cells had been transferred, the number of local antigen-specific TCR-positive cells accompanying the local eosinophilia had significantly increased. However, nasal OVA challenge to BALB/c mice into which antigen-specific Th0 or Th1 cells were transferred failed to increase the number of local OVA-specific TCR positive cells. These observations suggest that an antigen-specific homing mechanism of Th2 cells may exist in nasal mucosa. Analysis of this model will assist in the development of new therapeutic strategy, which targets Th2 cells in allergic rhinitis.

Nephrotoxicity and hepatotoxicity of histamine H2 receptor antagonists

The extensive use of selective histamine H2 receptor antagonists provides a unique opportunity to describe very rare adverse drug reactions. Although mild elevation of serum creatinine level following the administration of cimetidine is relatively common, acute interstitial nephritis (AIN) is a rare hypersensitivity reaction. There have been 25 published reports of AIN associated with H2 antagonist therapy and we also identified 16 cases from the Australian Adverse Drug Reaction Advisory Committee (ADRAC) database. AIN was reported most commonly following cimetidine administration. AIN was supported by renal biopsy in 28 patients and by rechallenge in 6. H2 antagonist-induced AIN was more commonly reported in men older than 50 years. In the majority of cases the onset was within 2 weeks of initiation of therapy (1 day to 11 months). The clinical manifestations were nonspecific including sterile pyuria, elevated erythrocyte sedimentation rate, fatigue, proteinuria and leucocytosis whereas rash, arthralgia and flank pain were rarely reported. There were 170 cases of hepatotoxicity following H2 antagonist administration reported to ADRAC. These were more common following ranitidine and included cholestatic, hepatocellular and mixed reactions. Hepatotoxicity was proven following liver biopsy in several cases published in the literature and in 15 cases reported to ADRAC. Hepatotoxicity recurred upon rechallenge in 6 cases. Generally, renal and hepatic adverse effects resolved quickly after cessation of H2 antagonist therapy and did not require specific treatment. Nephrotoxicity and hepatotoxicity following administration of an H2 antagonist is rare and a high index of suspicion is necessary for early detection. Now that many H2 antagonists are available over the counter, awareness of these conditions and early detection with cessation of H2 antagonist therapy would appear paramount.

Latent adenoviral infection modifies the steroid response in allergic lung inflammation

BACKGROUND

Steroid-resistant asthma develops after adenoviral bronchiolitis.

OBJECTIVE

We sought to determine the effect of steroids on allergic lung inflammation in the presence of latent adenoviral infection.

METHODS

Guinea pigs with latent adenoviral (n = 12) or sham (n = 12) infections were sensitized and challenged with ovalbumin (OA) or sham sensitized and challenged with saline solution. The effect of steroids (20 mg/kg administered intraperitoneally) on OA-induced lung inflammation was examined by using quantitative histology as the outcome measure.

RESULTS

Latent adenoviral infection increased CD8(+) cells in the airway wall and CD8(+) cells, macrophages, B cells, and CD4(+) cells in the lung parenchyma. Ovalbumin challenge, on the other hand, increased eosinophils, macrophages, B cells, and CD4(+) cells in both the airway wall and lung parenchyma independent of the effect of latent adenoviral infection. In the sham-infected groups steroid treatment caused the expected reduction in the eosinophilic infiltrate induced by OA challenge in the airways without affecting the other cells. In the presence of both latent adenoviral infection and OA challenge, steroid treatment had no effect on allergen-induced eosinophilia but reduced CD8(+) cells in the airways and CD8(+) cells, CD4(+) cells, and B cells in the parenchyma.

CONCLUSION

Latent adenoviral infection and OA challenge result in different types of lung inflammation, and the presence of latent adenoviral infection causes OA-induced eosinophilic airway inflammation to become steroid resistant.

Urinary microscopy as seen by nephrologists

Urinary microscopy is a diagnostic tool which is largely used by nephrologists. In the opinion of the authors the best results can be achieved when all the aspects concerning this test are properly taken into account. Thus, from the methodological point of view, proper patient guidance, proper urine collection and handling, adequate microscopic equipment, and knowledge of the factors which can influence the results are all necessary. All the elements of clinical importance have to be known, namely, erythrocytes (with their morphological subtypes), leukocytes, tubular cells, uroepithelial cells (both superficial and deep), lipids, casts, crystals, and microorganisms. Then, the urinary findings have to be interpreted and, whenever possible, also combined into urinary profiles (e.g., the nephritic sediment, the nephrotic sediment). This, combined with other laboratory tests, the pathologic findings, and the clinical data, allows for the definition and management of urinary tract diseases.

Drug-induced acute interstitial nephritis

Acute interstitial nephritis (AIN) is a form of inflammatory renal disease affecting predominantly the tubules and the interstitium. Drugs, particularly beta-lactam antibiotics and non-steroidal anti-inflammatory drugs, are currently the most common causes. The pathogenesis of drug-induced AIN is complex but there is good clinical evidence for an immune-mediated reaction. Clinical findings may be variable depending on the drug involved and the individual response. Most patients recover from the acute renal failure; however, in older patients or in patients with pre-existing renal insufficiency the recovery of renal function may be incomplete.

Evaluation of urinary markers in acute renal failure

Acute renal failure continues to be a difficult clinical problem despite developments in dialysis and critical care. Diagnosis of the etiology frequently determines treatment. Urinalysis remains an essential diagnostic tool in the approach to acute renal failure, particularly with the current emphasis on cost-containment and evidence-based medicine. This review focuses on some of the characteristic features in the urinalysis found in different forms of acute renal failure, current developments into the molecular basis for these urinary abnormalities, and new markers on the horizon.

Probable diltiazem-induced acute interstitial nephritis

OBJECTIVE

To describe a case of acute interstitial nephritis (AIN) probably related to administration of diltiazem.

CASE SUMMARY

A 53-year-old white man presented to the hospital experiencing abdominal pain radiating to both renal fossae, as well as dysuria. Diltiazem and atenolol had been prescribed to treat an episode of precordial pain associated with effort. An erythematous maculopapular rash developed approximately 2 hours after administration of a single dose of diltiazem, and acute renal failure, associated with elevated liver function test results, developed 6 days later.

DISCUSSION

To the best of our knowledge, this is the third reported case of acute renal failure believed to be induced by diltiazem. In all cases, there was an obvious temporal relationship between administration of diltiazem and the onset of acute renal failure. Previous reports failed to discuss a probable pathogenic mechanism. AIN is the most likely etiology of acute renal failure in our patient. Favorable resolution with no relapse, the presence of the skin rash, and the liver sequelae suggest a common immunoallergic mechanism.

CONCLUSIONS

Healthcare professionals should consider diltiazem-induced AIN in the differential diagnosis of a patient taking diltiazem who develops acute renal failure.

Wegener's granulomatosis in a patient with apparent drug-induced acute interstitial nephritis

We describe a patient whose clinical presentation was suggestive of drug-induced acute interstitial nephritis (AIN). A renal biopsy and serologic testing led instead to the diagnosis of Wegener's granulomatosis (WG) with necrotizing crescentic glomerulonephritis. Treatment with corticosteroids and cyclophosphamide resulted initially in complete recovery of renal function, and an exacerbation of acute renal failure after doses of these agents had been tapered responded to resumption of the original regimen. We report this case to emphasize the potentially identical presentations of AIN and WG. Since the two conditions are treated differently, we suggest that the diagnosis of AIN should be accepted only after biopsy confirmation.

Eosinophilic leukocyte accumulation during vagally induced bronchoconstriction

Eosinophilic leukocytes (eosinophils) are important effector cells in allergic inflammatory diseases such as asthma, in which significant accumulation of these cells is observed in the bronchial mucosa. However, there is little information about the relationships between bronchoconstriction and accumulation of eosinophils. We hypothesized that eosinophils are retained in the bronchial vasculature in the inner airway wall during bronchoconstriction because of deformation of the mucosal membrane. To test this hypothesis we induced unilateral bronchoconstriction in open chest guinea pigs by stimulating the right vagus nerve and compared the accumulation of eosinophils in the airway wall of the constricted and contralateral unconstricted lungs using histologic specimens. Results show that the density of eosinophils (number of cells/wall area) significantly increased in the inner wall and decreased in the adventitia of the constricted airways compared with the contralateral unconstricted airways. There was a positive relationship between the amount of smooth muscle shortening and the eosinophil density in the inner wall. On the other hand, this relationship was significantly negative in the adventitia. Atropine completely inhibited the eosinophil accumulation in the inner wall. These data suggest that eosinophils can accumulate in the airway inner wall during bronchoconstriction because of geometrical factors.

Drug-induced nephrotoxicity

Drug-induced renal dysfunction is not an uncommon event, which can cause significant morbidity and can be easily overlooked. Many medications can lead to renal dysfunction through various mechanisms. The most common medications or classes of medications along with their clinical presentations are discussed in this article. As can be noted, many drugs can cause nephropathy in more than one way. Because it is difficult to discuss nephrotoxicities of every reported medication, Tables 1, 2, and 3 are provided; although these tables are by no means comprehensive, they may serve as further reference. This article is intended to provide a broad overview of the spectrum of presentation associated with drug-induced nephrotoxicity to guide the clinician to familiarity with this entity.