Diagnostic procedures and long-term prognosis in bilateral renal cortical necrosis

Renal Allograft Cortical Necrosis in a COVID-19 Positive Patient

The incidence of acute kidney injury (AKI) has been reported to be higher in kidney transplant recipients infected with SARS-CoV-2 compared with the general population. Here, we report a case of cortical necrosis in the graft kidney due to COVID infection in a patient with stable graft function over the years. The patient was started on hemodialysis and treated with steroids, and anticoagulants for COVID infection. Later, he had gradual improvement in his graft function and became dialysis independent on follow up.

Partially Reversible Acute Renal Cortical Necrosis Secondary to Hyperhomocysteinemia - A Case Report and Literature Review

Acute renal cortical necrosis (ACN) is a potentially fatal renal condition. Our objective is to report a case of ACN in a young man who had developed premature atherosclerotic vascular disease and required intermittent hemodialysis support. His renal biopsy showed diffuse cortical necrosis. Subsequently, 2 weeks after the renal insult, he developed a cardioembolic stroke and was anticoagulated with low-molecular-weight heparin. Thrombophilia screen revealed elevated serum homocystein and he was treated with folate supplement and vitamin B12 injection. With these treatments, he had partial renal recovery and became dialysis independent. In conclusion, this is a rare case of ACN, which may have occurred as a complication of hyperhomocysteinemia.

Acute renal cortical necrosis in pregnancy: Clinical course and changing prognosis

Obstetric cortical renal necrosis is a serious complication that can lead to chronic renal failure and the need for chronic dialysis. The aim of renal cortical necrosis therapy is to restore hemodynamic stability, institute early dialytic therapy, and treat the underlying cause of the disease. Most cases of renal cortical necrosis do not recover a normal renal function despite intensive care. We describe the course of a patient who was diagnosed with acute renal cortical necrosis in pregnancy treated with hemodialysis for three years but then she recovered her renal function.

A Single-Centre Experience of Obstetric Acute Kidney Injury

BACKGROUND

Acute kidney injury (AKI) is a clinical syndrome characterized by a sudden decline in glomerular filtration rate leading to decreased excretion of nitrogenous waste products. It continues to be a common problem in developing countries.

AIMS

The aim of this study was to understand AKI characteristics in pregnancy and identify the factors related to its unfavorable outcome.

STUDY DESIGN

A prospective cross-sectional study.

METHODS

This prospective study was conducted between January 2013 and May 2014. In total 570 women with AKI were referred to the Kidney Institute during this period, out of which 52 patients with obstetrics AKI were included in this study.

RESULTS

Incidence of obstetric AKI was 9.12 %. Their age varied from 19 to 34 years, with an average of 26.2 years. About 42(80.8 %) patients had not received antenatal care. The main causes of AKI were obstetric hemorrhage (38.46 %) and puerperal sepsis (15.38 %). The outcome was favorable with complete renal function recovery in 55.76 % patients. Four (7.69 %) patients became dialysis dependent. Maternal mortality was 32.69 %.

CONCLUSION

Obstetric AKI is a critical situation in developing countries. Lack of antenatal care (80.8 %) is a major contributing factor for obstetric-related complications leading to renal failure. Obstetric hemorrhage (38.46 %) is the most common cause of obstetric AKI. Late referral in 18 (34.61 %), puerperal sepsis in six (33.33 %), obstetric hemorrhage in five (27.77 %) and combined sepsis and hemorrhage in five (27.77 %) are the common contributing factors leading to its unfavorable outcomes as maternal morbidity and mortality. Hence, a multidisciplinary approach is warranted to prevent such an avoidable complication.

Changing picture of renal cortical necrosis in acute kidney injury in developing country

Renal cortical necrosis (RCN) is characterized by patchy or diffuse ischemic destruction of all the elements of renal cortex resulting from significantly diminished renal arterial perfusion due to vascular spasm and microvascular injury. In addition, direct endothelial injury particularly in setting of sepsis, eclampsia, haemolytic uremic syndrome (HUS) and snake bite may lead to endovascular thrombosis with subsequent renal ischemia. Progression to end stage renal disease is a rule in diffuse cortical necrosis. It is a rare cause of acute kidney injury (AKI) in developed countries with frequency of 1.9%-2% of all patients with AKI. In contrast, RCN incidence is higher in developing countries ranging between 6%-7% of all causes of AKI. Obstetric complications (septic abortion, puerperal sepsis, abruptio placentae, postpartum haemorrhage and eclampsia) are the main (60%-70%) causes of RCN in developing countries. The remaining 30%-40% cases of RCN are caused by non-obstetrical causes, mostly due to sepsis and HUS. The incidence of RCN ranges from 10% to 30% of all cases of obstetric AKI compared with only 5% in non-gravid patients. In the developed countries, RCN accounts for 2% of all cases of AKI in adults and more than 20% of AKI during the third trimester of pregnancy. The reported incidence of RCN in obstetrical AKI varies between 18%-42.8% in different Indian studies. However, the overall incidence of RCN in pregnancy related AKI has decreased from 20%-30% to 5% in the past two decades in India. Currently RCN accounts for 3% of all causes of AKI. The incidence of RCN in obstetrical AKI was 1.44% in our recent study. HUS is most common cause of RCN in non-obstetrical group, while puerperal sepsis is leading cause of RCN in obstetric group. Because of the catastrophic sequelae of RCN, its prevention and aggressive management should always be important for the better renal outcome and prognosis of the patients.

Renal cortical necrosis is a disappearing entity in obstetric acute kidney injury in developing countries: our three decade of experience from India

RATIONAL

Obstetrical complications are the commonest causes of Renal Cortical Necrosis (RCN). However, the overall incidence of RCN in obstetric acute kidney injury in developing countries has been decreasing in recent years.

OBJECTIVE

The aim of this study was to evaluate the changing profile of RCN in obstetric AKI over the last three decades.

METHODS

This single center study included patients with biopsy proven renal cortical necrosis over a period of 32 years from 1982 to 2014. The diagnosis of RCN was suspected in patients with prolonged AKI (>4 weeks) with absolute anuria in the setting of hemorrhage, hypotension and sepsis; and was confirmed by renal biopsy. The changing pattern in the incidence, etiology and outcome of RCN in patients with obstetric AKI was compared in the three study periods, namely 1982-1991, 1992-2002 and 2003-2014.

RESULTS

Over a period of 32 years, RCN was diagnosed in 15/259(5.8%) cases of obstetric AKI. Diffuse and patchy cortical necrosis were noted in 8(53.3%) and 7(46.7%) patients, respectively. RCN occurred in 17%(11/65), 2.4%(3/125) and 1.44%(1/69) patients in 1982-1991, 1992-2002 and 2003-2014, respectively. Septic abortion was commonest cause of RCN in the first two study periods but no case was observed in last decade. The decrease in incidence of RCN over the three decades was statistically significant (p-value < 0.001). Maternal mortality decreased to zero in 2003-2014 from 72.7% in 1982-1991.

CONCLUSIONS

The incidence of RCN in obstetric AKI in developing countries has declined low enough to label it as a disappearing entity.

Maternal, fetal and renal outcomes of pregnancy-associated acute kidney injury requiring dialysis

Pregnancy-associated acute kidney injury (PAKI) is encountered frequently in developing countries. We evaluated the maternal, fetal and renal outcomes in women with PAKI who needed at least one session of dialysis. Of the total of 98 cases (mean age 28.85 ± 5.13 years; mean parity 2.65 ± 1.28) of PAKI, the most common cause of PAKI was postabortal sepsis. Eighteen patients died; those with oligoanuria, sepsis and central nervous system (CNS) involvement were at greater risk of mortality. The relative risk (RR) of neonatal mortality was lower after with full-term delivery (RR: 0.17, 95% confidence interval (CI): 0.03-0.96, P = 0.02) compared to preterm delivery. Of the 80 surviving patients, 60 (75%) patients achieved complete recovery of renal function at the end of 3 months; and of the remaining 14 had presumed (n = 4) or, biopsy-proven (n = 10) acute patchy cortical necrosis. The RR of non-recovery of renal function was high (RR: 24.7, 95% CI: 3.4- 179.5) in patients who did not recover at 6 weeks. Of the 14 patients with cortical necrosis, 3 (21.42%) became independent of dialysis at 6 months. PAKI patients should be watched for dialysis independency for 6 months.

The kidney in pregnancy: A journey of three decades

The spectrum of kidney disease occurring during pregnancy includes preeclampsia, hypertensive disorders of pregnancy, urinary tract infection, acute kidney injury, and renal cortical necrosis (RCN). Preeclampsia affects approximately 3-5% of pregnancies. We observed preeclampsia in 5.8% of pregnancies, and 2.38% of our preeclamptic women developed eclampsia. Severe preeclampsia and the eclampsia or hemolysis, elevated liver enzymes levels, and low platelets count (HELLP) syndrome accounted for about 40% of cases of acute kidney injury (AKI) in pregnancy. Preeclampsia/eclampsia was the cause of acute renal failure (ARF) in 38.3% of the cases. Preeclampsia was the most common (91.7%) cause of hypertension during pregnancy, and chronic hypertension was present in 8.3% of patients. We observed urinary tract infection (UTI) in 9% of pregnancies. Sepsis resulting from pyelonephritis can progress to endotoxic shock, disseminated intravascular coagulation, and AKI. The incidence of premature delivery and low birth weight is higher in women with UTI. The incidence of AKI in pregnancy with respect to total ARF cases has decreased over the last 30 years from 25% in 1980s to 5% in 2000s. Septic abortion-related ARF decreased from 9% to 3%. Prevention of unwanted pregnancy and avoidance of septic abortion are key to eliminate abortion-associated ARF in early pregnancy. The two most common causes of ARF in third trimester and postpartum periods were puerperal sepsis and preeclampsia/HELLP syndrome. Pregnancy-associated thrombotic thrombocytopenic purpura/hemolytic uremic syndrome and acute fatty liver of pregnancy were rare causes of ARF. Despite decreasing incidence, AKI remains a serious complication during pregnancy.

[Acute renal failure requiring haemodialysis in obstetrics]

Acute renal failure (ARF) requiring hemodialysis is a rare complication of pregnancy in western world, but in developing countries, it is still frequent. The objective of this study was to determine the epidemiology, etiologies, clinical data and outcomes for pregnant women with ARF requiring dialysis. We studied the records of 58 patients with ARF who had needed dialysis in the obstetric intensive care unit of the maternity teaching hospital of Ibn Rochd (Casablanca) between January 1st 2002 and 31st December 2008. Anterior renal diseases and post-renal causes were excluded. Epidemiological, clinical, biological data were recorded, the outcome of patients were studied 1 and 3 months after discharge from hospital. The incidence of ARF in our unit was 9.87 per 10,000 pregnancies; and constitutes 2.49% of all admissions in the obstetric ICU. The mean age and parity were respectively 28±7 years and 2.82. Main aetiology was preeclampsia-eclampsia (39 cases: 67.2%), haemorrhage (15 cases: 25.9%), sepsis (five cases: 8.6%), fetal death, (two cases: 3.6%) and acute fatty liver (one patient: 1.8%). Often, several causes were associated. In one case, we found no evident cause despite radiological imaging and histological exam. Recovery is faster in pre-eclampsia than others causes. The outcomes included renal recovery in 42 cases (72.4%), chronic renal failure in four cases (6.9%). Mortality rate was 13.8% (eight deaths). Preventive and early management of obstetrical complications could improve pregnancy-associated ARF.

Pregnancy-related acute renal failure: A single-center experience

Pregnancy-related acute renal failure (ARF) is a common occurrence and is associated with substantial maternal and fetal mortality. It also bears a high risk of bilateral renal cortical necrosis. We conducted this study to evaluate the contributing factors and to assess the frequency of cortical necrosis. In this prospective study, of the 772 patients with ARF admitted at our institute between January 2004 and May 2006, 70 had ARF associated with pregnancy complications. ARF was diagnosed by documenting oliguria (urine output <400 ml/d) or mounting azotemia in the presence of normal urine output. (serum creatinine >2 mg%). Renal biopsy was performed if a patient was found to be oliguric or required dialysis support at the end of three weeks. The incidence of pregnancy-related ARF was 9.06%. Approximately 20% cases occurred due to postabortal complications in early pregnancy and 80% following complications in late pregnancy. Puerperal sepsis was the most common etiological factor in 61.42% of the patients. Preeclampsia accounted for 28.57% of ARF. Two-thirds of patients recovered with dialysis and supportive care. The incidence of biopsy proven renal cortical necrosis was 14.8% (10 of the 70 patients). The incidence of renal cortical necrosis was 28.57% in the early pregnancy group and 10.71% in the late pregnancy group. Postabortal sepsis was the most common precipitating event for renal cortical necrosis. Maternal mortality was 18.57%. Sepsis accounted for a majority of deaths (61.53%). Pregnancy-related ARF is common in western India. Puerperal sepsis is the most frequent etiological factor. Renal cortical necrosis is common and postabortal sepsis was the most common precipitating event. Sepsis accounted for a majority of maternal mortality.

Acute renal failure due to intrinsic renal diseases: review of 1122 cases

In this study we have analyzed incidence, causes and clinical course of ARF due to primary intrarenal disease other than acute tubular necrosis. Thousand hundred and twenty two cases of ARF of diverse etiology were studied over a period of 16 years; July 1984 to Dec, 1999. Surgical ARF 231 (20.6%) were not included in the present study. Intrinsic renal diseases were responsible for ARF in 891 (79.4%) of cases. The most common intrinsic renal diseases 705 (79.4%) causing ARF were ischemic/toxic acute tubular necrosis, but not included in this study. Acute renal failure was related to acute glomerulonephritis (9.3%), acute interstitial nephritis (7%), and renal cortical necrosis in (4.6%) of cases. Therefore intrinsic renal diseases other than ATN were the causative factor for acute renal failure in 186 (20.8%) patients in our study. Crescentic (51.8%) and endocapillary proliferative glomerulonephritis (34.9%), were the main glomerular diseases responsible for ARF and 75.9% of GN was related to infectious etiology. Fifty three percent of acute interstitial nephritis was drug induced and in 25 (40%) patients it was related to an infectious etiology. Renal cortical necrosis due to HUS was observed in 16 (39%) children and majority (76.47%) of the cases had a diarrhoeal prodrome. Obstetrical complications were the main causes (61%) of cortical necrosis in adults with acute renal failure. Thus, intrinsic renal diseases other than ATN were responsible for ARF in 186 (20.8%) cases. Post-infectious glomerulonephritis, acute interstitial nephritis and renal cortical necrosis (complicating HUS in children and obstetrical complications in adult) are the main causes of acute renal failure in our study. Both acute GN and interstitial nephritis had excellent prognosis, however renal cortical necrosis was associated with a very high mortality.

Outcome of acute renal failure in meningococcemia

We studied 28 consecutive patients (18 males and 10 females), 1-32 years of age, admitted to the intensive care unit from January 1989 to July 1995, with acute renal failure (ARF) due to meningococcal septicemia. All patients were treated with dexamethasone, penicillin, and/or chloramphenicol. Twenty-two patients presented septic shock and needed fluid replacement and vasoactive drugs. Acute renal failure was oliguric in 67.8%. Maximum levels of blood urea and serum creatinine were 210.3 +/- 26.6 mg/dL and 6.9 +/- 1.3 mg/dL, respectively. Metabolic acidosis was observed in 89.3% and hyperkalemia in 43%. The fractional excretion of sodium on day 1 was high (9.9 +/- 0.6%). The urinalysis did not show trace protein, but hematuria was positive in 81%. The mortality rate was 63.3%. In the 10 survivors, oliguria was present for a period of 12.7 +/- 2.4 days, and the period to reach a normal serum creatinine level was 20.2 +/- 4.7 days, although in two female patients, 7 and 17 years old, the elevated serum creatinine persisted. Renal biopsy was performed in one of these patients which revealed bilateral cortical necrosis. These data show that acute renal failure in meningococcemia presents high mortality rate associated to shock; 80% of the survivors recover renal function; and bilateral cortical necrosis occurred in one patient in this series.

Spectrum of renal cortical necrosis in acute renal failure in eastern India

Renal cortical necrosis is an uncommon cause of acute renal failure. We report 23 cases of biopsy-proven renal cortical necrosis which constituted 6.3% (23/363) of all cases of acute renal failure studied over a period of seven years (1985-92). The patients were divided into two groups: obstetric and non-obstetric. Obstetric complications were responsible for renal cortical necrosis in 15 (65.2%) patients while non-obstetric conditions accounted for the remaining eight (34.8%) cases. The overall incidence of cortical necrosis in obstetric acute renal failure was 15/63 (23.8%) patients, the incidence being nearly equal in early (20.5%) and late (29%) pregnancy. Post-abortum renal failure was the sole cause of cortical necrosis in early pregnancy in the obstetric group. Haemolytic uraemic syndrome (three patients) and septicaemia (two patients) were the main cause of necrosis in the non-obstetric group. The cortical necrosis was diffuse and patchy in 17 and six patients, respectively. The disease had a fatal prognosis in 20 (87%) patients; mortality was due to uraemic complications and infections in the majority of patients. The high frequency of post-abortum renal cortical necrosis in our patients is similar to the experience of other Indian workers.

Acute renal failure in pregnancy

Acute renal failure (ARF) has become a very rare complication of pregnancy. This results from the virtual disappearance of septic abortion ARF and from the improvement of prenatal care, including the prevention of volume contraction which is mainly due to uterine haemorrhage, early diagnosis, and treatment of other classic maternal complications such as pre-eclampsia and acute pyelonephritis. The incidence of bilateral renal cortical necrosis has also been declining during the last decade. Acute fatty liver, a potentially fatal disease, is often complicated by ARF. Early recognition of this disorder, with prompt termination of pregnancy and intensive supportive therapy, can reduce fetal and maternal mortality rate. The syndrome of idiopathic postpartum renal failure is also associated with a high morbidity and mortality. Beyond supportive treatment, including haemodialysis or peritoneal dialysis and the use of potent antihypertensive drugs to control blood pressure and blood transfusion if necessary, specific therapy as plasma infusion, plasma exchange and antiplatelet drugs may be of value. Both peritoneal dialysis and haemodialysis may be used in gravidas with ARF. Early 'prophylactic' dialysis should be applied to pregnant women. Careful monitoring of fluid balance and anticoagulation is necessary during dialysis.

Acute renal cortical necrosis--a study of 113 patients

Over a 28-year period, 113 out of 2986 (3.8%) patients dialysed for acute renal failure at a referral center in North India were diagnosed to have acute renal cortical necrosis (ACN). Obstetric causes were responsible for ACN in 56.6% patients and nonobstetric causes in 43.4%. Within the obstetric group, ACN developed in association with complications of late pregnancy in 37.1% and following septic abortion in 19.5%. The various nonobstetric causes included viperine snake bite in 14.2%, hemolytic uremic syndrome in 11.5%, renal allograft rejection in 5.3%, acute gastroenteritis in 4.4%, acute pancreatitis in 3.5%, septicemia in 2.7%, and trauma and drug-induced IV hemolysis in 0.9% patients. Total anuria was the commonest presenting feature and was noted in 78.8% of patients. Renal histology showed diffuse cortical necrosis in 62.8% and patchy lesions in 37.2% patients. Computerized tomography (CT scan) of the kidneys revealed characteristic diagnostic findings in all the 5 patients in whom it was done. Dialytic support could be withdrawn as a result of improvement in renal function in 19 patients with patchy cortical necrosis. Dialysis-free survival of as long as 12 years has been recorded. The present study shows that, in contrast to the Western world, ACN continues to be a common cause of acute renal failure in developing countries. CT scan of the kidneys is helpful in establishing an early diagnosis.

Macroscopic hematuria as a presenting manifestation of oliguric acute tubular necrosis

Macroscopic hematuria associated with acute renal failure usually results from glomerulonephritis or structural abnormalities (stones, tumors, or infections). Acute tubular necrosis is rarely associated with macroscopic hematuria in the absence of other genitourinary abnormalities. We describe a patient who presented with macroscopic hematuria, in whom only acute tubular necrosis could be identified as a causative factor.

Acute renal failure in pregnancy

Between 1982 and 1992, 18 cases of pregnancy-related acute renal failure (PR-ARF) were observed (9% of the total number of ARF). Mean age of the women was 32 years (22-40 years). Uterine hemorrhage and preeclampsia/eclampsia were the major causes of ARF, accounting for 61% of the cases. Patchy renal cortical necrosis was suspected in 2 cases whereas signs of disseminated intravascular coagulation (DIC) or microangiopathic hemolytic anemia were present in 6 (33%) and 9 (50%) cases, respectively. Ten women required hemodialysis; and 6 of them, additional plasma exchange sessions. Five patients (28%) died during the acute phase of the illness, mainly due to brain damage, hepatic failure, and sepsis. Among the survivors, a complete (61.5%) or partial recovery (23.1%) was usually seen, but irreversible renal failure was recorded in 2 cases with postpartum hemolytic uremic syndrome (HUS). Short-lasting oligoanuria (< 3 days) represents a good prognostic index. However, the presence of vascular injury (cortical necrosis, HUS) seems to carry a poor prognosis. In conclusion, PR-ARF is still a critical occurrence, associated with serious prognosis for both women and kidneys. So far, the most effective measures remain the careful prevention and the aggressive management of the obstetric complications.

Renal effect of anti-hypertensive drugs depends on sodium diet in the excision remnant kidney model

Angiotensin converting enzyme inhibitors (ACEI) are believed to protect remnant kidney, but all previous studies used the ligation model which causes severe hypertension, and very few have compared drugs in rats having similar control of blood pressure (BP). We compared rats with uremia obtained by 70% excision of total renal mass, a model which causes mild, late hypertension. Study I compared the effects of enalapril (E), cicletanine (C) and placebo (P) in uremic (U) rats fed a 0.50% (normal-high) Na diet. Study II compared the effects of E, C, P, and guanfacine (G) in U rats fed a diet restricted to 0.25% Na (normal-low). In study I, UP rats developed progressive hypertension (140, 146, 160 and 166 mm Hg at 3, 6, 9 and 12 weeks), proteinuria (240 mg/day at 9 and 12 weeks) which were not affected by E or C. The occurrence of end-stage renal disease (ESRD) led to the sacrifice of all rats after three months. All three groups had similar severe renal lesions (over 25% sclerosed glomeruli in 5 of 10 UP, 9 of 14 UE, 7 of 14 UC rats, with huge cystic tubular dilatations). In study II, rats could be sacrificed later (6 months) and had evidence of less severe renal disease. All the drugs tested prevented hypertension throughout the study (P less than 0.001), with lowest values in UE rats. E and G, but not C, reduced proteinuria. Renal damage was reduced with E and G, but not with C, despite similar BP in C and G rats. Thus, in contrast with what was obtained in the ligation model, ACEI affected neither the BP nor the renal lesions of rats made uremic by renal excision and fed a 0.50% Na diet. Moderate Na restriction improved the consequences of nephron loss and restored the anti-hypertensive effect of drugs. However, these drugs had a different effect on renal preservation: it was dramatic with E, good with G, and undetectable with C.

Acute renal failure in hypertensive disorders of pregnancy. Pregnancy outcome and remote prognosis in thirty-one consecutive cases

The purpose of this study is to report short-term pregnancy outcome, subsequent pregnancy outcome, and remote prognosis (follow-up from 0.3 to 9.8 years) in 31 cases complicated by acute renal failure. Eighteen patients had "pure" preeclampsia and 12 patients (13 pregnancies) had chronic hypertension, parenchymal renal disease, or both before pregnancy. All patients had serial evaluation of renal function, urine microscopy, and electrolyte studies at the onset of acute renal failure and on follow-up. There were three immediate maternal deaths (two in the pure preeclampsia group and one in the other group). Nine patients (50%) in the "pure" group required dialysis during hospitalization and all 18 patients had acute tubular necrosis. Five patients (42%) in the other group required immediate dialysis and three patients had bilateral cortical necrosis. The majority of pregnancies in both groups were complicated by abruptio placentae and hemorrhage. All 16 surviving patients in the pure preeclampsia group had normal renal function on long-term follow-up (average 4.0 +/- 3.1 years). Conversely, nine of the 11 surviving patients in the second group required long-term dialysis on follow-up and four of them ultimately died of end-stage renal disease. We conclude that proper management of acute renal failure in patients with pure preeclampsia-eclampsia does not result in residual function impairment.

Pathogenesis and significance of nonprimary focal and segmental glomerulosclerosis

Injury of the glomerular microvasculature by nonimmunologic processes is often the underlying mechanism of progressive deterioration of renal function in patients with a variety of renal disorders. The structural hallmark of this injury is focal and segmental glomerulosclerosis, often accompanied by entrapment of hyalin. Although such lesions are quite characteristic for diseases that primarily affect the glomerular podocyte, similar damage occurs in association with functional and structural adaptive changes that develop as a consequence of a significant loss of functioning nephrons or other systemic disorders. Experimental studies have revealed that such functional adaptations include intrarenal vasodilatation that through increases in glomerular capillary pressure and plasma flow leads to a significant compensatory hyperfiltration. This functional state is accompanied by a parallel increase in glomerular volume, attained chiefly by expansion of matrix components and an increase in the number of endothelial and mesangial cells, but not of podocytes. The persistence of the adaptive changes results in endothelial, mesangial, and epithelial cell dysfunction revealed clinically by proteinuria and structurally by the development of microthrombosis, microaneurysms, mesangial expansion, and occlusion of capillaries by hyalin accumulation. Although all these pathologic processes can lead to segmental collapse of the capillary tuft, it is the progressive hyalin deposition in capillaries with defective or detached podocytes that represents the major mechanism in the development of segmental and eventually global glomerulosclerosis. The inability of the highly differentiated podocyte to replicate in response to systemic or locally released trophic factors ultimately results in imperfections of the capillary wall that set the stage for permeability defects amplified and accentuated by greatly augmented hydrodynamic forces. These structural and functional microvascular changes acting in concert not only facilitate the transcapillary convection of macromolecules that results in albuminuria, but can also be anticipated to play a key role in the entrapment and accumulation of larger macromolecules in front of the lamina densa in the form of hyalin material. Continuing damage to the glomerular microvasculature exacerbates the adaptive changes in surviving nephrons, closing a positive-feedback loop that culminates in end-stage renal failure.

Snake-bite-induced acute renal failure in India

Acute renal failure complicates the course in 5% to 30% of victims of severe viper poisoning. No consensus exists on the single mechanism causing acute renal failure after viper bite. It is known, however, that viper venom induces several clinical abnormalities that favor the development of acute renal failure. These alterations include a varying degree of bleeding, hypotension, circulatory collapse, intravascular hemolysis, and disseminated intravascular coagulation with or without microangiopathy. A direct cytotoxic action of snake venom on the kidney is suspected, but convincing evidence is still lacking. Severe hypocomplementemia is consistently present, but I doubt its role in the causation of renal lesions. Hypersensitivity to venomous or antivenomous protein occasionally causes acute renal failure. In sea snake poisoning, myonecrosis and myoglobinuria appear to play the predominant pathogenetic role. The renal lesions of clinical significance in envenomed patients are acute tubular and patchy or diffuse cortical necrosis. Glomerulonephritis, interstitial nephritis, and papillary necrosis have been reported in rare patients. I trust that this overview of the clinical and basic-science aspects of snake-bite-induced acute renal failure will prompt investigators to further define the pathogenetic mechanisms involved. Lessons learned may aid patients with acute renal failure of diverse causes, both here in India and around the world.

Role of coagulation in glomerular injury

A role for coagulation in renal diseases is suggested by the presence of glomerular fibrin deposits in numerous experimental and human renal diseases, some of which are of toxic origin. Fibrin may exert detrimental effects by occluding glomerular capillaries, by attracting macrophages or by direct cytotoxicity to mesangial cells. Intraglomerular fibrin deposition or formation may result in part from changes in the normal multiple haemostatic properties of glomeruli. In glomerular clotting of systemic origin, e.g., glycerol-induced acute renal failure with intravascular coagulation, inhibition by drugs of glomerular fibrinolytic activity leads to persistent thrombi and permanent renal damage. In immune glomerulonephritis, fibrin formation may depend on activation of glomerular prothrombotic properties: for example, glomerular procoagulant (tissue factor-like) activity is enhanced at the peak of mercuric chloride-induced autoimmune glomerulonephritis, characterized by massive fibrin deposits. Finally, fibrin deposits probably contribute to the progressive renal lesions and chronic renal failure seen in rats with kidney damage, in which anticoagulant therapy has a beneficial effect.

Acute renal failure in pregnancy

Acute renal failure has become a very rare complication of pregnancy. This results from the virtual disappearance of septic abortion ARF and from the improvement of prenatal care, including the prevention of volume contraction which is mainly due to uterine haemorrhage, early diagnosis, and treatment of other classic maternal complications such as pre-eclampsia and acute pyelonephritis. The incidence of BRCN has also been declining during the last decade. Acute fatty liver, a potentially fatal disease, is often complicated by ARF. Early recognition of this disorder with prompt termination of pregnancy and intensive supportive therapy can reduce fetal and maternal mortality rate. The syndrome of idiopathic postpartum renal failure is also associated with a high morbidity and mortality. Beyond supportive treatment including haemo- or peritoneal dialysis, the use of potent antihypertensive drugs to control blood pressure and blood transfusion if necessary, specific therapy as plasma infusion, plasma exchange and antiplatelet drugs may be of value. Both peritoneal dialysis and haemodialysis may be used in gravidas with ARF. Early 'prophylactic' dialysis should be applied to pregnant women. Careful monitoring of fluid balance and anticoagulation is necessary during dialysis.

Acute renal failure in pregnancy: 1987

Acute renal failure has become a rare complication of pregnancy due to the virtual disappearance of septic abortion and to better prenatal care, including prevention of blood volume contraction. The incidence of bilateral renal cortical necrosis also decreased in recent years. Severe preeclampsia-eclampsia may be accompanied by acute tubular necrosis. Acute fatty liver of pregnancy is often associated with renal failure. It is a medical emergency. The diagnosis should be made promptly, before liver failure becomes too severe. This should be followed by immediate delivery. In postpartum hemolytic uremic syndrome, plasma infusion, plasma exchange, and/or antiplatelet drug therapy may be of value.

Captopril slows the progression of chronic renal disease in partially nephrectomized rats

The effect of captopril, an angiotensin-converting enzyme inhibitor, on the progression of chronic renal disease was studied in rats subjected to partial nephrectomy. Following ablation of approximately 70% of their renal mass, rats were divided into three treatment groups: group I received a placebo treatment; group II received daily po administrations of captopril; group III received captopril at the same dosage schedule as group II, but the drug was not given for 4 weeks in the middle of the treatment period. Measurements of renal function were performed at 4-week intervals, and light microscopic evaluation of the remnant kidneys was performed following 19 weeks of treatment. Deterioration of renal function, as measured by endogenous creatinine clearance, plasma creatinine, and plasma urea nitrogen, progressed more rapidly in group I than the other two groups. Twenty-four-hour urinary protein excretion was higher in group I than the others, except in group III following the 4-week period when captopril was not administered. Morphologic damage in the remnant kidney was significantly greater in group I than group II (p = 0.007). The renal lesions in the rats of group III were intermediate in severity. Histopathologic ranking of the remnant kidneys was correlated with antemortem laboratory parameters (r greater than or equal to 0.50; p less than 0.05). In a second experiment, similarly nephrectomized rats receiving po captopril daily had significantly longer survival, at 260 days, postnephrectomy than rats receiving a placebo (p = 0.0045). We conclude that captopril retards the progression of renal damage and increases survival time in this model of chronic renal disease. The mechanism may involve the alteration of potentially harmful intraglomerular hemodynamic changes which occur in the remnant kidney model.

The role of dietary protein in the progression and symptomatology of chronic renal failure

Dietary factors may have substantial impact on the clinical manifestations and even the progression of chronic renal failure. Proper dietary management can prevent certain uremic complications, decrease azotemia, and may even prevent the loss of residual renal function. Recent studies indicate that dietary protein may accelerate the normal age-related deterioration of renal function in rats. The extensive ablation of functional renal mass in rats leads to hyperemia and hyperfiltration in remnant nephrons. Continued hyperfiltration theoretically results in glomerular damage, proteinuria, and ultimately glomerular sclerosis. Dietary protein restriction reduces the remnant nephron hyperfiltration and reduces the rate of glomerular sclerosis, at least in the rat. The role of dietary protein in the pathogenesis of human nephrosclerosis remains controversial. Though dietary factors may or may not affect the rate of progression of renal insufficiency, there is no doubt that proper dietary management can limit or forestall uremic symptoms and the need for dialysis. Diets containing about 0.5 gm protein/kg body weight/day usually maintain a neutral or slightly positive nitrogen balance, while lesser amounts usually result in malnutrition. When protein intake exceeds 0.5 gm/kg/day azotemia increases dramatically. The use of nitrogen-free keto- or hydroxy-analogues of amino acids promotes positive nitrogen balance while reducing azotemia in patients with near-end-stage renal disease.

Renal cortical necrosis and Purtscher's retinopathy in hemorrhagic pancreatitis

A patient presented with acute hemorrhagic pancreatitis complicated by both renal cortical necrosis and Purtscher's retinopathy. Either of these two complications is rare and never before have both been reported in the same patient. The patient's renal insufficiency required hemodialysis; it gradually improved over two years when dialysis could be discontinued. The patient's retinopathy included bilateral hemorrhages and cotton wool spots; visual fields and acuity remained normal. Funduscopic lesions disappeared by three months after the acute event. These two rare vasculo-occlusive complications of pancreatitis simultaneously occurring in one individual might suggest complement-mediated leukostatic mechanisms.

The hyperfiltering glomerulus

The observation has been made that after any of a variety of initial renal injuries, nephron units that have been spared undergo structural and functional compensations. The functional compensation of increased perfusion of residual nephrons may present deleterious, maladaptive stresses to those surviving nephrons and lead to their ultimate destruction. This hypothesis provides a final common pathway for the progression of many different renal diseases to renal failure and explains the tendency of renal insufficiency to progress rather than stabilize.

Further studies of the response of kidney lysosomes to aminoglycosides and other cations

Rat renal cortical lysosomes were isolated in 0.3 M sucrose containing 1 mM EDTA by differential centrifugation. Lysosomes were incubated in isotonic sucrose or isotonic glycine with various concentrations of endogenous and exogenous compounds at 37 degrees for 1 hr. Lysosomes were resedimented, and the N-acetyl-beta-glucosaminidase (NAG) activity was measured in the supernatant fraction and the disrupted pellet and the percentage of total NAG released was calculated. Gentamicin and its C1 and C2 components had similar potencies for inhibiting NAG release from lysosomes at low concentrations. The release of alpha-galactosidase and beta-galactosidase from lysosomes was also inhibited by streptomycin and gentamicin. Mepacrine at low concentrations stabilized lysosomes and at high concentrations disrupted lysosomes. This drug also enhanced the effect of low concentrations of gentamicin on lysosomes. Inositol hexaphosphoric acid was a potent antagonist of the effect of low concentrations of gentamicin and mepacrine on lysosomes. Rats were treated with gentamicin at doses of 40, 80 and 160 mg/kg for 1 and 3 days. NAG excretion in gentamicin-treated groups as compared to saline controls was unchanged at day 1. Only the 160 mg/kg treatment group showed a tendency toward elevated renal cortical NAG at day 1 (P less than 0.06). All treatment groups had elevated renal cortical NAG at day 3, while the 160 mg/kg group also had elevated NAG excretion. Lysine, arginine, L-canavanine and polymyxin B all affected NAG release from lysosomes in vitro. Lysine enhanced the disruptive effect of high gentamicin concentrations on lysosomes. Ferric and ferrous ions, tested over widely varied concentrations, inhibited NAG release at low concentrations while enhancing NAG release at high concentrations. We therefore conclude that the nephrotoxicity of aminoglycoside and other endogenous and exogenous renally excreted cationic compounds may be produced by their effects on lysosomes in the proximal renal tubule.

Spectrum of acute cortical necrosis in Indian patients

Forty-nine out of 662 patients (7.4%) dialysed for acute renal failure were found to have bilateral renal cortical necrosis. Amongst 6061 autopsies carried out in our centre during the same period, the incidence of cortical necrosis was 0.7%. Obstetric causes were responsible for the renal lesion in 35 (71%) and non-obstetrical causes in 14 patients. In the obstetric group, cortical necrosis was observed in association with spontaneous or induced abortion in 39% and as a complication of late pregnancy in 33%. The non-obstetric causes included snake bite in 26 (12%), acute gastro-enteritis in 5 (10%), haemolytic uremic syndrome in 2 (4%) and G6PD deficiency with intravascular haemolysis in one patient (2%). Thirty-nine (80%) patients were anuric or severely oliguric throughout their illness but a steady rise in urinary output following a protracted phase of oligo-anuria was observed in ten patients. Forty-two (86%) patients died and seven survived. None of the survivors, however, achieved a normal renal function (Ccr 8 ml to 28 ml/min). The diagnosis of renal lesion was confirmed during life in 8 and after death in 41 patients. Morphological lesions were consistent with bilateral diffuse cortical necrosis in 39 (80%) and patchy lesions in 10 patients. Factors responsible for the high incidence of cortical necrosis amongst Indian patients have been high-lighted.

Nuclear medicine in acute and chronic renal failure

The diagnostic value of renal scintiscans in patients with acute or chronic renal failure has not been emphasized other than for the estimation of renal size. 131I OIH, 67gallium, 99mTcDTPA, glucoheptonate and DMSA all may be valuable in a variety of specific settings. Acute renal failure due to acute tubular necrosis, hepatorenal syndrome, acute interstitial nephritis, cortical necrosis, renal artery embolism, or acute pyelonephritis may be recognized. Data useful in the diagnosis and management of the patient with obstructive or reflux nephropathy may be obtained. Radionuclide studies in patients with chronic renal failure may help make apparent such causes as renal artery stenosis, chronic pyelonephritis or lymphomatous kidney infiltration. Future correlation of scanning results with renal pathology promises to further expand nuclear medicine's utility in the noninvasive diagnosis of renal disease.