Renal dysfunction in patients with sickle cell anemia or sickle cell trait

First Experience in Living Liver Donation From Donors With Sickle Cell Trait

Living donor liver transplantation is the main source of organs in the Middle East. Therefore, well balanced criteria are needed to avoid unnecessary exclusion of potential donors, while prioritizing donor safety. We face a high incidence of sickle cell trait (SCT; and disease). Therefore, there is vast experience in general and cardiac surgeries in SCT carriers at our center. After studying their management in detail, we considered accepting SCT carriers as living liver donors, on an exceptional basis. This the first single-center case series of living donor liver transplantation with SCT.

Reduced blood pressure in sickle cell disease is associated with decreased angiotensin converting enzyme (ACE) activity and is not modulated by ACE inhibition

Background

Sickle cell disease (SCD) incurs vaso-occlusive episodes and organ damage, including nephropathy. Despite displaying characteristics of vascular dysfunction, SCD patients tend to present relatively lower systemic blood pressure (BP), via an unknown mechanism. We investigated associations between BP and renin-angiotensin-system (RAS) components in SCD and determined whether an inhibitor of angiotensin converting enzyme (ACE; often used to slow SCD glomerulopathy) further modulates BP and RAS components in a murine model of SCD.

Methods

BP was compared in human subjects and mice with/without SCD. Plasma angiotensin II, ACE and renin were measured by immunoassay. BP was reevaluated after treating mice with enalapril (25 mg/kg, 5x/week) for 5 weeks; plasma and organs were stored for angiotensin II and ACE activity measurement, and quantitative real-time PCR.

Results

Diastolic BP and systolic BP were significantly lower in patients and mice with SCD, respectively, compared to controls. Reduced BP was associated with increased plasma renin and markers of kidney damage (mice) in SCD, as well as significantly decreased plasma ACE concentrations and ACE enzyme activity. As expected, enalapril administration lowered BP, plasma angiotensin II and organ ACE activity in control mice. In contrast, enalapril did not further reduce BP or organ ACE activity in SCD mice; however, plasma angiotensin II and renin levels were found to be significantly higher in enalapril-treated SCD mice than those of treated control mice.

Conclusion

Relative hypotension was confirmed in a murine model of SCD, in association with decreased ACE concentrations in both human and murine disease. Given that ACE inhibition has an accepted role in decreasing BP, further studies should investigate mechanisms by which ACE depletion, via both Ang II-dependent and alternative pathways, could contribute to reduce BP in SCD and understand how ACE inhibition confers Ang II-independent benefits on kidney function in SCD.

Practice Patterns for the Acceptance of Medically Complex Living Kidney Donors with Hematuria, Sickle Cell Trait, Smoking, Illegal Drug Use, or Urological Issues: A Multinational Survey

Background  To review the practice patterns for the acceptance of medically complex living kidney donors (MCLKD) among the transplant providers of the international transplant community. Methods  We distributed a survey globally, through major international transplantation societies, among nephrologists and transplant surgeons (TS). The survey contained questions regarding potential donors with microscopic hematuria, sickle cell trait, renal cysts, kidney stones, smoking, or illegal drug use. Results  There were 239 respondents from 29 countries, including nephrologists (42%) and TS (58%). Although most respondents would investigate microscopic hematuria, one-third of them indicated they would decline these potential donors without investigation. Interestingly, most respondents accepted heavy smokers, intermittent illegal drug users (with advice to quit), and those with incidentally identified kidney stones, remote history of renal colic or simple renal cysts. We found multiple areas of consensus in practice with some interesting differences between nephrologists and TS. Conclusions  This survey highlights the practice patterns of the acceptance of MCLKDs among the international community. In the absence of clear guidelines, this survey provides additional information to counsel kidney donors with microscopic hematuria, sickle cell trait, renal cysts, kidney stones, heavy smoking, or illegal drug use.

Prevalence and Risk Factors for Microalbuminuria in Children with Sickle Cell Disease at King Abdulaziz University Hospital: A Retrospective Cross-sectional Study

Objectives: Previous studies have not addressed microalbuminuria in pediatric patients with sickle cell disease (SCD) in Jeddah, Saudi Arabia. This study aimed to determine the prevalence of microalbuminuria and to identify associated risk factors in children with SCD at King Abdulaziz University Hospital.

Results: Overall, 42.5% of the patients enrolled were Saudi Arabian and 51% were male. The mean age was 12.4 years, and the highest percentage (40%) was in the age group of 15-18 years. The prevalence of microalbuminuria was 9.6%, and hematuria was present in 8% of cases. The percentage of patients with hematuria was significantly higher in the microalbuminuria group (22.6%) than in the nonmicroalbuminuria group (6.5%; P = 0.007). The percentage of patients with acute chest syndrome was also higher in the microalbuminuria group (26%) than in the nonmicroalbuminuria group (8%; P = 0.005). The percentage of patients with gallbladder stones was higher in the microalbuminuria group (13%) than in the nonmicroalbuminuria group (2.4%; P = 0.014). However, the mean number of blood transfusions was higher in the nonmicroalbuminuria group than in the microalbuminuria group (P = 0.002). Sickle cell nephropathy manifests as microalbuminuria, begins at an early age, occurs in all types of SCD, and is associated with disease severity.

Sickle cell disease nephropathy: an update on risk factors and potential biomarkers in pediatric patients

One of the major chronic complications of sickle cell disease (SCD) is sickle cell nephropathy. The aim of this review is to discuss the pathophysiology, natural history, clinical manifestations, risk factors, biomarkers and therapeutic approaches for sickle cell nephropathy, focusing on studies with pediatric patients. The earliest manifestation of renal disease is an increase in the glomerular filtration rate. A finding that may also be observed in early childhood is microalbuminuria. Nephrin, KIM-1, VGFs, chemokines and renin-angiotensin system molecules have emerged as potential early markers of renal dysfunction in SCD. In regards to a therapeutic approach, renin-angiotensin system inhibitors and angiotensin receptor blockers seem to be effective for the control of albuminuria in adults with SCD, although new studies in children are needed. The precise moment to begin renoprotection in SCD patients who should be treated remains to be determined.

Prevalence and factors associated with renal dysfunction among children with sickle cell disease attending the sickle cell disease clinic at a tertiary hospital in Northwestern Tanzania

BACKGROUND

Little is known on how the interaction between Sickle Cell Disease (SCD) and renal insults caused by other coexisting conditions in Sub Saharan Africa such as urinary schistosomiasis, malnutrition and HIV affect the prevalence of renal dysfunction in children with SCD.

OBJECTIVES

To determine the prevalence and factors associated with renal dysfunction among children with SCD aged 6 months to 12 years attended at a tertiary hospital in Northwestern Tanzania.

METHODS

A cross sectional hospital-based study with a short follow up component of 3 months for 153 children with SCD was done to document demographics, clinical characteristics and features of renal dysfunction including urine dipstick albuminuria (>20mg/l) and eGFR (<60ml/ml/min/1.73m2). Other potential renal insults such as HIV infection and Schistosomiasis were also evaluated.

RESULTS

At enrollment, 48/153(31.37%) children had renal dysfunction declining to 31(20.3%) at 3 months follow up. Acute chest syndrome (OR 3.04, 95% CI [1.08-8.96], p = 0.044), severe anemia (OR 0.44, 95% CI [0.26-0.76],p = 0.003), urinary schistosomiasis (OR 7.43, 95% CI [2.10-26.32] p<0.002) and acute malnutrition (OR 4.92, 95% CI [1.29-18.84], p = 0.020). were associated with renal dysfunction.

CONCLUSION

Where prevalent, urinary schistosomiasis and acute malnutrition increase the risk for renal dysfunction in children with SCD. We recommend albuminuria routine screening in children with SCD especially those presenting with acute chest syndrome, severe anemia and features of acute malnutrition for early detection of renal dysfunction among children with SCD.

Sickle cell trait and renal disease among African American U.S. Army soldiers

Sickle cell trait and certain renal disorders are disproportionately prevalent among African American individuals, so a clear understanding of their association is important. We conducted a longitudinal study using the Stanford Military Data Repository to examine sickle cell trait in relation to the incidence of acute kidney injury (AKI) and chronic kidney disease (CKD). Our study population consisted of African American U.S. Army soldiers on active duty between January 2011 and December 2014. The cumulative incidence was 0·51% for AKI (236 cases out of 45 901 soldiers) and 0·56% for CKD (255 cases out of 45 882 soldiers). Discrete time logistic regression models adjusting for demographic-, military- and healthcare-related covariates showed that sickle cell trait was associated with significantly higher adjusted odds of both AKI [odds ratio (OR): 1·74; 95% confidence interval (CI): 1·17-2·59] and CKD (OR: 2·00; 95% CI: 1·39-2·88). Elevated odds of AKI and CKD were also observed in association with prior CKD and AKI, respectively, and with obesity and prior hypertension. Individuals with sickle cell trait and their providers should be aware of the possibility of increased risk of AKI and CKD to allow for timely intervention and possible prevention.

Sickle cell nephropathy: an update on pathophysiology, diagnosis, and treatment

Sickle cell nephropathy is a major complication of sickle cell disease. It manifests in different forms, including glomerulopathy, proteinuria, hematuria, and tubular defects, and frequently results in end-stage renal disease (ESRD). Different pathophysiologic mechanisms have been proposed to explain the development of nephropathy in SCD, where hemolysis and vascular occlusion are the main contributors in the manifestations of this disease. Markers of renal injury, such as proteinuria and tubular dysfunction, have been associated with outcomes among patients with sickle cell nephropathy and provide means for early detection of nephropathy and screening prior to progression to renal failure. In small-sized clinical trials, hydroxyurea has demonstrated to be effective in slowing the progression to ESRD. Dialysis and renal transplantation represent the last resort for patients with sickle cell nephropathy. Nevertheless, despite the availability of diagnostic and therapeutic strategies, sickle cell nephropathy remains a challenging and under-recognized complication for patients with sickle cell disease.

Congolese children with sickle cell trait may exhibit glomerular hyperfiltration: A case control study

BACKGROUND

The prevalence of sickle cell trait is extremely high in sub-Saharan Africa. Recent studies have reported the impact of sickle cell carriers on renal function. However, data on renal abnormalities in children with sickle cell trait in this part of the world are unknown. In this report, we assess the glomerular function of children with sickle cell trait (SCT).

METHODS

A case control study was conducted to assess the glomerular function in 43 Congolese children with sickle cell trait (Hb-AS) matched for age to 65 children with sickle cell anemia in steady state (Hb-SS) and 67 normal controls (Hb-AA).

RESULTS

There was a significant difference in the blood pressure levels between the Hb-AS group vs Hb-SS group (P<.05). The estimated glomerular filtration rate (eGFR) corrected for body surface area was increased in Hb-AS group compared to Hb-AA group, but there was no significant difference between the two groups (P=.48). At the same time, the eGFR was decreased, but no significantly so, in the Hb-AS group compared to the Hb-SS group (P=.19). The proportion of children with Hb-AS (16.3%) who had hyperfiltration was higher compared to the proportion (6.1%) found in the Hb-AA group, but lower compared to the proportion found in the Hb-SS group (30%). However, in both situations, the difference was not statistically significant. No case of proteinuria was detected in children with Hb-AS.

CONCLUSION

It appears that at least one of six children with SCT had hyperfiltration. The findings could form a basis for further studies on this renal physiology among SCT individuals in Africa.

Negative health implications of sickle cell trait in high income countries: from the football field to the laboratory

Worldwide, sickle cell trait is a highly prevalent gene carrier state. While generally a benign condition with a normal life expectancy, it is becoming increasingly clear that the sickle trait is associated with certain adverse outcomes. This article will focus on three of these outcomes, namely exertional rhabdomyolysis and sudden death, chronic renal dysfunction, and venous thromboembolism. In each case, the epidemiological evidence for the association is reviewed, together with the existing data on potential underlying mechanisms. Because newborn screening programmes for sickle cell anaemia also identify those with sickle cell trait, it is imperative that further studies determine what, if any, preventive measures can be taken to reduce the burden of these uncommon but potentially morbid complications in affected individuals.

Renal tubular dysfunction in sickle cell disease

BACKGROUND/AIMS

Kidney abnormalities are one of the main chronic complications of sickle cell disease (SCD). The aim of this study is to investigate the occurrence of renal tubular abnormalities among patients with SCD.

METHODS

This is a prospective study with 26 SCD adult patients in Brazil. Urinary acidification and concentration tests were performed using calcium chloride (CaCl2), after a 12h period of water and food deprivation. Fractional excretion of sodium (FENa), transtubular potassium gradient (TTKG) and solute free water reabsorption (TcH2O) were calculated. The SCD group was compared to a group of 15 healthy volunteers (control group).

RESULTS

Patient`s average age and gender were similar to controls. Urinary acidification deficit was found in 10 SCD patients (38.4%), who presented urinary pH >5.3 after CaCl2 test. Urinary osmolality was significantly lower in SCD patients (355 ± 60 vs. 818 ± 202 mOsm/kg, p=0.0001, after 12h period water deprivation). Urinary concentration deficit was found in all SCD patients (100%). FENa was higher among SCD patients (0.75 ± 0.3 vs. 0.55 ± 0.2%, p=0.02). The TTKG was higher in SCD patients (5.5 ± 2.5 vs. 3.0 ± 1.5, p=0.001), and TcH2O was lower (0.22 ± 0.3 vs. 1.1 ± 0.3L/day, p=0.0001).

CONCLUSIONS

SCD is associated with important kidney dysfunction. The main abnormalities found were urinary concentrating and incomplete distal acidification defect. There was also an increase in the potassium transport and decrease in water reabsorption, evidencing the occurrence of distal tubular dysfunction. .

Sickle trait in African-American hemodialysis patients and higher erythropoiesis-stimulating agent dose

African Americans require higher doses of erythropoiesis-stimulating agents (ESAs) during dialysis to manage anemia, but the influence of sickle cell trait and other hemoglobinopathy traits on anemia in dialysis patients has not been adequately evaluated. We performed a cross-sectional study of a large cohort of adult African-American hemodialysis patients in the United States to determine the prevalence of hemoglobinopathy traits and quantify their influence on ESA dosing. Laboratory and clinical data were obtained over 6 months in 2011. Among 5319 African-American patients, 542 (10.2%) patients had sickle cell trait, and 129 (2.4%) patients had hemoglobin C trait; no other hemoglobinopathy traits were present. Sickle cell trait was more common in this cohort than the general African-American population (10.2% versus 6.5%-8.7%, respectively, P<0.05). Among 5002 patients (10.3% sickle cell trait and 2.4% hemoglobin C trait) receiving ESAs, demographic and clinical variables were similar across groups, with achieved hemoglobin levels being nearly identical. Patients with hemoglobinopathy traits received higher median doses of ESA than patients with normal hemoglobin (4737.4 versus 4364.1 units/treatment, respectively, P=0.02). In multivariable analyses, hemoglobinopathy traits associated with 13.2% more ESA per treatment (P=0.001). Within subgroups, sickle cell trait patients received 13.2% (P=0.003) higher dose and hemoglobin C trait patients exhibited a similar difference (12.9%, P=0.12). Sensitivity analyses using weight-based dosing definitions and separate logistic regression models showed comparable associations. Our findings suggest that the presence of sickle cell trait and hemoglobin C trait may explain, at least in part, prior observations of greater ESA doses administered to African-American dialysis patients relative to Caucasian patients.

Kidney function, urinalysis abnormalities and correlates in equatorial Africans with sickle cell disease

BACKGROUND

Little is known about the renal profiles of individuals with sickle cell disease (SCD) in equatorial Africa, the global epicenter of SCD. We evaluated the kidney function, urinalysis abnormalities and their correlates in a group of Cameroonians homozygous for SCD.

METHODS

This was a cross-sectional study of 4-month duration involving 72 homozygous SCD patients (39 men, 54%), recruited during routine visit or vaso-occlusive crisis at the Yaoundé Central Hospital in Cameroon. Clinical and laboratory data were used to evaluate the renal and urinalysis parameters, and potential effects of SCD-related clinical and hematological variables on those parameters investigated through linear and logistic regression models.

RESULTS

The mean serum creatinine increased with increasing age, translating into a decreasing estimated glomerular filtration rate (eGFR) with age (P < 0.001). One patient (1.4%) had an eGFR of <60 mL/min and nine others (12.5%) had 60 ≤ eGFR ≤ 90 mL/min. The eGFR was lower in women and decreased with increasing systolic blood pressure. The prevalence of proteinuria (>200 mg/g) was 93% and the main urinalysis abnormalities were leukocyturia (77.8%), albuminuria (40.3%), hematuria (13.9%) and cristalluria (9.7%). None of the predictive clinical, hematological and urinary factors studied was associated with proteinuria or albuminuria, while hematuria and leukocyturia were associated with increasing age and male gender.

CONCLUSIONS

Cameroonians homozygous for SCD present a high prevalence of proteinuria and urinalysis abnormalities, and a slight renal impairment. Age, blood pressure variables and gender seem to be the main determinants. Urinalysis abnormalities and kidney function assessment should be an active pursuit in women with SCD.

Biochemical indicator of sickle cell disease: preliminary report from India

Blood biochemistry has significant effect on pathophysiology of human body. Recently few studies found the association of biochemical abnormalities in sickle cell patients. Sickle cell disease showed clinical variability where African ancestors have severe phenotype than Indian sicklers. Our aim was to evaluate the biochemicals in sickle cell patients and their effect on severity. Here we present the comparative biochemical levels in sickle cell patients as well as controls. Sickle cell patients diagnosed by HPLC and biochemical analysis done by Beckman-auto analyzer. T test applied for statistical analysis. Result showed the renal abnormality lesser in patients and related biochemical within the normal range and statistically not significant. Electrolytes, hepatic enzymes, alkaline phosphatase and glucose were elevated and statistically significant (P value <0.05). Observation of the study concludes the biochemical abnormality play a significant role in sickle cell patient's physiopathology and can be used to management of the disease.

Sickle cell nephropathy: challenging the conventional wisdom

This review explores the current model of sickle cell nephropathy and the limitations of the model. Renal abnormalities are common complications of sickle cell disease (SCD). Beginning in childhood, patients with SCD develop a urinary concentrating defect resulting in polyuria and a predisposition to nocturnal enuresis and dehydration. The current model of sickle cell nephropathy suggests that destruction of the renal medulla induces production of renal vasodilating substances that feedback to the glomerulus causing hyperfiltration. Hyperfiltration leads to glomerulosclerosis and proteinuria, with eventual reduction in kidney function. The crucial steps of vasodilating substance production and hyperfiltration in children with SCD have not been proven. Treatment of sickle cell nephropathy is aimed at the reduction of proteinuria with angiotensin converting enzyme inhibitors or angiotensin receptor blockers. Hydroxyurea and chronic transfusion therapy may also alter the progression of sickle cell nephropathy in children. Further studies are needed to identify an accurate model and effective treatments for sickle cell nephropathy.

New insights on pathophysiology, clinical manifestations, diagnosis, and treatment of sickle cell nephropathy

Sickle cell nephropathy is one of the main chronic complications of sickle cell disease (SCD), the most common of the hematological hereditary disorders. Several studies have been performed since the first description of SCD 100 years ago to investigate the mechanisms of kidney involvement in this disease. It has been demonstrated that both glomerular and tubular compartments can be damaged as a direct consequence of SCD, including renal function loss, concentration and acidification deficits, and glomerulopathies. This article highlights the aspects of sickle cell nephropathy pathophysiology and clinical manifestations and describes the most recent advances in the diagnosis and treatment of this disorder.

The role of infection in the pathogenesis of vaso-occlusive crisis in patients with sickle cell disease

Sickle cell disease (SCD) is characterized by recurrent vaso-occlusive crisis (VOC). Patients with SCD have impaired immunity and are thus predispose to infections. The vast majority of SCD patients live in underdeveloped nations with high prevalence and transmission rates of infections. This makes the SCD patients prone to infections, which frequently precipitate VOC. We reviewed the role of infection in the pathogenesis of VOC, taking into consideration all potential mechanisms from previous studies and hypothetical perspectives. The potential mechanisms through which infections may lead to VOC involve several pathological changes including pneumonitis, pyrexia, acute phase reaction, hypercoagulability, neutrophilia, eosinophilia, thrombocytosis, bronchospasm, red cell cytopathic and membrane changes, auto-antibodies mediated red cell agglutination and opsonization, diarrhoea and vomiting, which may act singly or in concert to cause red cell sickling. These changes can induce sickling directly or indirectly through their adverse effects on Hb oxygenation and polymerization, hydration, blood viscosity, red cell metabolism, procoagulant activation, intercellular adherence and aggregation, culminating in VOC. There is therefore the need to ameliorate the burden of infection on SCD through immunization, prophylactic and therapeutic use of antimicrobials, barrier protection and vector control in communities with high prevalence of SCD.

Higher rates of hemolysis are not associated with albuminuria in Jamaicans with sickle cell disease

BACKGROUND

Albuminuria is a marker of glomerular damage in Sickle Cell Disease (SCD). In this study, we sought to determine the possible predictors of albuminuria in the two more prevalent genotypes of SCD among the Jamaica Sickle Cell Cohort Study participants.

METHODS

An age-matched cohort of 122 patients with HbSS or HbSC genotypes had measurements of their morning urine albumin concentration, blood pressure, body mass index, haematology and certain biochemistry parameters done. Associations of albuminuria with possible predictors including hematological parameters, reticulocyte counts, aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) levels were examined using multiple regression models.

RESULTS

A total of 122 participants were recruited (mean age 28.6 years ±2.5 years; 85 HbSS, 37 HbSC). 25.9% with HbSS and 10.8% with HbSC disease had microalbuminuria (urine albumin/creatinine ratio  =  30-300 mg/g of creatinine) whereas 16.5% of HbSS and 2.7% of HbSC disease had macroalbuminuria (urine albumin/creatinine ratio>300 mg/g of creatinine). Mean arterial pressure, hemoglobin levels, serum creatinine, reticulocyte counts and white blood cell counts were statistically significant predictors of albuminuria in HbSS, whereas white blood cell counts and serum creatinine predicted albuminuria in HbSC disease. Both markers of chronic hemolysis, i.e. AST and LDH levels, showed no associations with albuminuria in either genotype.

CONCLUSIONS

Renal disease, as evidenced by excretion of increased amounts of albumin in urine due to a glomerulopathy, is a common end-organ complication in SCD. It is shown to be more severe in those with HbSS disease than in HbSC disease. Rising blood pressure, lower hemoglobin levels and higher white blood cell counts are hints to the clinician of impending renal disease, whereas higher rates of hemolysis do not appear to play a role in this complication of SCD.

High prevalence of sickle cell trait in African Americans with ESRD

Sickle cell trait (HbAS) associates with impaired urinary concentration, hematuria, and renal papillary necrosis, but its prevalence among African Americans with ESRD is unknown. We performed a cross-sectional study reviewing available hemoglobin phenotypes for 188 of 206 adult African-American patients receiving renal replacement therapy in four dialysis units. Results from the state newborn screening program in corresponding counties provided the local population prevalence of sickle trait among African Americans. Compared with the general African-American population, HbAS was twice as common among African Americans with ESRD (15% versus 7%, P < 0.001). Prevalence of hemoglobin C trait (HbAC) was similarly more common (5% versus 2%, P < 0.01). The higher prevalence of HbAS and HbAC in the ESRD population raises the possibility that these hemoglobinopathies contribute to a decline in kidney function, either alone or in conjunction with other known risk factors for renal disease. The potential effect of HbAS on the development and progression of CKD and its effect on the course and management of patients with ESRD deserve further study.

Sickle-cell trait: novel clinical significance

There is a long-standing controversy in the literature as to whether sickle-cell trait (SCT) should be viewed as a benign carrier state or as an intermediate disease phenotype. Because SCT is routinely detected by neonatal screening for sickle-cell disease, it becomes imperative that consensus on this issue be achieved in order to provide the best medical advice to affected individuals. The issue of selective screening in the post-neonatal period was thrust into the limelight recently by the National Collegiate Athletic Association's recommendation that its member colleges and universities test student-athletes to confirm their carrier status if not already known. The stated goal of this recommendation was to prevent exercise-related sudden death in athletes with SCT. We review some of the reported complications of SCT for which new information has emerged, focusing particularly on venous thromboembolism and renal manifestations.

Murine glutathione S-transferase A1-1 in sickle transgenic mice

Patients with sickle cell anemia exhibit mild to moderate renal and liver damage. Glutathione S-transferase A1-1 is produced during kidney and liver damage. We hypothesized that cellular damage in sickle transgenic mice would lead to increased serum and urine murine glutathione S-transferase A1-1 levels. Levels of murine glutathione S-transferase A1-1 in the serum and urine of S+S-Antilles, NY1DD, and control mice were measured by ELISA, which revealed that the serum of S+S-Antilles mice, relative to controls, had elevated levels of murine glutathione S-transferase A1-1 (P = 0.005) as did NY1DD mice (P = 0.02, baseline vs. 2-day hypoxia). Serum liver enzymes, such as aspartate amino transferase and alanine amino transferase, as well as lactate dehydrogenase were increased in S+S-Antilles mice relative to controls (P = 0.000006, P = 0.0003, and P = 0.029, respectively). Urine murine glutathione S-transferase A1-1 of S+S-Antilles mice, as well as NY1DD mice under hypoxic stress, was not significantly different from controls. Murine glutathione S-transferase class-mu was measured by ELISA in the urine of sickle transgenic mice and control mice to define the location of tubular damage at the proximal convoluted tubule; murine Glutathione S-transferase class-mu was below the limit of detection. These findings suggest that elevated levels of murine glutathione S-transferase A1-1 in the serum reflect release during liver damage and that proximal tubular damage does not lead to appreciable urinary murine glutathione S-transferase A1-1.

Comparison of renal function markers in Kuwaiti patients with sickle cell disease

BACKGROUND

Proteinuria is a common manifestation of renal disease which is a significant cause of morbidity in patients with sickle cell disease (SCD).

OBJECTIVE

To evaluate and compare cystatin C, beta(2)-microglobulin, and creatinine as markers of renal disease in relation to the degree of proteinuria and other complications of SCD.

METHODS

24 h urine collections were used for estimation of urine protein and creatinine clearance in 59 patients with SCD. Results were correlated with plasma cystatin C, beta(2)-microglobulin, creatinine, glomerular filtration rate (GFR; derived from plasma creatinine by Cockcroft-Gault, MDRD formulae, and calculated cystatin C clearance), and clinical and haematological variables.

RESULTS

Comparing the different methods of GFR, the proportion of patients with hyperfiltration (GFR >140 ml/min) were 30.5% (MDRD), 44.1% (Cockcroft-Gault), and 10.2 % (calculated cystatin C clearance). Cystatin C was the most consistent marker of hyperfiltration. The endogenous markers of GFR showed an increasing trend with increasing proteinuria, but haematological variables were not correlated with cystatin C, beta(2)-microglobulin, or plasma creatinine. Urine protein excretion was correlated with age (r = 0.33) and significant proteinuria was present in 13.6% of patients. Patients with proteinuria had lower haemoglobin concentration (p = 0.027) than those without proteinuria but HbF was not related to the degree of proteinuria or to markers of GFR.

CONCLUSIONS

Markers of GFR show variable ability to identify hyperfiltration in patients with SCD, but cystatin C is the best endogenous marker. Proteinuria is associated with age, haemoglobin, and abnormalities of GFR. Routine screening is recommended to allow for early detection and intervention.

Hb Amsterdam [alpha32(B13)Met--Ile (alpha2)]: a new unstable variant associated with an alpha-thalassemia phenotype and a new African polymorphism

We have characterized a new abnormal hemoglobin (Hb) at position 32 of the alpha-globin chain. The proband, a 38-year-old woman of Surinamese Black ancestry, was referred to the Academic Hospital in Amsterdam, The Netherlands, after 3 years of Prednisone treatment in Surinam. Kidney failure was diagnosed at the Nephrology Department, Free University Medical Center, Amsterdam, The Netherlands; the cortisone treatment was interrupted and dialysis was started. At this stage, a microcytic hypochromic anemia was observed with high reticulocyte (40%) and ferritin (500 microg/L) levels, and hemoglobinopathy was suspected. No abnormal bands were visible on alkaline electrophoresis and high performance liquid chromatography (HPLC). The Hb A2 level was normal (2.7%) and the erythrocyte count was low (3.59 x 10(12)/L) with a normal haptoglobin level (68 mg/100 mL). None of the common alpha-thalassemia (thal) deletion defects were present. The beta-globin gene sequence was normal but the alpha2-globin gene sequence revealed an ATG-->ATA transition at codon 32, changing the methionine into an isoleucine residue. The mutation, called Hb Amsterdam, was observed in the mother of the proband, who was also heterozygous for the--alpha3.7-thal deletion and affected by a moderate microcytic hypochromic anemia. Both Hb Amsterdam and the--alpha(-3.7) allele were found in association with a new polymorphism, IVS-I-39 (C-->T), previously observed in our laboratory in seven patients of African origin, on both the alpha1 and alpha2 genes. In addition, Hb Amsterdam was also associated with the common African alpha2 polymorphism (G-->CTCGGCCC at position 7238 and T-->G at position 7174). Hb Amsterdam is the first mutation ever described at codon alpha32, a position involved in alpha1/beta1 interaction. The possibility of a contribution of this mutation to the nephropatic state of the proband is discussed.

Evaluation of the living kidney donor: current perspectives

Living kidney donation is increasing because of prolonged waiting times on the transplant list, as well as improved outcomes for recipients. In 2001, the number of living donors surpassed the number of deceased donors; this trend likely will continue with ever-increasing margins. Because of this increase, as well as changes in our society's health, it is time to re-review the guidelines for selecting living kidney donors established by Kasiske et al in 1995. A conference will be held this year to review updated literature on medical conditions that impact on renal health. From this, new guidelines for the medical evaluation of living renal donors will be constructed. This review discusses information known to date on the outcomes of individuals undergoing unilateral nephrectomy, the impact of lifestyle on renal function in the setting of nephrectomy, and advancements in the detection of genetically transmitted renal diseases that impact on today's decisions on living donation.

Albuminuria in Afro-Caribbeans with Type 2 diabetes mellitus: is the sickle cell trait a risk factor?

AIMS

To determine the prevalence of albuminuria [raised albumin-creatinine ratio (ACR)] in an out-patient population of Afro-Caribbeans with Type 2 diabetes mellitus (DM) and to determine if the possession of the sickle cell trait (SCT) is a risk factor.

PATIENTS AND METHODS

The ACR in a morning urine sample was determined in each of 181 Afro-Caribbeans with Type 2 DM attending the out-patient clinic at King's Diabetes Centre of King's College Hospital, London. The subjects were genotyped for the SCT, Haemoglobin AS (HbAS).

RESULTS

Although a raised ACR was demonstrated more frequently in those with the SCT than in those without, with an odds ratio of 1.19, this was not statistically significant (P = 0.68).

CONCLUSIONS

In this study the possession of the SCT does not appear to play a significant role in the development of albuminuria. However, a larger study is needed to clarify its role as a risk factor for development of albuminuria in Afro-Caribbeans with Type 2 DM.

Microalbuminuria as a predictor of early glomerular injury in children with sickle cell disease

OBJECTIVE

A cross sectional study was carried out to determine the prevalence of microalbuminuria in the pediatric patients with sickle cell disease.

METHODS

The study was carried out on 64 pediatric patients aged less than 14 years with documented HbSS, HbAS and HbS beta thalassemia, Microalbuminuria was estimated using single radial immuno diffusion technique. Majority of the study subjects were of HbSS type. 38.5% had symptoms for > 2 years. 18.8% of the study population had significant microalbuminuria (19.2% of SS type and 18.8% of Hb AS types).

RESULT

Microalbuminuria excretion was significantly more in patients > 9 years of age as compared to young patients (p < 0.05). Mean serum creatinine levels did not show any significant difference in the various study groups.

CONCLUSION

Microalbuminuria estimation is a very important clinical marker of preclinical glomerular damage in patients with sickle cell disease. It estimation would help in the early detection of such patients and prompt initiation of therapy.

Renal complications of sickle cell disease: managing for optimal outcomes

A broad spectrum of renal changes is observed in patients with sickle cell anemia, and ideal therapeutic measures for the management of these alterations are still being studied. Affected patients have deficient urinary concentration and potassium excretion. Perhaps owing to a compensatory mechanism, the proximal tubules are in a condition of "hyperfunction", with increased sodium and phosphorus reabsorption and greater creatinine and uric acid secretion. Mild tubular acidosis may be present. No treatment has been reported for these tubular changes, except for care in the maintenance of hydration. The use of anti-inflammatory drugs is being studied in order to inhibit the prostaglandins involved in the process. Increased renal blood flow, glomerular filtration rate, and filtration fraction are frequent findings. Hematuria commonly occurs as a consequence of red blood cell sickling in the renal medulla, papillary necrosis, or even renal medullary carcinoma. Measures such as increased fluid ingestion, urine alkalinization and, if necessary, administration of epsilon-aminocaproic acid and certain invasive procedures have been proposed to treat hematuria. Nephropathy in patients with sickle cell anemia can be manifested by proteinuria and, more rarely, nephrotic syndrome. Drugs such as prednisone and cyclophosphamide are ineffective for the treatment of patients with nephrotic syndrome. Angiotensin converting enzyme inhibitors decrease proteinuria, but their long-term effect in preventing the progression of glomerular disease has not been established. Chronic renal failure, although infrequent, may be one of the manifestations of this disease. Hemodialysis and transplantation are satisfactory therapeutic options for patients with end-stage renal disease.

Renal pathology in hemizygous sickle cell mice

Transgenic mice have been developed that express exclusively human sickle cell beta hemoglobin and have major pathological features found in humans with sickle cell disease. These mice provide a unique opportunity to investigate the fundamental mechanisms of this disease and to design new strategies to correct the associated genetic defect(s). We found that in breeding males expressing only adult human alpha-globin and sickle beta-globin (homozygous SS mice) with females containing these transgenes plus one copy of the mouse beta-globin gene (hemizygous SS mice) greater than expected numbers of hemizygous offspring were produced than homozygous mice (carrying no mouse beta-globin gene). These hemizygous mice, expressing the human alpha and sickle beta(s) transgenes in combination with mouse beta+/-, were used for our preliminary studies of their renal pathology. No kidney lesions were found in the control (129/Sv) mice, whereas about 50% of the hemizygous SS mice showed mild-to-severe kidney lesions, including glomerulonephritis, cystic atypical hyperplastic tubules, and general nephropathy. Kidneys of some hemizygous mice were normal or showed minimal nephropathy, yet those of the susceptible phenotype developed a mild-to-more-severe form of renal lesions. The tubular epithelium of kidneys of hemizygous mice of the more affected phenotype exhibited increased expression of inducible nitric oxide synthase with an increased 3-nitrotyrosine in close proximity. There was also a stronger immunostaining for vascular cell adhesion molecule-1 in the interstitial capillary cells as well as the tubular epithelial cells of the renal cortex, compared with normal control mice. The occurrence of a high incidence of renal abnormalities in our hemizygous SS mice suggests that these mice may provide a suitable model to study the pathogenesis of nephropathy resulting from altered blood flow and/or insufficient oxygen delivery.

The increasing prevalence of childhood sickle-cell disease in Ireland

BACKGROUND

Ireland has been relatively free of sickle-cell disease (SCD) and a care policy for the disease has not been established.

AIM

To determine the prevalence of childhood SCD in Ireland and to predict requirements for a comprehensive care and assessment programme.

METHODS

We retrospectively analysed the data of children with SCD presenting with sickle-cell crisis to one institution from January 1999 to April 2001. We also determined the nature and severity of the presenting haemoglobinopathy phenotype.

RESULTS

Ninety-two patients with haemoglobinopathy have been registered with the Paediatric Haematology Service. The majority are from Nigeria with a smaller number from Angola and the Congo. Sixty have sickle-cell trait, 23 SCD, four haemoglobin SC disease and two haemoglobin E (HbE). There have been 32 sickle-cell crises. The majority were haemolytic or splenic sequestration events with a smaller number of aplastic and vaso-occlusive events and one osteomyelitis.

CONCLUSION

The increasing number of children presenting with SCD as a result of the increasing refugee numbers requires a comprehensive care approach similar to that required for paediatric haemophilia to ensure optimum care.