[Acute kidney failure]

[Acute renal failure]

The acute renal failure is characterized by a rapid deterioration of the renal function. In addition to the usual prerenal, intrinsic and postrenal causes of an acute renal failure distinct causes have to be considered for oncological patients. Factors imminent to the malignant disease, e. g. paraneoplastic syndromes or retroperitoneal bulks can account for an acute renal failure. Paraproteins as produced by a multiple myeloma are other possible causes for renal dysfunction. For some anticancer drugs nephrotoxicity is a potential side effect, in particular for cisplatin, methotrexate, ifosfamide and melphalan. A hemolytic uremic syndrome may be induced by mitomycin and gemcitabine. Extensive surgery can be associated with rhabdomyolysis and myoglobinuria and results in renal impairment. Treatment of a chemosensitive neoplasia with a highly effective regimen may result in a tumor lysis syndrome with hyperuricemia, hyperkalemia, hyperphosphatemia and hypocalcemia.

Renal dysfunction in falciparum--malaria is detected more often when assessed by serum concentration of cystatin C instead of creatinine

OBJECTIVES

To estimate the frequency of renal dysfunction in falciparum malaria by serum concentration of cystatin C, a new sensitive indicator of the glomerular filtration rate (GFR).

METHODS

Retrospective study of stored sera and patient files. Assessment of renal function by serum concentration of creatinine and cystatin C and comparison of the results from both indicators of GFR.

RESULTS

A total of 108 adult patients with falciparum malaria were included in the study. Concentration of creatinine and cystatin C correlated well (r = 0.706; P < 0.001). Elevated cystatin C was more frequent than elevated creatinine (54.6%vs. 20.4%; P < 0.001). Patients older than 50 years developed renal dysfunction more often (P < 0.05) than younger ones. Results from cystatin C and creatinine were concordant in 63 (58.3%) and contradictory in 45 (41.6%) cases. Four (3.7%) patients had elevated creatinine but normal cystatin C levels, hence 63 patients (58.3%) showed elevation of at least one indicator of GFR. The frequency of elevated cystatin C and elevated creatinine was unrelated to body weight, gender or bilirubin level.

CONCLUSIONS

The prevalence of impaired renal function in patients with falciparum malaria seems to have been underestimated in the past. Using a sensitive marker, 55% of the patients have a reduced GFR.

Postischemic acute renal failure is reduced by short-term statin treatment in a rat model

Postischemic acute renal failure (ARF) is common and often fatal. Cellular mechanisms include cell adhesion, cell infiltration and generation of oxygen free radicals, and inflammatory cytokine production. Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors ("statins") directly influence inflammatory mechanisms. The hypothesis that ischemia-induced ARF could be ameliorated with statin treatment was investigated and possible molecular mechanisms were analyzed in a uninephrectomized rat model. Male Sprague-Dawley rats were pretreated with cerivastatin (0.5 mg/kg) or vehicle for 3 d. Ischemic ARF was induced by left renal artery clipping for 45 min, while the right kidney was being removed. After 24 h of ARF, serum creatinine levels were increased 7.5-fold in vehicle-treated control animals with ARF, compared with sham-operated animals (P < 0.005). Statin treatment reduced the creatinine level elevation by 40% (P < 0.005). Simultaneously, ischemia-induced severe decreases in GFR were significantly ameliorated by statin treatment (sham operation, 0.95 +/- 0.09 ml/min, n = 13; ischemia without treatment, 0.06 +/- 0.02 ml/min, n = 9; ischemia with statin pretreatment, 0.21 +/- 0.03 ml/min, n = 11; P < 0.001). Furthermore, statin pretreatment prevented the occurrence of tubular necrosis, with marked loss of the brush border, tubular epithelial cell detachment, and tubular obstruction in the S3 segment of the outer medullary stripe. In addition, monocyte and macrophage infiltration was almost completely prevented, intercellular adhesion molecule-1 upregulation was greatly decreased, and inducible nitric oxide synthase expression was reduced. Fibronectin and collagen IV expression was reduced, approaching levels observed in sham-operated animals. In vehicle-treated rats with ARF, mitogen-activated protein kinase extracellular activated kinase-1/2 activity was increased and the transcription factors nuclear factor-kappaB and activator protein-1 were activated. Statin treatment reduced this activation toward levels observed in sham-operated rats. The data suggest that hydroxy-3-methylglutaryl coenzyme A reductase inhibition protects renal tissue from the effects of ischemia-reperfusion injury and thus reduces the severity of ARF. The chain of events may involve anti-inflammatory effects, with inhibition of mitogen-activated protein kinase activation and the redox-sensitive transcription factors nuclear factor-kappaB and activator protein-1.