Plasma renin activity in acute poststreptococcal glomerulonephritis and the haemolytic-uraemic syndrome

Angiotensin II and post-streptococcal glomerulonephritis

BACKGROUND

Post-streptococcal glomerulonephritis (PSGN) is a consequence of the infection by group A beta-hemolytic streptococcus. During this infection, various immunological processes generated by streptococcal antigens are triggered, such as the induction of antibodies and immune complexes. This activation of the immune system involves both innate and acquired immunity. The immunological events that occur at the renal level lead to kidney damage with chronic renal failure as well as resolution of the pathological process (in most cases). Angiotensin II (Ang II) is a molecule with vasopressor and pro-inflammatory capacities, being an important factor in various inflammatory processes. During PSGN some events are defined that make Ang II conceivable as a molecule involved in the inflammatory processes during the disease.

CONCLUSION

This review is focused on defining which reported events would be related to the presence of this hormone in PSGN.

Gastroenteritis in an adult female revealing hemolytic uremic syndrome: Case report

Nowadays acute gastroenteritis infection caused by Escherichia coli (E. coli) O157:H7 is frequently associated with hemolytic uremic syndrome (HUS), which usually developed after prodromal diarrhea that is often bloody. The abdominal pain accompanied by failure kidney is a suspicious symptom to develop this disorder. Their pathological characteristic is vascular damage which manifested as arteriolar and capillary thrombosis with abnormalities in the endothelium and vessel walls. The major etiological agent of HUS is enterohemorragic (E coli) strain belonging to serotype O157:H7. The lack of papers about HUS associated to gastroenteritis lead us to report this case for explain the symptoms that are uncommon. Furthermore, this report provides some strategies to suspect and make an early diagnosis, besides treatment approach to improving outcomes and prognosis for patients with this disorder.

Targeting renin-angiotensin system in malignant hypertension in atypical hemolytic uremic syndrome

Hypertension is common in hemolytic uremic syndrome (HUS) and often difficult to control. Local renin-angiotensin activation is believed to be an important part of thrombotic microangiopathy, leading to a vicious cycle of progressive renal injury and intractable hypertension. This has been demonstrated in vitro via enhanced tissue factor expression on glomerular endothelial cells which is enhanced by angiotensin II. We report two pediatric cases of atypical HUS with severe refractory malignant hypertension, in which we targeted the renin-angiotensin system by using intravenous (IV) enalaprilat, oral aliskiren, and oral enalapril with quick and dramatic response of blood pressure. Both drugs, aliskiren and IV enalaprilat, were effective in controlling hypertension refractory to multiple antihypertensive medications. These appear to be promising alternatives in the treatment of severe atypical HUS-induced hypertension and hypertensive emergency.

Paediatric nephrology: the last 50 years

In 1965, the specialty of paediatric nephrology was in its infancy. Following the development of a landmark collaborative research study, the International Study of Kidney Disease in Childhood in the mid-1960s, the first specialist societies were formed: the European Society of Pediatric Nephrology in 1967 and the American Society of Pediatric Nephrology in 1969. The extraordinary improvements in care delivered to children with kidney disease over the past 50 years are too broad to cover in any one paper. They traverse the spectrum of diagnosis, classification, therapeutics, social well-being and transition to adult care. We have selected four case scenarios to highlight these changes in key areas of paediatric nephrology: post-streptococcal glomerulonephritis, nephrotic syndrome, haemolytic uraemic syndrome and neonatal dialysis and childhood transplantation.

Post-streptococcal acute glomerulonephritis in children: clinical features and pathogenesis

Post-streptococcal acute glomerulonephritis (PSAGN) is one of the most important and intriguing conditions in the discipline of pediatric nephrology. Although the eventual outcome is excellent in most cases, PSAGN remains an important cause of acute renal failure and hospitalization for children in both developed and underdeveloped areas. The purpose of this review is to describe both the typical and less common clinical features of PSAGN, to outline the changes in the epidemiology of PSAGN over the past 50 years, and to explore studies on the pathogenesis of the condition with an emphasis on the search for the elusive nephritogenic antigen.

Plasma renin activity in haemolytic uraemic syndrome

Plasma renin activity (PRA) was measured in 50 consecutive patients (aged 4 months to 12 years) admitted during the acute phase of the haemolytic uraemic syndrome (HUS). Blood samples were taken as soon as the diagnosis was made and prior to any diuretic, anti-hypertensive or dialysis treatment. Prodromal diarrhoea was present in all but 3 patients, 17 were anuric and 12 were oliguric. PRA ranged from 0.3 to 24.2 ng/ml per hour and was low compared with values in normal infants and children: in 13 HUS patients PRA was above the median and in 37 it was below the median. PRA was significantly, independently and inversely related to age. There was no correlation, however, with blood pressure, urine output, volume status and serum levels of sodium, potassium and creatinine. Moreover, no relationship was found between PRA and the course of the disease. Our findings do not support the idea that renin activation plays a role in the pathophysiology of the haemolytic uraemic syndrome.

Hemolytic-uremic syndrome

HUS is one of the most common causes of acute renal failure in childhood. D+ HUS is the most common form and usually follows an episode of hemorrhagic colitis due to VTEC or S. dysenteriae type 1. The SLT elaborated by these organisms is responsible for the endothelial damage that is the initial insult in the pathogenesis of the acute renal failure. Excellent supportive care is necessary to reduce the mortality and morbidity due to HUS.

Evaluation of captopril versus reserpine and frusemide in treating hypertensive children with acute post-streptococcal glomerulonephritis

We have evaluated the effect of oral captopril versus a combination of oral reserpine and frusemide in the treatment of 20 children with post-streptococcal glomerulonephritis (APGN) with hypertension. Captopril produced a significantly greater reduction in systolic and diastolic blood pressure in both the standing and supine positions than reserpine + frusemide at 0.75, 1, 1.25, 8, 24, 48 and 72 h after initiating treatment. Neither postural hypotension nor reflex tachycardia accompanied the therapeutic effect of captopril. Blood urea, serum creatinine and creatinine clearance did not change significantly after therapy in either study group. Three days after initiating treatment, the 24 h urinary catecholamine output increased significantly in children who received captopril but did not change in children treated with frusemide and reserpine.

Hyperkalemia in acute glomerulonephritis due to transient hyporeninemic hypoaldosteronism

Transient hyperkalemia has been reported to occur in patients with acute glomerulonephritis, but the pathogenetic mechanism has not been investigated systematically. We studied the mechanism of hyperkalemia (5.7 to 6.7 mmol/liter) in four men with post-infectious glomerulonephritis. All four patients had clinical findings consistent with acute glomerulonephritis (edema, hypertension, proteinuria, hematuria, and an elevated ASO titer) and a renal biopsy performed in three of the patients confirmed the diagnosis. In comparison to normal subjects (N = 18), plasma aldosterone (5.4 +/- 1.6 vs. 22.8 +/- 2.6 ng/dl, P less than 0.005) and plasma renin activity (0.3 +/- 0.2 vs. 4.3 +/- 0.6 ng/ml/hr, P less than 0.005) were reduced. Hyperkalemia resolved within one to two weeks in two patients as the nephritis resolved and diuresis ensued, and aldosterone and renin levels obtained at follow-up visits were normal. Hyperkalemia persisted despite furosemide-induced diuresis in the other two patients, but resolved with fludrocortisone treatment. Thus, hyperkalemia in patients with acute glomerulonephritis is a manifestation, in part, of hyporeninemic hypoaldosteronism. It is ameliorated by mineralocorticoid therapy and improves spontaneously with resolution of the glomerulonephritis.

Atrial natriuretic factor in the acute nephritic and nephrotic syndromes

Because the role of systemic hormones in the pathophysiology of edema in acute renal disease remains incompletely understood, we compared the levels of atrial natriuretic factor (ANF) and plasma renin activity (PRA) in patients with acute glomerulonephritis (AGN), nephrotic syndrome (NS), and normal individuals during salt deprivation and salt loading. Sixteen patients with AGN (10 males) and nine patients with NS and hypoalbuminemia (7 males) were studied on admission, and after recovery (12 AGN patients) or remission (4 NS patients). Eighteen normal controls were each studied after five days on a low (20 mEq Na/day), regular (120 mEq Na/day) and high (300 mEq Na/day) dietary salt intake. Patients with AGN and NS had comparable edema (AGN 2.8 +/- 0.53 kg; NS 3.36 +/- 0.47 kg; SE) and urinary Na excretion (mean +/- SEM: AGN 0.97 +/- 0.11 mEq/hr; NS 1.06 +/- 0.16 mEq/hr), but AGN patients had five times higher ANF (AGN 27.2 +/- 4.06 fmol/ml; NS 5.51 +/- 1.02 fmol/ml; P less than 0.001) and six times lower PRA ng/liter.sec levels (AGN 0.187 +/- 0.047; NS 1.144 +/- 0.222; P less than 0.001) than NS patients. The degree of edema was correlated with ANF levels in AGN patients (P less than 0.001) but not in NS patients. There was a strong exponential negative correlation (r = -0.773, P less than 0.0001) between ANF and PRA, in which AGN patients and Na-restricted controls were located in the opposite ends of the volume sensing-response, and NS patients in the middle, alongside controls with regular Na intake.(ABSTRACT TRUNCATED AT 250 WORDS)

Intravenous diazoxide in acute poststreptococcal glomerulonephritis

Twenty-six patients with hypertension secondary to acute poststreptococcal glomerulonephritis were treated by the rapid intravenous infusion of diazoxide. The average pretreatment systolic pressure was 159 mm Hg. Five minutes after administration, the average systolic pressure was 122 mm Hg (a 23% reduction). The average initial diastolic pressure was 104 mm Hg, which fell 5 minutes after diazoxide injection to 71 mm Hg (a 32% reduction). No hypotensive episodes were noted. Occasional episodes of nausea occurred. Concentrations of blood glucose increased after administration of diazoxide; however, no values were above 155 mg/dl. Diazoxide appears to be a safe antihypertensive drug that is effective in the treatment of hypertension secondary to acute poststreptococcal glomerulonephritis.