Arterial hypertension and cystatin C during neonatal physiologic dehydration.

A reduced nephron number may play a role in the pathogenesis of arterial hypertension (AH), and it is well recognized that individual nephron endowment is widely variable. However, nephrons count is technically impossible in vivo. Based on the observation that subjects with a reduced nephron mass exhibit an increase in renal functional biomarkers during acute dehydration, we hypothesized that cystatin C concentration during neonatal physiological dehydration could identify subjects with reduced nephron endowment. This is a prospective, observational, cohort study enrolling healthy, caucasian, term neonates born after an uneventful pregnancy. Two groups of newborns were compared: neonates born to fathers on antihypertensive treatment (HF) versus those born to proven normotensive fathers older than 40 years of age (NF). Enrolled newborns underwent cystatin C determination at the time of newborn screening. Forty newborns with HF and 80 with NF were enrolled. No differences in baseline characteristics were observed between the two groups except for the number of hypertensive grandparents higher among newborns to HF (47.8% vs. 21.1%; p: 0.001). Cystatin C was significantly higher in newborns with HF (1.62 ± 0.30 mg/L vs 1.41 ± 0.27 mg/L; p < 0.001). Linear regression analysis corrected for confounders confirmed that paternal hypertension was the only variable significantly associated with high cystatin C level during post-natal dehydration. Besides offering new insights on the pathogenesis of familial hypertension, our results support the specific role of nephron endowment and suggest the possibility of identifying subjects at risk for reduced nephron endowment as early as at birth.

Fluid intake and blood pressure in children: the Salus per Aquam project.

BACKGROUND: Sodium intake is known to contribute to the development of hypertension, thus intake reduction is a cornerstone in the prevention and management of hypertension. The increase in renal sodium excretion might represent a further potential preventive and/or therapeutic opportunity. OBJECTIVE: To explore the working hypothesis that an increased fluid intake can improve renal sodium handling towards a decrease in blood pressure. METHODS: The SPA Project is a multicenter, observational, cross-sectional, cohort study investigating healthy children, aged 5-8 years as to sodium and fluid intake by means of urinary sodium and creatinine from multiple samples taken in different days in order to characterize them in lower/higher sodium and lower/higher fluid intake. Both SBP and DBP (by multiple office blood pressure measurements) were used as outcome measures. RESULTS: Three hundred and thirty-nine healthy, nonoverweight children (51.6% boys) with a median age of 5.7 years old (IQR: 5.3-6.2) participated in the study but only 223 could be analyzed. Among children with higher sodium intake, those introducing more fluids, showed a significantly lower blood pressure (both systolic and diastolic) compared with those with lower fluid intake: systolic 86.0 ±â€Š8.5 vs. 90.0 ±â€Š8.1 mmHg; P = 0.014 and diastolic: 53.8 ±â€Š4.9 vs. 58.6 ±â€Š6.6 mmHg; P < 0.0001. CONCLUSION: An increased fluid intake is associated with a reduced blood pressure possibly by increasing renal sodium excretion. We speculate that this simple, highly acceptable, inexpensive, and harmless measure might have a role in preventing and/or minimizing the epidemics of hypertension and of its related morbidities both in children and in adults.

Bloody Diarrhea and Shiga Toxin-Producing Escherichia coli Hemolytic Uremic Syndrome in Children: Data from the ItalKid-HUS Network.

OBJECTIVE: To analyze the results of an enhanced laboratory-surveillance protocol for bloody diarrhea aimed at identifying children with Shiga toxin-producing Escherichia coli (STEC) infection early in the course of the disease toward the early identification and management of patients with hemolytic uremic syndrome (HUS). STUDY DESIGN: The study (2010-2019) involved a referral population of 2.3 million children. Stool samples of patients with bloody diarrhea were screened for Shiga toxin (Stx) genes. Positive patients were rehydrated and monitored for hemoglobinuria until diarrhea resolved or STEC-HUS was diagnosed. RESULTS: A total of 4767 children were screened; 214 (4.5%) were positive for either Stx1 (29.0%) or Stx2 (45.3%) or both Stx1+2 (25.7%); 34 patients (15.9%) developed STEC-HUS (0.71% of bloody diarrheas). Hemoglobinuria was present in all patients with HUS. Patients with Stx2 alone showed a greater risk of STEC-HUS (23.7% vs 12.7%) and none of the patients with Stx1 alone developed HUS. During the same period of time, 95 other patients were diagnosed STEC-HUS but were not captured by the screening program (26 had nonbloody diarrhea, 11 came from areas not covered by the screening program, and 58 had not been referred to the screening program, although they did meet the inclusion criteria). At HUS presentation, serum creatinine of patients identified by screening was significantly lower compared with that of the remaining patients (median 0.9 vs 1.51 mg/dL). CONCLUSIONS: Nearly 1% of children with bloody diarrhea developed STEC-HUS, and its diagnosis was anticipated by the screening program for Stx. The screening of bloody diarrhea for Stx is recommended, and monitoring patients carrying Stx2 with urine dipstick for hemoglobinuria is suggested to identify the renal complication as early as possible.

Risk of Atypical HUS Among Family Members of Patients Carrying Complement Regulatory Gene Abnormality.

INTRODUCTION: Atypical hemolytic uremic syndrome (aHUS) is mainly due to complement regulatory gene abnormalities with a dominant pattern but incomplete penetrance. Thus, healthy carriers can be identified in any family of aHUS patients, but it is unpredictable if they will eventually develop aHUS. METHODS: Patients are screened for 10 complement regulatory gene abnormalities and once a genetic alteration is identified, the search is extended to at-risk family members. The present cohort study includes 257 subjects from 71 families: 99 aHUS patients (71 index cases + 28 affected family members) and 158 healthy relatives with a documented complement gene abnormality. RESULTS: Fourteen families (19.7%) experienced multiple cases. Over a cumulative observation period of 7595 person-years, only 28 family members carrying gene mutations experienced aHUS (overall penetrance of 20%), leading to a disease rate of 3.69 events for 1000 person-years. The disease rate was 7.47 per 1000 person-years among siblings, 6.29 among offspring, 2.01 among parents, 1.84 among carriers of variants of uncertain significance, and 4.43 among carriers of causative variants. CONCLUSIONS: The penetrance of aHUS seems a lot lower than previously reported. Moreover, the disease risk is higher in carriers of causative variants and is not equally distributed among generations: siblings and the offspring of patients have a much greater disease risk than parents. However, risk calculation may depend on variant classification that could change over time.

Kidney transplant in patients with atypical hemolytic uremic syndrome in the anti-C5 era: single-center experience with tailored Eculizumab.

RATIONALE AND OBJECTIVE: Patients with atypical hemolytic uremic syndrome (aHUS) have long been considered ineligible for kidney transplantation (KTx) in several centers due to the high risk of disease recurrence, graft loss and life-threatening complications. The availability of Eculizumab (ECU) has now overcome this problem. However, the best approach towards timing, maintenance schedule, the possibility of discontinuation and patient monitoring has not yet been clearly established. STUDY DESIGN: This is a single center case series presenting our experience with KTx in aHUS. SETTING AND PARTICIPANTS: This study included 26 patients (16 females) with a diagnosis of aHUS, who spent a median of 5.5 years on kidney replacement therapy before undergoing KTx. We compared the aHUS relapse rate in three groups of patients who underwent KTx: patients who received no prophylaxis, patients who underwent plasma exchange, those who received Eculizumab prophylaxis. Complement factor H-related disease was by far the most frequent etiology (n = 19 patients). RESULTS: Untreated patients and patients undergoing pre-KTx plasma exchange prophylaxis had a relapse rate of 0.81 (CI 0.30-1.76) and 3.1 (CI 0.64-9.16) events per 10 years cumulative observation, respectively, as opposed to 0 events among patients receiving Eculizumab prophylaxis. The time between Eculizumab doses was tailored based on classic complement pathway activity (target to < 30%). Using this strategy, 12 patients are currently receiving  Eculizumab every 28 days, 5 every 24-25 days, and 3 every 21 days. CONCLUSION: Our experience supports the prophylactic use of Eculizumab in patients with a previous history of aHUS undergoing KTx, especially when complement dysregulation is well documented by molecular biology.

Haploidentical Hematopoietic Stem Cell Transplant Complicated by Atypical Hemolytic Uremic Syndrome and Kidney Transplant From the Same Donor With No Immunosuppression but C5 Inhibition.

BACKGROUND: Atypical hemolytic uremic syndrome (aHUS) is life-threatening condition particularly when complicating allograft hematopoietic stem cell transplant (HSCT). In the past, the outcome was very poor with the majority of patients reaching end-stage renal disease or dying with little or no chances of kidney transplant (KTx) due to the high risk of relapse. The availability of C5 inhibition has opened up significant therapeutic opportunities and has improved the outcome particularly if complement dysregulation (CD) is the underlying pathogenetic mechanism. METHODS: We describe a peculiar case of a girl with aHUS complicating HSCT and her subsequent successful KTx received from the same donor thus performed without immunosuppression but anti-C5 inhibition. RESULTS: Soon after HSCT performed for acute lymphoblastic leukemia, the patient developed a TMA due to CD and reached end-stage renal disease. After 2 years on dialysis, the patient received a KTx from her father who was already the HSCT donor. Given the full chimerism, no immunosuppressive agent was prescribed except a short (2 days) course of steroids and eculizumab to prevent aHUS relapse. Nine months after the KTx, the patient is well with normal renal function, no immunosuppression and continues eculizumab prevention of aHUS (1 infusion every 21 days). CONCLUSIONS: All patients with transplant-associated thrombotic microangiopathy should be screened for the causes of CD. C5 inhibition with eculizumab is an important therapeutic resource to manage this complication. When KTx is necessary, immunosuppression can be safely withhold in case of same donor for both grafts and documented full chimerism.

A simple prognostic index for Shigatoxin-related hemolytic uremic syndrome at onset: data from the ItalKid-HUS network.

Shigatoxin Escherichia coli-related hemolytic uremic syndrome (eHUS) is a severe thrombotic microangiopathy (TMA) burdened by life-threatening complications and long-term sequelae. Since hemoconcentration is associated with worse outcome, we tried to develop a reliable and easy-to-calculate index for predicting complications and sequelae based on hemoglobin (Hb) at presentation. The first laboratory examinations with signs of TMA in eHUS patients were analyzed in relation to the outcomes with the receiver operating characteristic curves and their areas under the curve (AUC) for Hb and creatinine (sCr). A total of 197 eHUS patients were identified of whom 24% did not have anemia at presentation. Hb level was the best predictor of a poor outcome (AUC 0.67) but the combination of Hb with sCr, in the formula [(Hb in g/dL + (sCr in mg/dL × 2)], showed an even better AUC of 0.75. The described scoring system was also strongly associated and predictive of all complications and health care needs (8% of patients with scoring > 13 died or entered a permanent vegetative state compared with 0% of those with ≤ 13).Conclusion: The presented score is a simple and early predictor of both short- and long-term outcomes and identifies patients who should undergo rapid volume expansion to counteract hemoconcentration, the spreading of microvascular thrombosis, and the consequent increased organ damage. What is Known: • In eHUS, hemoconcentration is associated with worse short- and long-term outcome. • A prognostic index to identify patients at higher risk for complications at presentation is not available. What is New: • We developed a simple and early prognostic index for eHUS outcome with the combination of Hb and sCr at onset, in the following formula [(Hb in g/dL + (sCr in mg/dL × 2)]. • The proposed HUS Severity Score can promptly identify patients with good outcome and those with high risk of worse short- and long-term outcome.

Serum creatinine during physiological perinatal dehydration may estimate individual nephron endowment.

It is well known that the nephron endowment of healthy subjects is highly variable and that individual nephron mass has potentially important implications both in health and disease. However, nephron count is technically impossible in living subjects. Based on the observation of an increase in serum creatinine (sCr) in otherwise healthy newborns with solitary kidney during the physiological perinatal dehydration, we hypothesized that perinatal sCr might be helpful in identifying healthy subjects with a reduced nephron mass. In the framework of a study on blood pressure in babies (NeoNeph), sCr of normal Caucasian neonates was determined 48-96 h after birth and their association with a family history of arterial hypertension (AH) was analyzed. SCr was determined in 182 normal newborns (90 males) at a mean of 61 ± 8 h after birth (range 46-82). Newborns with paternal AH had a higher mean sCr (0.97 + 0.28 mg/dL) then newborns without paternal AH (0.73 + 0.28 mg/dL; p = 0.006). No differences in mean sCr were found in relation with mother or grandparent's history of AH. CONCLUSION: The association between parental AH and high sCr during perinatal dehydration supports the hypothesis that the latter is a promising tool for identifying normal subjects with a reduced nephron mass with potential important implications in prevention and in understanding the individual outcome of renal and extrarenal diseases (including AH). What is Known: • Nephron endowment of healthy subjects is highly variable and individual nephron mass has potentially important implications both in health and disease however nephron count is not feasible in living subjects. What is New: • Serum creatinine during perinatal dehydration is a possible biomarker for identifying normal subjects with a reduced nephron mass.

Complement functional tests for monitoring eculizumab treatment in patients with atypical hemolytic uremic syndrome: an update.

BACKGROUND: Atypical hemolytic uremic syndrome (aHUS) is a thrombotic microangiopathy (TMA) characterized by platelet consumption, hemolysis, and organ damage. Eculizumab (ECU), a humanized antibody that blocks complement activity, has been successfully used in aHUS, but the best treatment schedule is not yet clear. METHODS: Here, we report our experience with ECU maintenance treatment and the interval between subsequent doses being extended based on global classical complement pathway (CCP) activity aimed at <30% for maintaining aHUS into remission. RESULTS: We report on 38 patients with aHUS, 13 children, 21 female, with a median age of 25.0 years (range 0.5-60) at disease onset treated with ECU standard schedule for a median of 2.6 months (range 0.4-24.6). Once stable TMA remission was obtained, the interval between ECU doses was extended based on complement function, with a target CCP activity of <30%. With this approach, 22 patients regularly receive ECU infusion every 28 days and 16 every 21. During a median observation period on ECU, an extended interval of 26.9 months (range 0.8-80.9), with a cumulative observation period of 1,208 months, none of the patients relapsed. CONCLUSION: Monitoring complement activity allows a safe reduction in the frequency of ECU administration in aHUS while keeping the disease in remission.

Bioimpedance-based rather than weight-based ultrafiltration prescription for children on maintenance hemodialysis
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The determination of dry weight (DW) in young children on hemodialysis (HD) remains challenging. Bioimpedance analysis (BIA) is a potentially helpful means of estimating the need for ultrafiltration and monitoring body fluids in patients on renal replacement therapy, but its role has not yet been clearly defined. The aim of this paper is to share our experience of prescribing ultrafiltration on the basis of BIA parameters alone. The body weight (BW), resistance (Rx), and reactance (Xc) of a 3-year-old girl on chronic HD were recorded pre- and post-HD over a period of 16 months. The BIA parameter that best correlated with actual ultrafiltration (the difference between pre- and post-HD BW) was identified, and the equivalence between actual ultrafiltration and changes in Xc was derived to obtain the following equation: 1 ohm of Xc = 27.4 g of ultrafiltration. Finally, during 21 consecutive HD sessions, ultrafiltration was exclusively prescribed on the basis of the derived equation (BIA-based prescription) after having defined a target post-HD Xc of 45 ohm. The BIA-based prescription period was compared with 21 consecutive HD sessions in which ultrafiltration was prescribed using the conventional approach based on BW (BW-based prescription). Comparison of BIA-based and BW-based ultrafiltration prescription showed significantly fewer HD sessions complicated by hypotension (19 vs. 50%) or by the need for reinfusion (5 vs. 50%), and a better overall quality of HD sessions (86 vs. 37%). No difference in blood pressure was observed, and no acute fluid overload event was detected in either period. BIA-based ultrafiltration seems to be safe, feasible, and effective. The described approach can be particularly useful in the case of patients with problems in setting or maintaining the correct DW.
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Late Onset Cobalamin Disorder and Hemolytic Uremic Syndrome: A Rare Cause of Nephrotic Syndrome.

Hemolytic uremic syndrome (HUS) is an unrare and severe thrombotic microangiopathy (TMA) caused by several pathogenetic mechanisms among which Shiga toxin-producing Escherichia coli infections and complement dysregulation are the most common. However, very rarely and particularly in neonates and infants, disorders of cobalamin metabolism (CblC) can present with or be complicated by TMA. Herein we describe a case of atypical HUS (aHUS) related to CblC disease which first presented in a previously healthy boy at age of 13.6 years. The clinical picture was initially dominated by nephrotic range proteinuria and severe hypertension followed by renal failure. The specific treatment with high dose of hydroxycobalamin rapidly obtained the remission of TMA and the complete recovery of renal function. We conclude that plasma homocysteine and methionine determinations together with urine organic acid analysis should be included in the diagnostic work-up of any patient with TMA and/or nephrotic syndrome regardless of age.

Acquired Complement Regulatory Gene Mutations and Hematopoietic Stem Cell Transplant-Related Thrombotic Microangiopathy.

Hematopoietic stem cell transplant-related thrombotic microangiopathy (HSCT-TMA) is a severe complication whose pathophysiology is unknown. We describe 6 patients in which the disease was associated with complement regulatory gene abnormalities received from their respective donors. It is suggested that mutated and transplanted monocyte-derived cells are responsible for production of abnormal proteins, complement dysregulation, and, ultimately, for the disease. This observation might have important drawbacks as far as HSCT-TMA pathophysiology and treatment are concerned.

Epidemiology of haemolytic uremic syndrome in children. Data from the North Italian HUS network.

UNLABELLED: Despite the severity of HUS and the fact that it represents a leading cause of acute kidney injury in children, the general epidemiology of HUS is all but well documented. The present study provides updated, population-based, purely epidemiological information on HUS in childhood from a large and densely populated area of northern Italy (9.6 million inhabitants, 1.6 million children). We systematically reviewed the files concerning patients with STEC-HUS and atypical HUS (aHUS) over a 10-year observation period (January 2003-December 2012). We included all incident cases with a documented first episode of HUS before the age of 18 years. We identified 101 cases of HUS during the 10 years. The overall mean annual incidence was 6.3 cases/million children aged <18 years (range 1.9-11.9), and 15.7/million of age-related population (MARP) among subjects aged <5 years; aHUS accounted for 11.9 % of the cases (mean incidence 0.75/MARP). The overall case fatality rate was 4.0 % (3.4 % STEC-HUS, 8.3 % aHUS). CONCLUSION: Given the public health impact of HUS, this study provides recent, population-based epidemiological data useful for healthcare planning and particularly for estimating the financial burden that healthcare providers might have to face in treating HUS, whose incidence rate seems to increase in Northern Italy. WHAT IS KNOWN: • HUS is a rare disease, but it represents the leading cause of acute kidney injury in children worldwide. • STEC-HUS (also called typical, D + HUS) is more common compared to atypical HUS, but recent, population-based epidemiological data (incidence) are scanty. What is New: • Comprehensive, population-based epidemiological data concerning both typical and atypical HUS based on a long observational period.

Early Volume Expansion and Outcomes of Hemolytic Uremic Syndrome.

BACKGROUND: Hemolytic uremic syndrome associated with Shiga toxin-producing Escherichia coli (STEC-HUS) is a severe acute illness without specific treatment except supportive care; fluid management is concentrated on preventing fluid overload for patients, who are often oligoanuric. Hemoconcentration at onset is associated with more severe disease, but the benefits of volume expansion after hemolytic uremic syndrome (HUS) onset have not been explored. METHODS: All the children with STEC-HUS referred to our center between 2012 and 2014 received intravenous infusion targeted at inducing an early volume expansion (+10% of working weight) to restore circulating volume and reduce ischemic or hypoxic tissue damage. The short- and long-term outcomes of these patients were compared with those of 38 historical patients referred to our center during the years immediately before, when fluid intake was routinely restricted. RESULTS: Patients undergoing fluid infusion soon after diagnosis showed a mean increase in body weight of 12.5% (vs 0%), had significantly better short-term outcomes with a lower rate of central nervous system involvement (7.9% vs 23.7%, P = .06), had less need for renal replacement therapy (26.3% vs 57.9%, P = .01) or intensive care support (2.0 vs. 8.5 days, P = .02), and needed fewer days of hospitalization (9.0 vs 12.0 days, P = .03). Long-term outcomes were also significantly better in terms of renal and extrarenal sequelae (13.2% vs 39.5%, P = .01). CONCLUSIONS: Patients with STEC-HUS had great benefit from early volume expansion. It is speculated that early and generous fluid infusions can reduce thrombus formation and ischemic organ damage, thus having positive effects on both short- and long-term disease outcomes.

Hemoconcentration: a major risk factor for neurological involvement in hemolytic uremic syndrome.

BACKGROUND: Shigatoxin-associated hemolytic uremic syndrome (STEC-HUS) is a common thrombotic microangiopathy (TMA) in which central nervous system (CNS) involvement is responsible for the majority of deaths and for severe long-term sequelae. We have analyzed the role of hemoconcentration in disease severity. METHODS: This was a retrospective review of the records and laboratory data at presentation of all patients with STEC-HUS cases (n = 61) over a 10-year period. The patients were grouped into three severity classes: group A, comprising patients who did not require dialysis; group B, patients who were dialyzed without CNS involvement; group C, patients with CNS involvement. RESULTS: Patients with CNS involvement (group C) had a higher mean hemoglobin level (11.2 ± 2.3 g/dL) than those of group A or B ( 9.4 ± 2.1 and 7.5 ± 1.9 g/dL, respectively; p < 0.0001). We also observed that the higher the initial hemoglobin level, the more severe the long-term renal damage (p < 0.007). CONCLUSIONS: In patients with STEC-HUS, hemoconcentration and hypovolemia may be responsible for more severe ischemic organ damage (both short and long term) at disease onset, and these signs should be regarded as risk factors for CNS damage and for more severe TMA. Therefore, we recommend that hydration status should be actively monitored in HUS patients and that dehydration, when diagnosed, should be promptly corrected.

Co-infection in children with bloody diarrhea caused by Shiga toxin-producing Escherichia coli: data of the North Italian HUS Network.

Hemolytic-uremic syndrome (HUS) is an important cause of acute kidney injury in children often caused by Shiga toxin-producing Escherichia coli (STEC) enterocolitis. In a screening program for STEC infection in children with bloody diarrhea in northern Italy for early diagnosis of HUS, co-infection with Salmonella or Campylobacter was documented in as many as 35.6% of Shiga toxin-positive patients. It is speculated that infection by Salmonella or Campylobacter may increase the risk of STEC enterocolitis and therefore of HUS. The isolation of microorganisms (other then STEC) in HUS should not be necessarily regarded as the etiological agent for the thrombotic microangiopathy.

Cryptic activity of atypical hemolytic uremic syndrome and eculizumab treatment.

Atypical hemolytic uremic syndrome (aHUS) is a rare, life-threatening disease often related to uncontrolled complement activation. The use of eculizumab has changed the management and the outcome of aHUS, becoming the frontline treatment of the acute disease and for the prevention of relapses. We report the case of a male patient with aHUS due to complement factor H gene mutation who was shifted from plasmatherapy to eculizumab for preventing disease relapses. The shift to eculizumab was associated with a significant decrease in proteinuria, revealing disease activity otherwise unsuspected, being the classic criteria of disease activity (platelet, haptoglobin, LDH, schistocytes), all in the normal range.The condition of proteinuria as the only sign of thrombotic microangiopathy activity is here designated as "cryptic activity of aHUS."