Acute acetaminophen nephrotoxicity and urinary gamma-glutamyl transferase activity in rats

Evaluation of colistin nephrotoxicity administered at different doses in the rat model

OBJECTIVE

This study evaluated the usefulness of plasma Cystatin C (pCysC) along with urinary neutrophil gelatinase-associated lipocalin (NGAL), γ-glutamyltransferase (GGT), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), aspartate (AST) and alanine (ALT) aminotransferase to monitor colistin nephrotoxicity.

METHOD

Male rats were given intramuscular (i.m.) injections of colistin in doses of 150,000 (G1), 300,000 (G2) and 450,000 IU/kg/day (G3) or normal saline (Control), every 12 h for 7 days. After the 14th injection, animals were placed in metabolic cages and urine samples were collected in the next 12 h. Thereafter, animals were euthanized, blood samples were collected and kidneys were removed for histological assessment.

RESULTS

Nephrotoxicity was completely dose-dependent according to pathologic findings. The major insults were acute tubular necrosis in the tubules of G3. No significant change in pCr was observed in all treated groups, but pCysC increased in the G3 compared to the control. In urinary markers, uNGAL level showed a dose dependant increase with significant change in the G2 and G3 groups compared to the control. However, there was no significant change in the AST, ALT, LDH or ALP activities but only GGT increased in the G3 compared to the control.

CONCLUSION

Based on colistin doses used in our experimental study on rat model, histopathologic assessment remains the most accurate way to diagnose colistin nephrotoxicity. pCysC appears to be more reliable than pCr, and uNGAL seems to be the most sensitive factor of colistin nephrotoxicity.

Earlier recognition of nephrotoxicity using novel biomarkers of acute kidney injury

CONTEXT

A broad range of drugs and chemicals are capable of evoking acute kidney injury, which is conventionally determined by rising serum creatinine concentrations. However there are important limitations to this approach, and there has been interest in alternative biomarkers that might provide a more sensitive and rapid means of detecting acute kidney injury. Most of the available clinical data have thus far been ascertained in patients requiring critical care or with acute sepsis. However, if a sensitive indicator of acute kidney injury were developed, then this could provide a significantly improved means of detecting the effects of acute drug or toxin exposure.

OBJECTIVE

To review the available data concerning potential biomarkers of acute kidney injury and to assess their relative strengths and weaknesses in comparison to existing methods based on serum creatinine concentrations. A large number of possible biomarkers have been proposed. Evidence for individual biomarkers is reviewed with a particular emphasis on those with potential application in clinical toxicology. Where available, comparative data are presented.

METHODS

There were 236 papers identified using Medline, Embase, and Google Scholar databases, of which 52 were considered directly relevant. CREATININE: Creatinine is subject to glomerular filtration and, to a lesser extent tubular secretion. Serum concentrations are an insensitive marker of acute kidney injury, and the speed of an increase from baseline depends on the magnitude of the acute injury and pre-existing kidney functional reserve. A wide range of inter-individual concentrations means that single time-point determinations are difficult to interpret, and acute kidney injury may not manifest as a detectable increase in serum creatinine concentrations until at least 24-48 h after the primary insult. KIDNEY ENZYMES: Enzymes are often localised to specific anatomical locations, and acute injury may cause a detectable increase in urinary activity due to up-regulated activity or leakage due to cell membrane disruption. Key examples include gamma-glutamyl transpeptidase (GGT), glutathione-S-transferase (GST), and N-acetyl-glucosaminidase (NAG), which are found predominantly in the proximal tubule and urinary enzyme activity increases after acute exposure to heavy metals and other nephrotoxins. NEUTROPHIL GELATINASE-ASSOCIATED LIPOCALIN: Neutrophil gelatinase-associated lipocalin (NGAL) is expressed by renal tubular epithelium, and a rise in urinary concentrations may provide an indicator of acute renal injury caused by any one of a broad range of provoking factors that is detectable before a rise in serum creatinine concentrations. CYSTATIN C: Serum and urinary cystatin C concentrations are closely related to kidney function and, for example, in acute tubular necrosis allow better prediction of the need for renal replacement therapy than serum creatinine concentrations. KIDNEY INJURY MOLECULE 1: Kidney injury molecule 1 (KIM-1) is expressed in the proximal tubule in the setting of acute ischaemia. For example, urinary KIM-1 concentrations becomes detectable within 24 h of acute tubular necrosis. Urinary KIM-1 expression may be detected after exposure to a variety of nephrotoxic agents, even when serum creatinine concentrations do not increase, and this has been accepted by regulatory authorities as a sensitive biomarker of acute kidney injury during early drug development.

CONCLUSIONS

Novel biomarkers appear capable of offering a more sensitive means of detecting acute kidney injury than existing approaches. Certain of these allow discrimination between the various mechanisms and anatomical site of acute injury. Ultimately, clinical assessment might incorporate a panel of different biomarkers, each informing on the integrated aspects of glomerular, tubular and interstitial function. Presence of biomarkers may in some cases detect mild or transient renal dysfunction that is presently undetected, and the clinical relevance needs further exploration. Whilst many potentially useful biomarkers have been proposed, comparatively few clinical data exist to support their validity in routine practice. Further prospective clinical studies are required to examine the validity of biomarkers after acute drug or toxin exposure, and to establish whether they might offer improved clinical outcomes in the setting of clinical toxicology.

Delayed onset of acute renal failure after significant paracetamol overdose: A case series

Acute renal failure is a recognized manifestation of paracetamol toxicity, but comparatively little data is available concerning its onset and duration. The present study sought to characterize the time course of rising serum creatinine concentrations in paracetamol nephrotoxicity. Renal failure was defined by serum creatinine concentration ≥150 μmol/L (1.69 mg/dL) or ≥50% increase from baseline. Serum creatinine concentrations and alanine aminotransferase activity were considered with respect to the interval after paracetamol ingestion. There were 2068 patients with paracetamol overdose between March 2005 and October 2007, and paracetamol nephrotoxicity occurred in 8 (0.4%). All had significant hepatotoxicity, and peak serum alanine aminotransferase activity occurred at 2.5 days (2.2 to 2.9 days) after ingestion. Peak serum creatinine concentrations did not occur until 5.5 days (4.4 to 5.9 days) after ingestion (p = .031 by Wilcoxon test). Serum creatinine concentrations slowly restored to normal, and renal replacement was not required. In this patient series, rising serum creatinine concentrations only became detectable after more than 48 hours after paracetamol ingestion. Therefore, renal failure might easily be missed if patients are discharged home before this. Further work is required to establish the prevalence of paracetamol-induced nephrotoxicity, and its clinical significance.

Proteinuria is unrelated to the extent of acute acetaminophen overdose: a prospective clinical study

BACKGROUND

Acute renal failure is a recognized complication of acute acetaminophen overdose. Its detection depends on rising creatinine concentrations, which is an insensitive method. The present study examined whether proteinuria might correspond with the extent of acute acetaminophen exposure as a possible early marker of renal effects.

METHODS

A prospective case-control study included patients attending the emergency department within 24 hours of acetaminophen ingestion. A urine specimen was collected within 12 hours of hospital attendance for creatinine, albumin, and protein determination. Equivalent 4-hour acetaminophen concentrations were used to indicate drug exposure: mild if >100 g/L (>662 mmol/L), moderate if 100-200 g/L (662-1323 mmol/L), or severe if <200 g/L (<1323 mmol/L). Data are presented as median (interquartile range) and groups compared using Mann Whitney and chi-square tests.

RESULTS

Seventy patients were studied (17 men, 53 women), age 37 years (23-45 years). The stated acetaminophen dose was 15 g (8-20 g), and interval between ingestion and presentation was 4.6 hours (4.1-7.9 hours). Urinary albumin concentrations were 8 mg/L (0-12 mg/L) in the mild group, 12 mg/L (5-25 mg/L) in the moderate group, and 11 mg/L (6-22 mg/L) in the severe group. Total protein concentrations were 90 mg/L (50-183 mg/L), 70 mg/L (40 to 130 mg/L), and 110 mg/L (75-205 mg/L), respectively. The proportions of patients who had urine albumin:creatinine ratio >3 mg/mmol were 20.8%, 23.5%, and 21.2%, respectively. None of the patients developed acute renal failure.

CONCLUSIONS

No relationship was found between the extent of acute acetaminophen exposure and proteinuria. Further work is required to examine whether urinary protein excretion is altered in patients who subsequently develop acute renal failure following acetaminophen overdose.

Experimental study on effects of deferoxamine mesilate in ameliorating cisplatin-induced nephrotoxicity

PURPOSE

Cisplatin (CCDP), an indispensable agent of several chemotherapy protocols, has serious dose limiting side effects, including nephrotoxicity. In this experimental study, we used deferoxamine mesilate (DFO), an iron chelating agent, to ameliorate cisplatin-induced nephrotoxicity.

MATERIALS AND METHODS

Sixty adult male bulb-c mice were divided in 6 equal groups. Group 1 received distilled water, group 2 received 100 mg/kg DFO, group 3 received 0.9 mg/kg CCDP, group 4 received 100 mg/kg DFO one hour before 0.9 mg/kg CCDP, group 5 received 1.8 mg/kg CCDP, and group 6 received 200 mg/kg DFO one hour before 1.8 mg/kg CCDP transperitoneally for 10 days. The next day, blood and urine samples were obtained, and all the animals were sacrificed, the kidneys and testes were removed, and histopathologic and biochemical analyses were performed.

RESULTS

Low-dose and high-dose CCDP treated mice had significantly more extensive proximal tubular degeneration (p < 0.001) when compared to control animals. Moreover, these changes were significantly less extensive in the mice taking DFO than mice taking CCDP. DFO showed no effect on cisplatin induced testicular histopathology. The cisplatin administration significantly increased the serum urea and plasma creatinin concentrations, and DFO administration prior to CCDP significantly decreased serum urea and plasma creatinin concentrations.

CONCLUSION

Our findings suggest that DFO administration may be safe and useful for ameliorating cisplatin-induced nephrotoxicity.