Hydroxyurea is associated with lower prevalence of albuminuria in adults with sickle cell disease

The Risk of Kidney Injury in Patients With Sickle Cell Disease Treated With Ketorolac for Acute Pain

Ketorolac, a nonsteroidal anti-inflammatory drug, is used in combination with opioids to manage vaso-occlusive episodes (VOEs). The relationship between ketorolac use and kidney injury in pediatric patients with sickle cell disease (SCD) remains incompletely understood. We hypothesize that ketorolac is associated with acute kidney injury (AKI) in patients with SCD presenting with pain. All nonsurgical hospitalizations for VOEs treated with ketorolac between January 2014 and December 2022 were included. We used optimal matching methodology to identify control admissions (2:1 ratio) and used nonparametric tests to compare ketorolac administration between cases and controls. A total of 1319 encounters/253 patients were included in this study. AKI was noted in 1.1% of encounters and 5.5% of patients. Cases had significantly higher initial BUN than controls (9.0 vs. 6.0 mg/dL, P =0.012). In cases versus controls, there was significantly lower serum sodium (136.0 vs. 138.0 mmol/L, P =0.021). There was no association between ketorolac dose and development of AKI among children with SCD. Higher BUN and lower sodium in cases suggest that patients with AKI were more volume depleted on admission than controls. This highlights the need for strict assessment of fluid status upon admission for VOE.

Utilization and Perceptions of Hydroxyurea Therapy Among Adult Patients With Sickle Cell Disease in Al Ahsa, Saudi Arabia: A Cross-Sectional Study

BACKGROUND

Sickle cell disease (SCD) is a prevalent genetic disorder characterized by abnormal hemoglobin formation, resulting in severe complications. Hydroxyurea (HU) therapy has demonstrated efficacy in reducing SCD-related complications; however, its utilization patterns and patient perceptions remain underexplored, particularly in the Al Ahsa region of Saudi Arabia.

OBJECTIVE

This cross-sectional study aimed to assess the prevalence of HU usage among adult patients with SCD in Al Ahsa; identify the barriers to starting, maintaining, and discontinuing HU therapy; and evaluate the patient-reported outcomes associated with its use.

METHODS

Data were collected through face-to-face surveys and medical record reviews of adult SCD patients attending outpatient clinics in the Hereditary Blood Diseases Center of Al Ahsa, Saudi Arabia, between December 2023 and March 2024. Descriptive statistics and inferential analyses were performed using SPSS version 26.

RESULTS

A total of 345 adult SCD patients were included, with a mean age of 34.12 ± 11.1 years. Most participants were male (58.6%) and unmarried (55.4%). HU utilization was reported by 57.1% of the participants, with the highest adherence observed among older age groups (p = 0.001). Significant improvements in pain severity, hospitalization rates, and quality of life were reported among HU users (p < 0.001). Common barriers to HU use included concerns about side effects, lack of medical justification, and absence of medical advice.

CONCLUSION

This study provides valuable insights into the utilization and perceptions of HU therapy among adults with SCD in Al Ahsa, Saudi Arabia. Addressing identified barriers and promoting patient education are crucial for optimizing therapy adherence and improving clinical outcomes in this population.

Acute kidney injury is more common in hospitalised children with sickle cell anaemia in Africa

AIM

To document the prevalence, severity, hospital outcome and factors associated with acute kidney injury (AKI) in hospitalised children with sickle cell anaemia (SCA).

METHODS

In this prospective observational study involving children aged 0.5-17 years with SCA requiring hospitalisation, we used serum creatinine level at 0 and 48 h of hospitalisation to determine the presence of AKI.

RESULTS

The study involved 155 children with SCA aged 0.5-17 years with a median (interquartile range) age of 7.8 (4.3-11.0) years. Acute kidney injury occurred in 27 (17.4%) children with 33.3% reaching stage 3. Hepatomegaly (81.5% vs. 55.4%; p = 0.015), splenomegaly (33.3% vs. 10.9%; p = 0.003), dipstick proteinuria (22.2% vs. 5.4%; p = 0.004), and hematuria (29.6% vs. 3.1%; p = <0.001) were more common in those with AKI. In contrast, children with AKI had lower haematocrit (16.9% vs. 22.2%; p = <0.001) and serum bicarbonate (16.7 vs. 19.1 mmoL/L; p = 0.010) compared with those without AKI. Those with AKI had longer hospital stay (median [interquartile range]: 7 [4-12] days vs. 4 [3-6] days; p = 0.008).

CONCLUSION

AKI is common among hospitalised children with AKI and is associated with longer hospital stay.

Role of hydroxyurea therapy in the prevention of organ damage in sickle cell disease: a systematic review and meta-analysis

BACKGROUND

Hydroxyurea is an affordable drug that reduces vaso-occlusive crises and transfusion requirements in sickle cell disease. However, its effectiveness in preventing chronic organ damage is still unclear. This systematic review and meta-analysis aimed to evaluate the role of hydroxyurea in preventing organ morbidity.

METHOD

We included original articles published in English from 1st January 1990 to 31st January 2023, reporting hydroxyurea therapy and organ damage from PubMed, Google Scholar, Scopus, and CrossRef databases. A total of 45 studies with 4681 sickle cell disease patients were evaluated for organ damage.

RESULTS

Our analysis showed that hydroxyurea intervention significantly lowered transcranial Doppler and tricuspid regurgitant velocity, with a standardized mean difference of - 1.03 (- 1.49; - 0.58); I 2 = 96% and - 1.37 (CI - 2.31, - 0.42); I 2 = 94%, respectively. Moreover, the pooled estimate for albuminuria showed a beneficial effect post-hydroxyurea therapy by reducing the risk of albuminuria by 58% (risk ratio of 0.42 (0.28; 0.63); I 2 = 28%).

CONCLUSION

Our study found that a hydroxyurea dose above 20 mg/kg/day with a mean rise in HbF by 18.46% post-hydroxyurea therapy had a beneficial role in reducing transcranial doppler velocity, tricuspid regurgitant velocity, albuminuria, and splenic abnormality.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42023401187.

Clinicopathologic Study of Sickle Cell-associated Kidney Disease: A Nigerian Experience

BACKGROUND

Improvements in sickle cell disease (SCD) care have resulted in the survival of many patients into adulthood, although this is accompanied by the increased incidence of end-organ damage, including chronic kidney disease (CKD).

OBJECTIVES

This study assessed the prevalence, pattern and predictors of renal dysfunction in SCD patients and investigated the associated renal histopathologic changes.

METHODS

We evaluated 105 patients with SCD, for proteinuria, estimated glomerular filtration rate (eGFR), and tubular dysfunction. Renal biopsy was conducted on 22 patients who qualified. Data were analysed using SPSS package version 23.

RESULTS

Thirty-seven (35.2%) of the 105 patients had CKD, as defined by an eGFR of 60 ml/min/1.73 m2 and/or proteinuria. The fractional excretion of potassium (FEK) was elevated in all patients, whereas the fractional excretion of sodium (FENa) was elevated in 98.1%. Glomerular filtration rate was negatively correlated with irreversible percentage sickle cell count (r = -0.616, P = 0.0001), FEK (r = -0.448, P = 0.0001) and FENa (r = -0.336, P = 0.004). Age, irreversible percentage sickle cell count, haemoglobin levels and FENa were the major predictors of CKD. The histological pattern in the 22 patients who had biopsies was consistent with mesangioproliferative glomerulonephritis 11 (50%), minimal change disease 6 (27.3%), focal segmental glomerulosclerosis 3 (13.6%) and interstitial nephritis 2 (9.1%).

CONCLUSIONS

CKD was prevalent in SCD patients, and it was characterised by tubular dysfunction and mesangioproliferative glomerulonephritis. The main predictors of CKD were increased age, severity of vaso-occlusive crisis, worsening anaemia and tubular dysfunction.

Interventions for chronic kidney disease in people with sickle cell disease

BACKGROUND

Sickle cell disease (SCD), one of the commonest severe monogenic disorders, is caused by the inheritance of two abnormal haemoglobin (beta-globin) genes. SCD can cause severe pain, significant end-organ damage, pulmonary complications, and premature death. Kidney disease is a frequent and potentially severe complication in people with SCD. Chronic kidney disease (CKD) is defined as abnormalities of kidney structure or function present for more than three months. Sickle cell nephropathy refers to the spectrum of kidney complications in SCD. Glomerular damage is a cause of microalbuminuria and can develop at an early age in children with SCD, with increased prevalence in adulthood. In people with sickle cell nephropathy, outcomes are poor as a result of the progression to proteinuria and chronic kidney insufficiency. Up to 12% of people who develop sickle cell nephropathy will develop end-stage renal disease. This is an update of a review first published in 2017.

OBJECTIVES

To assess the effectiveness of any intervention for preventing or reducing kidney complications or chronic kidney disease in people with sickle cell disease. Possible interventions include red blood cell transfusions, hydroxyurea, and angiotensin-converting enzyme inhibitors (ACEIs), either alone or in combination.

SEARCH METHODS

We searched for relevant trials in the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, CENTRAL, MEDLINE, Embase, seven other databases, and two other trials registers.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing interventions to prevent or reduce kidney complications or CKD in people with SCD. We applied no restrictions related to outcomes examined, language, or publication status.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility, extracted data, assessed the risk of bias, and assessed the certainty of the evidence (GRADE).

MAIN RESULTS

We included three RCTs with 385 participants. We rated the certainty of the evidence as low to very low across different outcomes according to GRADE methodology, downgrading for risk of bias concerns, indirectness, and imprecision. Hydroxyurea versus placebo One RCT published in 2011 compared hydroxyurea to placebo in 193 children aged nine to 18 months. We are unsure if hydroxyurea compared to placebo reduces or prevents progression of kidney disease assessed by change in glomerular filtration rate (mean difference (MD) 0.58 mL/min /1.73 m2, 95% confidence interval (CI) -14.60 to 15.76; 142 participants; very low certainty). Hydroxyurea compared to placebo may improve the ability to concentrate urine (MD 42.23 mOsm/kg, 95% CI 12.14 to 72.32; 178 participants; low certainty), and may make little or no difference to SCD-related serious adverse events, including acute chest syndrome (risk ratio (RR) 0.39, 99% CI 0.13 to 1.16; 193 participants; low certainty), painful crisis (RR 0.68, 99% CI 0.45 to 1.02; 193 participants; low certainty); and hospitalisations (RR 0.83, 99% CI 0.68 to 1.01; 193 participants; low certainty). No deaths occurred in either trial arm and the RCT did not report quality of life. Angiotensin-converting enzyme inhibitors versus placebo One RCT published in 1998 compared an ACEI (captopril) to placebo in 22 adults with normal blood pressure and microalbuminuria. We are unsure if captopril compared to placebo reduces proteinuria (MD -49.00 mg/day, 95% CI -124.10 to 26.10; 22 participants; very low certainty). We are unsure if captopril reduces or prevents kidney disease as measured by creatinine clearance; the trial authors stated that creatinine clearance remained constant over six months in both groups, but provided no comparative data (very low certainty). The RCT did not report serious adverse events, all-cause mortality, or quality of life. Angiotensin-converting enzyme inhibitors versus vitamin C One RCT published in 2020 compared an ACEI (lisinopril) with vitamin C in 170 children aged one to 18 years with normal blood pressure and microalbuminuria. It reported no data we could analyse. We are unsure if lisinopril compared to vitamin C reduces proteinuria in this population: the large drop in microalbuminuria in both arms of the trial after only one month on treatment may have been due to an overestimation of microalbuminuria at baseline rather than a true effect. The RCT did not report serious adverse events, all-cause mortality, or quality of life.

AUTHORS' CONCLUSIONS

We are unsure if hydroxyurea improves glomerular filtration rate or reduces hyperfiltration in children aged nine to 18 months, but it may improve their ability to concentrate urine and may make little or no difference to the incidence of acute chest syndrome, painful crises, and hospitalisations. We are unsure if ACEI compared to placebo has any effect on preventing or reducing kidney complications in adults with normal blood pressure and microalbuminuria. We are unsure if ACEI compared to vitamin C has any effect on preventing or reducing kidney complications in children with normal blood pressure and microalbuminuria. No RCTs assessed red blood cell transfusions or any combined interventions to prevent or reduce kidney complications. Due to lack of evidence, we cannot comment on the management of children aged over 18 months or adults with any known genotype of SCD. We have identified a lack of adequately designed and powered studies, although we found four ongoing trials since the last version of this review. Only one ongoing trial addresses renal function as a primary outcome in the short term, but such interventions have long-term effects. Trials of hydroxyurea, ACEIs or red blood cell transfusion in older children and adults are urgently needed to determine any effect on prevention or reduction of kidney complications in people with SCD.

Emerging Therapies and Advances in Sickle Cell Disease with a Focus on Renal Manifestations

The underlying mechanisms of disease in sickle cell disease (SCD) contribute to a multifaceted nephropathy, commonly manifested as albuminuria. In severe SCD genotypes ( e.g. , Hemoglobin SS [HbSS]), albuminuria and CKD are major predictors of mortality in this population. Therefore, the monitoring and management of renal function is an intrinsic part of comprehensive care in SCD. Management of nephropathy in SCD can be accomplished with SCD-directed therapies and/or CKD-directed therapies. In the past 5 years, novel disease-modifying and palliative therapies have been approved in SCD to target aspects of the disease, such as anemia, inflammation, and vasculopathy. Along with conventional hydroxyurea and chronic transfusion, l -glutamine, crizanlizumab, and voxelotor have all been shown to mitigate some adverse effect of SCD, and their effect on nephropathy is being investigated. CKD-directed therapies such as renin-angiotensin-aldosterone system blockers have long been used in SCD nephropathy; however, more complete long-term studies on benefits are needed. Given the effect of renal disease on survival, further assessment of the mechanisms and efficacy of these SCD-directed or CKD-directed therapeutic agents is essential.

Hemolysis scavenger proteins and renal function marker in children with sickle cell disease at steady state: A cross-sectional study

Background and Aims

Hemolysis is a fundamental feature of sickle cell disease (SCD) contributing to the vaso-occlusive crisis of patients. The objectives of the study were to assess the link between hemolysis proteins and hematological parameters, and to validate cystatin C (CYS C) as a potent renal marker in diagnoising SCD.

Method

Here, a cross-sectional study carried out at the pediatric SCD clinic of the Komfo Anokye Teaching Hospital comprised 90 SCD children (HbSC, HbSF, and HbSS). ANOVA, t-test, and Spearman's rank correlation analysis were done. Elevated proteins levels were compared to standard values; alpha-1 microglobulin (A1M) (1.8-65 µg/L), CYS C (0.1-4.5 µmol/L), and haemopexin (HPX) (500-1500 µg/mL).

Results

The mean (standard deviation) age of participants was 9.830 (±0.3217) years, and 46% of them were males. From simple descriptive analysis, we observed that all but one patient had their HPX level below the reference range (<500 µg/mL). Here, A1M levels were shown to be within the appropriate reference range for all the patients except few patients. CYS C levels were also all within the required reference values. A Spearman's rank correlation test between full blood count and HPX generally suggested a weak but positive correlation; RBC (coef. = 0.2448; p = 0.0248), HGB (coef. = 0.2310; p = 0.030), hematocrit (coef. = 0.2509; p = 0.020), and platelet (coef. = 0.1545; p = 0.160). Mean corpuscular volume (coef. = -0.5645; p = 0.610) had a stronger but negative correlation with HPX. This study depicts a positive and stronger association between CYS C and HPX levels (coef. = 0.9996; p < 0.0001), validating the use of CYS C as a useful marker of renal function in persons with SCDs.

Conclusion

In the present study, we show that A1M levels were normal for most of the patients, hence CYS C levels are not alarming in this study. Further, there exists a correlation between hemolysis scavenger proteins and hematological parameters.

The pleiotropic effects of α-thalassemia on HbSS and HbSC sickle cell disease: Reduced erythrocyte cation co-transport activity, serum erythropoietin, and transfusion burden, do not translate into increased survival

α-Thalassemia is one of the most important genetic modulators of sickle cell disease (SCD). Both beneficial and detrimental effects have been described previously. We use a 12-year data set on a large cohort of patients with HbSS (n = 411) and HbSC (n = 146) to examine a wide range of these clinical and laboratory associations. Our novel findings are that α-thalassemia strongly reduces erythrocyte potassium chloride co-transporter (KCC) activity in both HbSS and HbSC (p = .035 and p = .00045 respectively), suggesting a novel mechanism through which α-thalassemia induces a milder phenotype by reducing red cell cation loss. This may be particularly important in HbSC where reduction in mean cell hemoglobin concentration is not seen and where KCC activity has previously been found to correlate with disease severity. Additionally, we show that α-thalassemia not only increases hemoglobin in patients with HbSS (p = .0009) but also reduces erythropoietin values (p = .0005), demonstrating a measurable response to improved tissue oxygenation. We confirm the reno-protective effect of α-thalassemia in patients with HbSS, with reduced proteinuria (p = .003) and demonstrate a novel association with increased serum sodium (p = .0004) and reduced serum potassium values (p = 5.74 × 10^-10 ). We found patients with α-thalassemia had a reduced annualized transfusion burden in both HbSS and HbSC, but α-thalassemia had no impact on annualized admission rates in either group. Finally, in a larger cohort, we report a median survival of 62 years in patients with HbSS (n = 899) and 80 years in those with HbSC (n = 240). α-thalassemia did not influence survival in HbSS, but a nonsignificant trend was seen in those with HbSC.

The nephropathy of sickle cell trait and sickle cell disease

Sickle cell syndromes, including sickle cell disease (SCD) and sickle cell trait, are associated with multiple kidney abnormalities. Young patients with SCD have elevated effective renal plasma flow and glomerular filtration rates, which decrease to normal ranges in young adulthood and subnormal levels with advancing age. The pathophysiology of SCD-related nephropathy is multifactorial - oxidative stress, hyperfiltration and glomerular hypertension are all contributing factors. Albuminuria, which is an early clinical manifestation of glomerular damage, is common in individuals with SCD. Kidney function declines more rapidly in individuals with SCD than in those with sickle cell trait or in healthy individuals. Multiple genetic modifiers, including APOL1, HMOX1, HBA1 and HBA2 variants are also implicated in the development and progression of SCD-related nephropathy. Chronic kidney disease and rapid decline in estimated glomerular filtration rate are associated with increased mortality in adults with SCD. Renin-angiotensin-aldosterone system inhibitors are the standard of care treatment for albuminuria in SCD, despite a lack of controlled studies demonstrating their long-term efficacy. Multiple studies of novel therapeutic agents are ongoing, and patients with SCD and kidney failure should be evaluated for kidney transplantation. Given the high prevalence and severe consequences of kidney disease, additional studies are needed to elucidate the pathophysiology, natural history and treatment of SCD-related nephropathy.

Advances in the diagnosis and treatment of sickle cell disease

Sickle cell disease (SCD), which affects approximately 100,000 individuals in the USA and more than 3 million worldwide, is caused by mutations in the βb globin gene that result in sickle hemoglobin production. Sickle hemoglobin polymerization leads to red blood cell sickling, chronic hemolysis and vaso-occlusion. Acute and chronic pain as well as end-organ damage occur throughout the lifespan of individuals living with SCD resulting in significant disease morbidity and a median life expectancy of 43 years in the USA. In this review, we discuss advances in the diagnosis and management of four major complications: acute and chronic pain, cardiopulmonary disease, central nervous system disease and kidney disease. We also discuss advances in disease-modifying and curative therapeutic options for SCD. The recent availability of L-glutamine, crizanlizumab and voxelotor provides an alternative or supplement to hydroxyurea, which remains the mainstay for disease-modifying therapy. Five-year event-free and overall survival rates remain high for individuals with SCD undergoing allogeneic hematopoietic stem cell transplant using matched sibling donors. However, newer approaches to graft-versus-host (GVHD) prophylaxis and the incorporation of post-transplant cyclophosphamide have improved engraftment rates, reduced GVHD and have allowed for alternative donors for individuals without an HLA-matched sibling. Despite progress in the field, additional longitudinal studies, clinical trials as well as dissemination and implementation studies are needed to optimize outcomes in SCD.

Clinical and genetic factors are associated with kidney complications in African children with sickle cell anaemia

Clinical and genetic factors have been reported as influencing the development of sickle cell nephropathy (SCN). However, such data remain limited in the paediatric population. In this cross-sectional study, we enrolled 361 sickle cell disease children from the Democratic Republic of Congo. Participants were genotyped for the beta (β)-globin gene, apolipoprotein L1 (APOL1) risk variants, and haem oxygenase-1 (HMOX1) GT-dinucleotide repeats. As markers of kidney damage, albuminuria, hyperfiltration and decreased estimated glomerular filtration with creatinine (eGFRcr) were measured. An association of independent clinical and genetic factors with these markers of kidney damage were assessed via regression analysis. Genetic sequencing confirmed sickle cell anaemia in 326 participants. Albuminuria, hyperfiltration and decreased eGFRcr were present in 65 (20%), 52 (16%) and 18 (5·5%) patients, respectively. Regression analysis revealed frequent blood transfusions, indirect bilirubin and male gender as clinical predictors of SCN. APOL1 high-risk genotype (G1/G1, G2/G2 and G1/G2) was significantly associated with albuminuria (P = 0·04) and hyperfiltration (P = 0·001). HMOX1 GT-dinucleotide long repeats were significantly associated with lower eGFRcr. The study revealed a high burden of kidney damage among Congolese children and provided evidence of the possible role of APOL1 and HMOX1 in making children more susceptible to kidney complications.

Predictors associated with sickle cell nephropathy: a systematic review

INTRODUCTION

Sickle cell anemia affects more than 30 million people worldwide. Chronic kidney disease develops in 40% of individuals. The death rate of patients with sickle nephropathy is still high, with little known predictors related to its development. To answer the question "What predictors are associated with the onset of chronic kidney disease in patients with sickle cell anemia?", this article seeks to contribute to a better understanding of sickle nephropathy, making possible a new look at the sickle cell anemia and its kidney complications.

METHODS

A systematic review was developed, using the PRISMA recommendation, for cohort studies on predictors related to the outcome of sickle nephropathy in patients with sickle cell anemia.

RESULTS

Initially 321 studies were identified in Pubmed, of which six were selected to compose this systematic review. Lower hemoglobin levels, increased ages and albuminuria were the most pointed predictors associated with chronic kidney disease.

CONCLUSION

The main predictors associated with the development of chronic kidney disease in individuals with sickle cell anemia were lower hemoglobin levels, increased ages, and albuminuria. New studies evaluating predictors for the development of chronic kidney disease in sickle cell anemia are needed to better understand its installation and prevent its progression.

Outcomes of Kidney Transplant Recipients with Sickle Cell Disease: An Analysis of the 2000-2019 UNOS/OPTN Database

Background: Lower patient survival has been observed in sickle cell disease (SCD) patients who go on to receive a kidney transplant. This study aimed to assess the post-transplant outcomes of SCD kidney transplant recipients in the contemporary era. Methods: We used the OPTN/UNOS database to identify first-time kidney transplant recipients from 2010 through 2019. We compared patient and allograft survival between recipients with SCD (n = 105) vs. all other diagnoses (non-SCD, n = 146,325) as the reported cause of end-stage kidney disease. We examined whether post-transplant outcomes improved among SCD in the recent era (2010–2019), compared to the early era (2000–2009). Results: After adjusting for differences in baseline characteristics, SCD was significantly associated with lower patient survival (HR 2.87; 95% CI 1.75–4.68) and death-censored graft survival (HR 1.98; 95% CI 1.30–3.01), compared to non-SCD recipients. The lower patient survival and death-censored graft survival in SCD recipients were consistently observed in comparison to outcomes of recipients with diabetes, glomerular disease, and hypertension as the cause of end-stage kidney disease. There was no significant difference in death censored graft survival (HR 0.99; 95% CI 0.51–1.73, p = 0.98) and patient survival (HR 0.93; 95% CI 0.50–1.74, p = 0.82) of SCD recipients in the recent versus early era. Conclusions: Patient and allograft survival in SCD kidney recipients were worse than recipients with other diagnoses. Overall SCD patient and allograft outcomes in the recent era did not improve from the early era. The findings of our study should not discourage kidney transplantation for ESKD patients with SCD due to a known survival benefit of transplantation compared with remaining on dialysis. Urgent future studies are needed to identify strategies to improve patient and allograft survival in SCD kidney recipients. In addition, it may be reasonable to assign risk adjustment for SCD patients.

Progression of albuminuria in patients with sickle cell anemia: a multicenter, longitudinal study

Sickle cell nephropathy results in chronic kidney disease (CKD), which is associated with significant morbidity and mortality in sickle cell anemia (SCA). Albuminuria is an early manifestation of sickle nephropathy; however, little is known about progression of albuminuria or its correlation with glomerular filtration rate (GFR) decline or CKD. We studied nephropathy progression in 303 SCA participants in a prospective, multicenter, longitudinal study. We collected steady-state urine and serum samples yearly and assessed albumin/creatinine ratio (ACR), estimated GFR (eGFR), and SCA and nephropathy biomarkers. Participants with albuminuria (ACR ≥30 mg/g) for ≥2 annual measurements were classified as having persistent albuminuria (PA). At baseline (mean age, 21 years; range, 2-64 years), 32% had albuminuria. In longitudinal multivariate analysis, ACR was associated with sex, anemia, older age, and higher bilirubin and kidney injury molecule-1 levels. Albuminuria increased with age by 3.5 mg/g per year (P < .0001). Of 175 participants with ≥3 annual samples, 81% with baseline albuminuria ≥100 mg/g developed PA. Decreased eGFR and adult CKD were associated with PA (P = .002 and P = .02, respectively), but not with baseline albuminuria. Rate of eGFR decline was steeper among adults (but not children) with albuminuria, compared with those without (P = .02). Participants with PA were more likely to have rapid eGFR decline compared with those without (P = .03). In this longitudinal study, albuminuria progressed with age, and adults with albuminuria had worse eGFR decline than those without. Albuminuria ≥100 mg/g predicted PA, which was associated with rapid eGFR decline and CKD development in adults with SCA. This trial was registered at www.clinicaltrials.gov as #NCT02239016.

Outcomes following kidney transplantation in patients with sickle cell disease: The impact of automated exchange blood transfusion

There are over 12,000 people with sickle cell disease (SCD) in the UK, and 4-12% of patients who develop Sickle Cell Nephropathy (SCN) progress to End Stage Renal Disease (ESRD). Renal transplantation offers the best outcomes for these patients with but their access to transplantation is often limited. Regular automated exchange blood transfusions (EBT) reduce the complications of SCD and may improve outcomes. However, concerns over alloimmunisation limit its widespread implementation. In this retrospective multicenter study, data were collected on 34 SCD patients who received a kidney transplant across 6 London Hospitals between 1997 and 2017. 20/34 patients were on an EBT program, pre or post renal transplantation. Overall patient and graft survival were inferior to contemporaneous UK data in the ESRD population as a whole, a finding which is well-recognised. However, patient survival (CI 95%, p = 0.0032), graft survival and graft function were superior at all time-points in those who received EBT versus those who did not. 4/20 patients (20%) on EBT developed de novo donor specific antibodies (DSAs). 3/14 patients (21%) not on EBT developed de novo DSAs. The incidence of rejection in those on EBT was 5/18 (28%), as compared with 7/13 (54%) not on EBT. In conclusion, our data, while limited by an inevitably small sample size and differences in the date of transplantation, do suggest that long-term automated EBT post renal transplant is effective and safe, with improvement in graft and patient outcomes and no increase in antibody formation or graft rejection.

Computer Algorithm-Based Hydroxyurea Dosing Facilitates Titration to Maximum Tolerated Dose in Sickle Cell Anemia

Adults with sickle cell disease (SCD) experience acute and chronic complications and die prematurely. When taken at maximum tolerated dose (MTD), hydroxyurea prolongs survival; however, it has not consistently reversed organ dysfunction. Patients also frequently do not take hydroxyurea, at least in part because of physician discomfort with prescribing hydroxyurea. We sought to develop a computer program that could easily titrate hydroxyurea to MTD. This was a single-arm, open-label pilot study. Fifteen patients with homozygous SCD were enrolled in the protocol, and 10 patients were followed at baseline and then for 1 year after hydroxyurea initiation or dose titration. Fetal hemoglobin significantly increased in all 10 patients from 8.3% to 25.1% (P < .001). Nine patients were titrated to MTD in an average of 7.9 months, and the tenth patient's hydroxyurea dose was increased to 33 mg/kg/day. Computer program dosing recommendations were the same as manual dosing decisions made using the same algorithm for all patients and at all times. We also evaluated markers of cardiopulmonary, liver and renal damage. Although cardiopulmonary function did not significantly improve, direct bilirubin and alanine aminotransferase levels significantly decreased (P < .001 and P < .01, respectively). Last, although kidney function did not improve, degree of proteinuria was significantly reduced (P < .05). We have developed a computer program that reliably titrates hydroxyurea to MTD. A larger study is indicated to test the program either as a computer program or a downloadable application.

Non-invasive urinary biomarkers of renal function in sickle cell disease: an overview

Sickle cell disease (SCD) is a hereditary condition characterized by homozygosis of the hemoglobin S (HbS) gene. Marked morbimortality is observed due to chronic hemolysis, endothelial injury, and episodes of vaso-occlusion, which leads to multi-organ damage. Renal impairment is common and may have different presentations, such as deficiency in urinary acidification or concentration, glomerulopathies, proteinuria, and hematuria, frequently resulting in end-stage renal disease (ESRD). Novel biomarkers of renal function, such as kidney injury molecule 1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) and monocyte chemoattractant protein 1 (MCP-1) are being studied in order to enable early diagnosis of kidney damage in SCD.

Kidney biopsy findings in children with sickle cell disease: a Midwest Pediatric Nephrology Consortium study

BACKGROUND

Renal damage is a progressive complication of sickle cell disease (SCD). Microalbuminuria is common in children with SCD, while a smaller number of children have more severe renal manifestations necessitating kidney biopsy. There is limited information on renal biopsy findings in children with SCD and subsequent management and outcome.

METHODS

This is a multicenter retrospective analysis of renal biopsy findings and clinical outcomes in children and adolescents with SCD. We included children and adolescents (age ≤ 20 years) with SCD who had a kidney biopsy performed at a pediatric nephrology unit. The clinical indication for biopsy, biopsy findings, subsequent treatments, and outcomes were analyzed.

RESULTS

Thirty-six SCD patients (ages 4-19 years) were identified from 14 centers with a median follow-up of 2.6 years (0.4-10.4 years). The indications for biopsy were proteinuria (92%) and elevated creatinine (30%). All biopsies had abnormal findings, including mesangial hypercellularity (75%), focal segmental glomerulosclerosis (30%), membranoproliferative glomerulonephritis (16%), and thrombotic microangiopathy (2%). There was increased use of hydroxyurea, angiotensin-converting-enzyme inhibitors, and angiotensin receptor blockers following renal biopsy. At last follow-up, 3 patients were deceased, 2 developed insulin-dependent diabetes mellitus, 6 initiated chronic hemodialysis, 1 received a bone marrow transplant, and 1 received a kidney transplant.

CONCLUSIONS

Renal biopsies, while not commonly performed in children with SCD, were universally abnormal. Outcomes were poor in this cohort of patients despite a variety of post-biopsy interventions. Effective early intervention to prevent chronic kidney disease (CKD) is needed to reduce morbidity and mortality in children with SCD.

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.

A Growing Population of Older Adults with Sickle Cell Disease

In countries with organized access to health care, survival of patients with sickle cell disease (SCD) has greatly improved, shifting the burden of care from a pediatrician to an internal medicine physician. As a consequence, cumulative disease complications related to chronic vasculopathy are becoming more apparent, adding to organ dysfunction from physiologic aging. The time has come for us to reevaluate the approach to managing the older adult with SCD by putting a greater emphasis on geriatric conditions while proactively considering curative options once previously offered only to younger patients, with comprehensive annual assessments and joint clinics with relevant specialists.

Hydroxyurea alters hematological, biochemical and inflammatory biomarkers in Brazilian children with SCA: Investigating associations with βS haplotype and α-thalassemia

This study investigated the effects of hydroxyurea (HU) on hematological, biochemical and inflammatory parameters in children with sickle cell anemia (SCA) in association with βS haplotype and α-thalassemia. We included 22 children with SCA who were followed for an average of 14.5 months. Laboratory parameters were assessed by electronic methods, and molecular analysis was investigated by PCR-RFLP and allele-specific PCR. Results showed significant increases in hemoglobin, HbF, hematocrit, MCV, MCH, glucose, HDL-C and albumin levels, as well as significant decreases in MCHC and AST levels, WBC, neutrophils, eosinophils, lymphocytes and reticulocytes, in children during HU therapy. HbF levels were positively correlated with hemoglobin, hematocrit, MCV and total protein, yet negatively correlated with MCHC, RDW, AAT and AST during HU therapy (p<0.05). Children who carried the Central African Republic haplotype, in response to HU therapy, presented significant increases in hemoglobin, hematocrit, triglycerides and uric acid levels, as well as significant decreases in MCHC, AST and direct bilirubin levels, WBC, neutrophils, eosinophils, lymphocytes and reticulocytes. Those with the Benin haplotype presented increases in HbF and albumin levels, and a reduction in platelet counts (p<0.05). Children with α-thalassemia presented decreased ALT during HU use, while those without this deletion presented increases in hemoglobin, hematocrit, MCV, MCH, HDL-C and albumin, as well as decreases in MCHC, neutrophils, lymphocytes, reticulocytes and AST (p<0.05). Hence, regardless of its use in association with βS haplotypes or α-thalassemia, HU seems to be linked to alterations in hemolytic, inflammatory, hepatic, lipid and glycemic profiles.

Sickle cell disease: Clinical presentation and management of a global health challenge

Sickle cell disease is an autosomal recessive, multisystem disorder, characterised by chronic haemolytic anaemia, painful episodes of vaso-occlusion, progressive organ failure and a reduced life expectancy. Sickle cell disease is the most common monogenetic disease, with millions affected worldwide. In well-resourced countries, comprehensive care programs have increased life expectancy of sickle cell disease patients, with almost all infants surviving into adulthood. Therapeutic options for sickle cell disease patients are however, still scarce. Predictors of sickle cell disease severity and a better understanding of pathophysiology and (epi)genetic modifiers are warranted and could lead to more precise management and treatment. This review provides an extensive summary of the pathophysiology and management of sickle cell disease and encompasses the characteristics, complications and current and future treatment options of the disease.

Progressive Decline in Estimated GFR in Patients With Sickle Cell Disease: An Observational Cohort Study

RATIONALE & OBJECTIVE

Progression of chronic kidney disease (CKD) in sickle cell disease (SCD) and its risk factors remain poorly defined. We identified characteristics associated with CKD as well as decline in estimated glomerular filtration rate (eGFR) and presence of proteinuria over time in adults with SCD.

STUDY DESIGN

Retrospective observational study.

SETTING & PARTICIPANTS

Patients with SCD 18 years or older in a single center from 2004 to 2013.

PREDICTORS

Baseline clinical and laboratory measures, comorbid conditions, SCD-related complications, relevant treatments, and severity of genotypes defined as severe (homozygous SCD [HbSS]/sickle-β⁰-thalassemia [HbSβ⁰]) or mild (hemoglobin SC disease [HbSC]/sickle-β⁺-thalassemia [HbSβ⁺]-thalassemia).

OUTCOMES

Presence at baseline of CKD, defined here as eGFR<90mL/min/1.73m² or proteinuria (≥1+) on urinalysis or current kidney transplant or dialysis therapy; change in eGFR; and presence of proteinuria over time.

ANALYTICAL APPROACH

Logistic regression for baseline CKD. Linear mixed-effects model for eGFR decline and generalized linear mixed-effects model for proteinuria during the study period evaluating for interaction with time. Stratified by genotype severity.

RESULTS

Among 427 patients, 331 had 2 or more measurements of creatinine. During a median follow-up of 4.01 (interquartile range, 1.66-7.19) years, annual eGFR decline was 2.05mL/min/1.73m² for severe genotypes (P<0.001) and 1.16mL/min/1.73m² (P=0.02) for mild genotypes. At baseline, 21.4% of patients with severe genotypes had CKD versus 17.2% of those with mild genotypes. For severe genotypes, angiotensin-converting enzyme-inhibitor/angiotensin receptor blocker use (OR, 6.10; 95% CI, 2.03-18.29; P=0.001) and avascular necrosis (OR, 0.40; 95% CI, 0.16-0.97; P=0.04) were associated with baseline CKD. Among those with mild genotypes, higher hemoglobin level was associated with lower probability of CKD (OR per 1-g/dL greater hemoglobin level, 0.63; 95% CI, 0.43-0.93; P=0.02). Rate of eGFR decline was inversely related to hemoglobin level (β = 0.46 [SE, 0.23]; P=0.04) within the severe genotype subgroup. No factors were identified to be associated with proteinuria over time.

LIMITATIONS

Retrospective observational study, limited direct measures of albuminuria.

CONCLUSIONS

Patients with SCD exhibit rapid decline in eGFR over time. Decline in eGFR is associated with markers of disease severity and associated comorbid conditions.

Combined hydroxyurea and ETA receptor blockade reduces renal injury in the humanized sickle cell mouse

AIM

The objective of this study is to determine if ambrisentan (ET_A selective antagonist) and hydroxyurea (HU) treatment has a synergistic effect on renal injury in sickle cell nephropathy when compared to HU treatment alone. The premise of the study is based on recent studies showing that endothelin-1 (ET-1) contributes to the pathophysiology of nephropathy in sickle cell disease (SCD) and that ET_A receptor blockade improves renal function and protects against renal injury. Hydroxyurea (HU) is commonly prescribed for the treatment of SCD and has been shown to reduce renal injury in patients with SCD.

METHODS

Male 12-week-old humanized sickle mice (HbSS) and their genetic controls (HbAA) were treated with vehicle, HU, ambrisentan, or HU with ambrisentan for 2 weeks and renal structure and function were assessed.

RESULTS

Vehicle treated HbSS mice exhibited significant proteinuria compared to vehicle treated HbAA mice. HbSS mice also displayed significantly elevated plasma ET-1 concentrations and decreased urine osmolality compared to HbAA controls. Proteinuria was significantly lower in both HU and ambrisentan treated animals compared to vehicle treated HbSS mice; however, there was no additional improvement in HbSS mice treated with combined ambrisentan and HU. The combination of HU and ambrisentan resulted in significantly lower KIM-1 excretion, glomerular injury, and interstitial inflammation than HU alone.

CONCLUSION

These findings indicate that HU and ET_A receptor blockade produce similar reductions in renal injury in the humanized sickle mouse suggesting that both treatments may converge on the same mechanistic pathway.

Effect of renin-angiotensin-aldosterone system blocking agents on progression of glomerulopathy in sickle cell disease

Although renin-angiotensin-aldosterone system (RAAS) blocking agents decrease albuminuria in short-term studies, there is no evidence confirming their long-term efficacy in sickle cell disease (SCD). In a single-centre, retrospective study, we evaluated the long-term effect of RAAS blocking agents on proteinuria and declining estimated glomerular filtration rates (eGFR). Eighty-six patients on RAAS blocking agents for proteinuria, followed for a median of 2·28 years, were compared with 68 patients with proteinuria followed for 2·24 years who were not receiving such treatment. The log odds of proteinuria decreased over time in patients on RAAS blocking agents (β: -0·23, P = 0·03) and in the non-treatment group (β: -0·54, P < 0·0001), but was not statistically different between both groups (β: 0·31, P = 0·063). The eGFR declined over time in patients on RAAS blocking agents (β: -2·78, P < 0·0001) and in those not on such treatment (β: -4·7, P < 0·0001), and was statistically different between both groups (β: 1·9, P = 0·0002). Baseline eGFR was associated with mortality (Hazard rato: 0·97, P < 0·0001), but RAAS blocking agents had no significant effect on mortality. These data suggest that RAAS blockade may slow the loss of kidney function in SCD.

How I treat the older adult with sickle cell disease

With increasing survival, cumulative complications of sickle cell disease (SCD), which develop insidiously over time, are becoming more apparent and common in older patients, particularly those in their fifth decade and beyond. The older patient is also more likely to develop other age-related nonsickle conditions that interact and add to the disease morbidity. A common misconception is that any symptom in a SCD patient is attributable to their SCD and this may lead to delays in diagnosis and appropriate intervention. We recommend regular comprehensive reviews and monitoring for early signs of organ damage and a low threshold for the use of hydroxyurea and blood transfusions as preventative measures for end-organ disease. Treatable comorbidities and acute deterioration should be managed aggressively. Although the primary goal in management of the older adult with SCD is improving anemia and minimizing organ damage, the time has come for us to be more proactive in considering curative therapies previously offered to the younger patient. Curative or experimental interventions should be discussed early, before complications render the patients ineligible for these treatments.

Nephrin as a biomarker of sickle cell glomerulopathy in Malawi

BACKGROUND

Glomerulopathy is an increasingly identified complication in young patients with sickle cell disease (SCD). Hyperfiltration and albuminuria followed by declining glomerular filtration rates and eventual end-stage renal disease (ESRD) is assumed to be the typical progression of glomerular disease. There are only a few reported biomarkers to identify early-stage renal disease in SCD.

PROCEDURES

We detail the renal profile of 101 children with SCD in Malawi and propose a novel urinary biomarker for the identification of early renal disease.

RESULTS

Among children with sickle cell anemia, 24.8% had a urine albumin-creatinine ratio of 30 mg/g or above. In univariate analysis, only patients with higher urinary nephrin, a urinary marker of glomerular injury, had significantly greater odds of having albuminuria. In multivariable analysis, nephrin remained significantly associated with albuminuria. A nephrin-creatinine ratio (NCR) cut-point of 622 ng/mg, the 50^th percentile, was associated with a 45.8 times greater odds of having albuminuria in children with nephrinuria above this value. Further analysis revealed this urinary NCR cut-point to have 96% sensitivity, 64% specificity, 47% positive predictive value, and 98% negative predictive value for the presence of albuminuria.

CONCLUSIONS

These data suggest that a substantial number of children with SCD in Malawi have renal disease and could be at risk for worsening nephropathy and ESRD as they age. Our data suggest that urinary nephrin could be utilized as an early marker of glomerular disease in SCD.

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.

[Screening for nephropathy in major sickle cell syndromes in patients monitored at the National Reference Center for Sickle Cell Disease in Niamey, Niger]

BACKGROUND

Sickle cell anemia is the most common hereditary hemopathy in the world. It is a disease that attacks all the systems of the organism. The kidneys are among the most sensitive organs of this disease. The main objective of this study is to detect sickle cell nephropathy in patients followed at the National Reference Center for Sickle Cell Disease in Niamey.

METHODS

It is a prospective study carried out over a period of one year (January to December 2016). It included patients aged at least two years who had not had a vaso-occlusive crisis (VOC) for 2 months and not transfused for at least 3 months. A questionnaire was sent to each patient to collect demographic, clinical and biological information. Each patient provided a fresh blood and urine sample to assess biological parameters. We used Schwartz's formula in children and CKD-EPI in adults to assess glomerular filtration rate. The Pearson correlation coefficient (r) was used to assess the relationship between the different parameters under study. The threshold for statistical significance was set at 0.05.

RESULTS

Two hundred and eighty participants were included in the study. Adolescents (≤17years) were 226 (80.71%) and adults were 54 (19.29%). The mean age of the patients was 11.94±4.70years. It was lower in SS subjects and higher in SC. The SS form accounted for 87.5% of the three sickle cell disease phenotypes encountered. The age group 6-15years was the most predominant (42.86%). The mean baseline hemoglobin in the sample was 7.59±1.15g/dL ; (6.8 ±0.9d/dL) in SS patients and higher (10.5±2.1g/dL) in SC patients. The average glomerular filtration rate was 201.04mL/min/1.73m². Glomerular hyperfiltration was found in 90% of the sample, it was lower (77.6%) in Sβ thalassemia patients (P=0.000). In young subjects hyperfiltration was present in 84.95% against it was observed in only 29.63% of adults. Proteinuria was positive in 20% of patients. Positive proteinuria was found in 6.20% pediatric cases. The SC form was the most affected and in 74.6% of the patients it was positive at 1+. Chronic kidney disease (CKD) was found in 10% of the participants, of whom 75% were of the SS phenotype. Sβ thalassemia subjects had no CKD. The male sex was predominant in subjects with CKD (P=0.000). Patients over 15 years of age accounted for more than 95% of patients in both forms of the disease (P=0.0001).

CONCLUSION

The SS form of the disease, recurrent vaso-occlusive crisis, male sex and advanced age were the main precipitating factors in the development of renal function disorders.

Early Markers of Sickle Nephropathy in Children With Sickle Cell Anemia Are Associated With Red Cell Cation Transport Activity

The early stages of sickle cell nephropathy (SCN) manifest in children with sickle cell anemia (SCA) as hyperfiltration and proteinuria. The physiological conditions of the renovascular system are among the most conducive to hemoglobin S polymerization in the body and will magnify small changes in red cell volume thus crucially modulating intracellular concentrations of hemoglobin S. This large cross-sectional study of children with sickle cell anemia measured glomerular filtration rates and microalbuminuria to report prevalence, clinical correlates and uniquely, association with key red cell cation transport mechanisms. One hundred and twelve patients (mean age 10.7 ± 4.1) were recruited. The prevalence of hyperfiltration and microalbuminuria was 98% and 15.1%, respectively. Glomerular filtration rates did not vary with age, but proteinuria became more prevalent with increasing age. Both features associated with markers of hemolysis, while elevated hemoglobin F was protective, but no association was seen with systolic or diastolic blood pressure. In multivariate analysis, both Gardos channel (β = 0.476, P < 0.001) and KCl co-transporter (KCC; β = -0.216, P = 0.009) activity, alongside age (β = 0.237, P = 0.004), remained independently predictive for microalbuminuria. Increased activity of Gardos channel and P_sickle positively associated with microalbuminuria, while increased KCC activity associated with a reduction in microalbuminuria. This study demonstrates a direct link between the abnormally active red cell cation transport systems in sickle cell disease and sickle organopathy. Small variations in the activity of these transport mechanisms predict for SCN and measurement of them may help identify those at risk, while pharmaceutical manipulation of these excessively active systems may ameliorate their risk.

Changes in urine albumin to creatinine ratio with the initiation of hydroxyurea therapy among children and adolescents with sickle cell disease

BACKGROUND

Renal damage is a progressive complication of sickle cell disease (SCD) that begins in childhood and may progress to renal failure and early mortality in 12% of adults with hemoglobin SS (HbSS) SCD. Early sickle nephropathy is characterized by hyperfiltration and microalbuminuria; therefore, urine albumin to creatinine ratio (ACR) is an effective screening tool for its detection.

PROCEDURE

This study investigated the effect of hydroxyurea (HU) therapy on urine ACR levels among children with SCD. A retrospective review was conducted to identify all patients with HbSS or HbSβ⁰ thalassemia of age 7-18 years who began HU therapy in 2011-2013; a control group of patients not on HU were matched by age and baseline hemoglobin. All urine ACR measurements ≤24 months prior to and ≥24 months after HU initiation were recorded.

RESULTS

There were 63 eligible patients on HU and 13 (25%) with albuminuria prior to HU initiation. Among those with baseline albuminuria, the median ACR was 96 mg/g prior to HU, 39 mg/g at 1 year (P = 0.02), and 25 mg/g at 2 years (P = 0.03). Albuminuria normalized in 37.5% (6/16) after 1 year and 61% (8/13) after 2 years of HU therapy. Among those without albuminuria prior to HU, 13% (6/47) developed albuminuria during HU therapy. Sixteen percent (13/80) of control patients had albuminuria in the beginning of study period, which normalized in 15% (two of 13) of patients at 1-year follow up.

CONCLUSION

Introduction of HU is associated with significant decreases in urine ACR in children with SCD and albuminuria.

The spectrum of sickle hemoglobin-related nephropathy: from sickle cell disease to sickle trait

INTRODUCTION

Renal dysfunction is among the most common complication of sickle cell disease (SCD), from hyposthenuria in children to progression to overt chronic kidney disease (CKD) in young adults. Emerging evidence now suggests that sickle hemoglobin-related nephropathy extends to individuals with sickle cell trait (SCT). Areas covered: This review will highlight the pathophysiology, epidemiology, and management recommendations for sickle hemoglobin-related nephropathy in both SCD and SCT. In addition, it will focus on the major demographic and genetic modifiers of renal disease in sickling hemoglobinopathies. Expert commentary: Studies have elucidated the course of renal disease in SCD; however, the scope and age of onset of renal dysfunction in SCT has yet to be determined. In SCD, several modifiers of renal disease - such as α-thalassemia, hemoglobin F, APOL1 and HMOX1 - have been described and provide an opportunity for a precision medicine approach to risk stratify patients who may benefit from early intervention. Extrapolating from this literature may also provide insight into the modifiers of renal disease in SCT. Further studies are needed to determine the optimal treatment for sickle hemoglobin-related nephropathy.

Prospective evaluation of chronic organ damage in adult sickle cell patients: A seven-year follow-up study

Organ damage in sickle cell disease (SCD) is a crucial determinant for disease severity and prognosis. In a previous study, we analyzed the prevalence of SCD-related organ damage and complications in adult sickle cell patients. We now describe a seven-year follow-up of this cohort.All patients from the primary analysis in 2006 (n = 104), were included for follow-up. Patients were screened for SCD-related organ damage and complications (microalbuminuria, renal failure, elevated tricuspid regurgitation flow velocity (TRV) (≥2.5 m/seconds), retinopathy, iron overload, cholelithiasis, avascular osteonecrosis, leg ulcers, acute chest syndrome (ACS), stroke, priapism and admissions for vaso-occlusive crises (VOC) biannually. Upon 7 years of follow-up, progression in the prevalence of avascular osteonecrosis (from 12.5% to 20.4%), renal failure (from 6.7% to 23.4%), retinopathy (from 39.7% to 53.8%) was observed in the whole group. In HbSS/HbSβ⁰ -thal patients also progression in microalbuminuria (from 34% to 45%) and elevated TRV (from 40% to 48%) was observed while hardly any progression in the prevalence of cholelithiasis, priapism, stroke or chronic ulcers was seen. The proportion of patients with at least one episode of ACS increased in the group of HbSS/HbSβ⁰ -thal patients from 32% to 49.1%. In conclusion, 62% of the sickle cell patients in this prospective cohort study developed a new SCD-related complication in a comprehensive care setting within 7 years of follow-up. Although the hospital admission rate for VOC remained stable, multiple forms of organ damage increased substantially. These observations underline the need for continued screening for organ damage in all adult patients with SCD.

Losartan therapy decreases albuminuria with stable glomerular filtration and permselectivity in sickle cell anemia

Sickle cell nephropathy begins with hyperfiltration and microalbuminuria and may progress to renal failure. The aim of this study was to determine the effects of losartan on glomerular function and albumin excretion in sickle cell anemia (SCA). Individuals with SCA on hydroxyurea with persistent albuminuria were enrolled in a 1-year study of losartan. Glomerular filtration rate (GFR) measured by iohexol clearance, albumin excretion rate (AER), and fractional clearance of dextran were assessed at baseline, short-term (1-2month), and long-term (≥12month) intervals. Twelve subjects (6 microalbuminuria, 6 macroalbuminuria) completed short-term studies; 8 completed long-term studies. Baseline GFR was 112ml/min/1.73m² (71-147ml/min/1.73m²). AER decreased significantly at the short-term (median decrease -134 mcg/min, p=0.0063). GFR was not significantly-different at short-term or long-term intervals. Dextran clearance improved for diameters smaller than albumin (<36Å) but not larger sizes. Losartan therapy for ≥1year in sickle nephropathy results in lower albumin excretion with stable GFR. Filtration of neutral molecules ≥36Å was not changed by losartan, suggesting that the effect of losartan is a mechanism other than alteration of glomerular filtration size-selectivity.

Sickle cell disease

Sickle cell disease is a common and life-threatening haematological disorder that affects millions of people worldwide. Abnormal sickle-shaped erythrocytes disrupt blood flow in small vessels, and this vaso-occlusion leads to distal tissue ischaemia and inflammation, with symptoms defining the acute painful sickle-cell crisis. Repeated sickling and ongoing haemolytic anaemia, even when subclinical, lead to parenchymal injury and chronic organ damage, causing substantial morbidity and early mortality. Currently available treatments are limited to transfusions and hydroxycarbamide, although stem cell transplantation might be a potentially curative therapy. Several new therapeutic options are in development, including gene therapy and gene editing. Recent advances include systematic universal screening for stroke risk, improved management of iron overload using oral chelators and non-invasive MRI measurements, and point-of-care diagnostic devices. Controversies include the role of haemolysis in sickle cell disease pathophysiology, optimal management of pregnancy, and strategies to prevent cerebrovascular disease.

Prevalence and determinants of microalbuminuria in children suffering from sickle cell anemia in steady state

Background

Sickle cell anemia (SCA) is considered a major risk factor for renal complications. The main goal of this study was to determine the frequency of macroalbuminuria and microalbuminuria in Congolese children <18 years of age suffering from Sickle cell anemia and to identify associated factors.

Methods

The cross-sectional study was completed in 150 hemoglobin-SS children (77 boys and 73 girls). Microalbuminuria was defined by a urine albumin:creatinine ratio of 30–299 mg/g.

Results

The mean age of this group was 8.8 ± 4.3 years (range 2–18). Microalbuminuria was found in 27 children (18%). In multivariate logistic regression, only age emerged as a determinant of microalbuminuria odds ratio 1.11 (95% confidence interval 1.00–1.22); P = 0.042].

Conclusions

In our series, only age was a major determinant of the occurrence of microalbuminuria. These results confirm the need for early screening of microalbuminuria in Congolese children suffering from Sickle cell anemia in a context where access to renal and bone marrow transplant is nonexistent.

Use of anti-inflammatory analgesics in sickle-cell disease

WHAT IS KNOWN AND OBJECTIVE

Non-steroidal anti-inflammatory drugs (NSAIDs) have been commonly used to treat pain in sickle-cell disease (SCD), but NSAID use is associated with renal, gastrointestinal and cardiovascular toxicities. Our objective was to evaluate the use of aspirin and non-aspirin NSAIDs in SCD.

COMMENT

Despite analgesic and anti-inflammatory benefits in SCD, non-aspirin NSAIDs are associated with renal, cardiovascular and gastrointestinal toxicities in this patient population. Aspirin may have less renal and cardiovascular toxicities. The different side effect profile of NSAIDs is related to the COX-1/COX-2 selectivity at their therapeutic doses. Individual risk factors and genetic biomarkers should be considered when selecting appropriate NSAIDs and their dose.

WHAT IS NEW AND CONCLUSION

NSAIDs have the potential to be an important component of pain regimens in SCD, but the use of NSAIDs should be individualized based on potential side effects and patient risk factors and the lowest effective dose should be prescribed with proper monitoring in patients with SCD.

Sickle cell disease and albuminuria: recent advances in our understanding of sickle cell nephropathy

Albuminuria is considered to be a relevant biomarker for the detection of early glomerular damage in patients with sickle cell disease (SCD). Improvements in our understanding of the pathophysiological processes and molecular mechanisms underlying albuminuria are required, because increasing numbers of patients with SCD are developing chronic kidney disease. The early recognition of sickle cell nephropathy (SCN) and studies of the natural course of this emerging renal disease are therefore crucial, together with identification of the associated clinical and biological risk factors, to make it possible to initiate kidney-protective therapy at early stages of renal impairment. The pathophysiological process underlying SCN remains hypothetical, but chronic haemolysis-related endothelial dysfunction and the relative renal hypoxia triggered by repeated vaso-occlusive crises have been identified as two potential key factors. The optimal preventive and curative management of albuminuria in the context of SCD is yet to be established, but recent studies have suggested that hydroxyurea therapy, the cornerstone of SCD treatment, could play a key role in reducing albuminuria. The place of conventional kidney-protecting measures, such as renin–angiotensin system inhibitors, in the treatment of SCD patients also remains to be determined.

Sickle cell disease in the older adult

Sickle cell disease (SCD) is an inherited haemoglobin disorder, associated with recurrent painful episodes, ongoing haemolytic anaemia and progressive multi-organ damage. Until the early 1990s, survival beyond the fourth decade for a patient with SCD was considered unusual and prompted case reports. Nowadays, in countries with developed health care systems, more than 90 percent of newborns with SCD survive into adulthood. Nevertheless, their life expectancy is still shortened by more than two decades compared to the general population. With an increasing life expectancy, SCD has now evolved into a debilitating disorder with substantial morbidity resulting from ongoing sickle cell vasculopathy and multi-organ damage. Limited data on health care issues of older adults with SCD poses multiple challenges to patients, their families and health care providers. In this review, we will address and discuss acute and chronic complications of SCD with a special focus on the older adult.

Albuminuria Is Associated with Endothelial Dysfunction and Elevated Plasma Endothelin-1 in Sickle Cell Anemia

Background

The pathogenesis of albuminuria in SCD remains incompletely understood. We evaluated the association of albuminuria with measures of endothelial function, and explored associations of both albuminuria and measures of endothelial function with selected biological variables (vascular endothelial growth factor [VEGF], endothelin-1 [ET-1], soluble fms-like tyrosine kinase-1 [sFLT-1], soluble vascular cell adhesion molecule-1 [soluble VCAM-1] and plasma hemoglobin).

Methods

Spot urine measurements for albumin-creatinine ratio (UACR) and 24-hour urine protein were obtained. Endothelial function was assessed using brachial artery ultrasound with measurements of flow-mediated dilation (FMD), nitroglycerin-mediated dilation (NTMD) and hyperemic velocity.

Results

Twenty three subjects with varying degrees of albuminuria were evaluated. UACR was significantly correlated with FMD (ρ = -0.45, p = 0.031). In univariate analysis, UACR was correlated with VEGF (ρ = -0.49; 95% CI: -0.75 –-0.1, p = 0.015), plasma hemoglobin (ρ = 0.50; 95% CI: 0.11–0.75, p = 0.013) and ET-1 (ρ = 0.40; 95% CI: -0.03–0.69, p = 0.06). Multivariable analysis showed significant associations of ET-1 (estimate: 455.1 [SE: 198.3], p = 0.02), VEGF (estimate: -1.1 [SE: 0.53], p = 0.04) and sFLT-1 (estimate: -1.14 [SE: 0.49], p = 0.02) with UACR. Only ET-1 (estimate: -8.03 [SE: 3.87], p = 0.04) was significantly associated with FMD in multivariable analyses. Finally, UACR was correlated with both 24-hour urine protein (ρ = 0.90, p < 0.0001) and urine aliquots for albumin-creatinine ratio obtained from the 24-hour urine collection (ρ = 0.97, p < 0.0001).

Conclusion

This study provides more definitive evidence for the association of albuminuria with endothelial dysfunction in SCD. Elevated circulating levels of ET-1 may contribute to SCD-related glomerulopathy by mediating endothelial dysfunction.

Renal Failure in Sickle Cell Disease: Prevalence, Predictors of Disease, Mortality and Effect on Length of Hospital Stay

Renal dysfunction in sickle cell disease is not only a chronic comorbidity but also a mortality risk factor. Though renal dysfunction starts early in life in sickle cell patients, the predictors that can identify sickle cell disease patients at risk of developing renal dysfunction is not known. We used the Truven Health MarketScan^® Medicaid Databases from 2007 to 2012. Incidence of new acute renal failure (ARF) and chronic kidney disease (CKD) was calculated in this cohort. There were 9481 patients with a diagnosis of sickle cell disease accounting for 64,201 hospital admissions, during the study period. Both ARF and CKD were associated with higher risk of inpatient mortality, longer duration of the hospital stay and expensive hospitalizations. The yearly incidence of new ARF in sickle cell disease patients was 1.4% and annual CKD incidence was 1.3%. The annual rate of new ARF and CKD in the control group was 0.4 and 0.6%, respectively. The most important predictors of new CKD were proteinuria, ARF and hypertension. Chronic kidney disease, hypertension and sickle cell crisis were the most important predictors of new ARF. The annual rate of incidences of ARF and CKD were 2- to 3-fold higher in sickle cell disease compared to the non sickle cell disease group. Besides the common risk factors for renal disease in the general population, it is imperative to monitor the sickle cell disease patients with more severe disease to prevent them from developing renal dysfunction.

Hydroxyurea for Treatment of Nephrotic Syndrome Associated With Polycythemia Vera

Myeloproliferative disorders are a rare cause of focal segmental glomerulosclerosis (FSGS), although the mechanism is unclear. Hydroxyurea is commonly used in these disorders for its cytoreductive properties; however, the effect of this treatment on proteinuria or kidney function remains unclear in cases of myeloproliferative disorder-associated FSGS. We describe the clinical course of a patient with polycythemia vera and nephrotic-range proteinuria, demonstrated to have FSGS on biopsy. The patient had a distant history of granulomatosis with polyangiitis (Wegener's), for which he routinely had his kidney function and proteinuria measured, allowing for early detection of nephrotic syndrome soon after being diagnosed with polycythemia vera. Treatment with hydroxyurea resulted in rapid improvement in proteinuria that correlated with a decrease in hematocrit. This response was replicated 2 additional times when the patient was taken off and then restarted on hydroxyurea therapy. He now maintains a steady dose of hydroxyurea with favorable kidney measures (proteinuria with <1g/d of protein excretion and serum creatinine of 1.27mg/dL [corresponding to estimated glomerular filtration rate of 56mL/min/1.73 m(2)]). This case suggests that early screening and treatment for myeloproliferative disorder-associated FSGS may lead to improved long-standing kidney function.

Six Months of Hydroxyurea Reduces Albuminuria in Patients with Sickle Cell Disease

The earliest symptom of glomerular injury in patients with sickle cell disease (SCD) is microalbuminuria. The effect of hydroxyurea (HU) on urine albumin-to-creatinine ratio (ACR) is unclear and should be determined, because increasing numbers of patients with SCD take this drug to improve red blood cell function. In this cohort study of 58 SS-homozygous adults with SCD who initiated HU therapy, we evaluated ACR changes and relationships of these changes with demographic, clinical, and biologic parameters at HU initiation (baseline) and 6 months later (follow-up). Between baseline and follow-up, ACR declined significantly for the entire population (3.0-1.7 mg/mmol; P<0.01), but this was primarily driven by the ACR reduction in the microalbuminuria subgroup (8.1-2.3 mg/mmol; P=0.03; n=23). According to bivariate analyses on 39 patients who did not receive a blood transfusion during the study period, the baseline to follow-up ACR decline was strongly associated with decreases in levels of hemolysis markers, percentage of dense red blood cells, and systolic BP. Bivariate analysis also revealed a close association between the ACR decrease and high baseline levels of hemolysis markers and percentage of dense red blood cells. These results show that urine ACR decreased significantly after 6 months of HU and confirm a close relationship between ACR and hemolysis evolution in patients with SCD.

2015 Clinical trials update in sickle cell anemia

Polymerization of HbS and cell sickling are the prime pathophysiological events in sickle cell disease (SCD). Over the last 30 years, a substantial understanding at the molecular level has been acquired on how a single amino acid change in the structure of the beta chain of hemoglobin leads to the explosive growth of the HbS polymer and the associated changes in red cell morphology. O2 tension and intracellular HbS concentration are the primary molecular drivers of this process, and are obvious targets for developing new therapies. However, polymerization and sickling are driving a complex network of associated cellular changes inside and outside of the erythrocyte, which become essential components of the inflammatory vasculopathy and result in a large range of potential acute and chronic organ damages. In these areas, a multitude of new targets for therapeutic developments have emerged, with several ongoing or planned new therapeutic interventions. This review outlines the key points of SCD pathophysiology as they relate to the development of new therapies, both at the pre-clinical and clinical levels.