The Role of Hyposthenuria in Enuresis Among Paediatric Patients With Sickle Cell Disease

Objectives

Enuresis is common among children with sickle cell disease (SCD). Many risk factors have been postulated, but its relation to hyposthenuria is debatable. This study aimed to determine the prevalence of enuresis in children with SCD in Basrah, Iraq, and to examine its relation with hyposthenuria.

Methods

A cross-sectional epidemiological study was performed on children with SCD who met the inclusion criteria at the Basrah Center for Hereditary Blood Diseases from December 2020 to May 2021. A questionnaire was used to collect relevant data. Blood samples were tested for haemoglobin genotype, certain blood indices and serum haemoglobin. Urine was tested for albumin and creatinine, and the specific gravity was measured using urine dipsticks. The relationships between enuresis and various sociodemographic and clinical variables were assessed. Binary logistic regression analysis was done to examine the independent risk factors of enuresis.

Results

A total of 161 out of 200 eligible children were included in this study (response rate: 80.5%). The majority of participants (60.9%) were males. The mean age of the participants was 10.9 ± 2.9 years. Enuresis was reported in 50 (31.1%) patients. The independent risk factors for enuresis included family history of enuresis (adjusted odds ratio [OR] = 5.94, 95% confidence interval [CI]: 2.54-13.89; P <0.001), hyposthenuria (OR = 3.76, 95% CI: 1.25-11.30; P = 0.018) and sleep disorders (OR = 2.90, 95% CI: 1.19-7.06; P = 0.019.

Conclusion

Enuresis is common among children with SCD in Basrah, Iraq. Hyposthenuria was significantly associated with enuresis. Family history of enuresis and sleep disorders were also found to be significantly related to enuresis.

Assessment of Renal Function Status in Steady-State Sickle Cell Anaemic Children Using Urine Human Neutrophil Gelatinase-Associated Lipocalin and Albumin:Creatinine Ratio

INTRODUCTION

Sickle cell anaemia is characterized by defective haemoglobin synthesis and is associated with both endocrine and metabolic alterations. The effects of this clinical condition on kidney function are multifactorial and often begin early in childhood. This study aims to assess renal function in children with sickle cell anaemia using urine albumin:creatinine ratio (ACR) and urine human neutrophil gelatinase-associated lipocalin (NGAL).

METHODS

This case-control study was conducted on 200 children aged 5-15 years in 2 tertiary hospitals in South West Nigeria: 150 were of haemoglobin S genotype and 50 were of haemoglobin A genotype. Serum urea, creatinine, urine albumin, and NGAL were assayed by known standard methods. eGFR, urine ACR, and urine NGAL/creatinine ratio (urine NCR) were calculated.

RESULTS

The weight, height, BMI, systolic blood pressure, plasma urea, plasma creatinine, and spot urine creatinine of the HbS genotype children were significantly lower compared to that of the HbA genotype children. The eGFR, spot urine albumin, and urine ACR were significantly higher in the HbS group compared to the HbA group. There was no significant difference in the spot urine NGAL and urine NCR between the 2 groups, though both were higher in the HbS group compared to the HbA group.

CONCLUSIONS

Kidney injury probably starts early in childhood in sickle cell individuals as indicated by the higher urine ACR detected in them. We infer that urine NGAL and uNCR are not sensitive markers of kidney disease especially in young sickle cell individuals possibly because of the hyperfiltration present at this age.

The increased neopterin content in turkish pediatric patients with sickle cell anemia

In the present study, the possible activation of cellular immunity in SCD patients was investigated. As immune activation parameters, neopterin concentrations and kynurenine/tryptophan ratio for tryptophan degradation in 35 pediatric patients with sickle cell disease (31 HbSS and 4 HbSß) were determined. Our results have shown that neopterin levels (both urinary and serum) are increased in pediatric patients with sickle cell disease. The increase in neopterin concentration was accompanied by significantly increased biopterin, kynurenine concentration and kynurenine/tryptophan ratio. The mechanism of immune activation and the effects of inflammatory mediators in sickle cell disease are poorly understood, especially in terms of cell-mediated immunity. Further in-vivo and in-vitro studies are required to illuminate the association between neopterin levels and neutrophil activation in sickle cell disease.

Urinary cross-linked carboxyterminal telopeptide, a bone resorption marker, decreases after vaso-occlusive crises in adults with sickle cell disease

People with sickle cell disease often report severe bone pain with repeated bouts of vaso-occlusive crises, but the extent of skeletal injury incurred during these painful episodes remain unclear. We sought to quantify bone degradation by comparing urinary concentrations of carboxyterminal cross-linked telopeptide of type I collagen (CTX-1), a well-described marker of bone resorption, in a prospective cohort of 52 adults with sickle cell disease enrolled in the Sickle Cell Pain Markers Study. We also questioned if changes in urinary CTX-1 concentrations correlated with changes in hemolysis and inflammatory markers measured both during and after resolution of a painful vaso-occlusive episode. Thirty-one of the 52 adults enrolled in the study had paired urine samples for CTX-1 analysis. Urinary CTX-1, corrected for urine creatinine, significantly decreased from a mean of 3.45 μg/mmol during vaso-occlusive crises to 2.62 μg/mmol at recovery (p = 0.01). Thus, increased bone loss appears to correlate with acute vaso-occlusive crises in sickle cell disease. Our finding that urinary CTX-1 can be used to probe bone degradation in sickle cell disease provides an important new tool for diagnosing and monitoring response to therapy for people with sickle cell-related bone loss.

Sickle cell disease up-regulates vasopressin, aquaporin 2, urea transporter A1, Na-K-Cl cotransporter 2, and epithelial Na channels in the mouse kidney medulla despite compromising urinary concentration ability

Sickle cell disease (SCD)-induced urinary concentration defect has been proposed as caused by impaired ability of the occluded vasa recta due to red blood cell sickling to serve as countercurrent exchangers and renal tubules to absorb water and solutes. However, the exact molecular mechanisms remain largely unknown. The present studies were undertaken to determine the effects of SCD on vasopressin, aquaporin2 (AQP2), urea transporter A1 (UTA1), Na-K-Cl co-transporter 2 (NKCC2), epithelial Na channels (ENaC), aquaporin1 (AQP1), nuclear factor of activated T cells 5 (NFAT5) and Src homology region-2 domain-containing phosphatase-1 (SHP-1), an important regulator of NFAT5, in the Berkeley SCD mouse kidney medulla. Under water repletion, SCD only induced a minor urinary concentration defect associated with increased urinary vasopressin level alone with the well-known effects of vasopressin: protein abundance of AQP2, UTA1 and ENaC-β and apical targeting of AQP2 as compared with non-SCD. SCD did not significantly affect AQP1 protein level. Water restriction had no further significant effect on SCD urinary vasopressin. NFAT5 is also critical to urinary concentration. Instead, water restriction-activated NFAT5 associated with inhibition of SHP-1 in the SCD mice. Yet, water restriction only elevated urinary osmolality by 28% in these mice as opposed to 104% in non-SCD mice despite similar degree increases of protein abundance of AQP2, NKCC2 and AQP2-S256-P. Water-restriction had no significant effect on protein abundance of ENaC or AQP1 in either strain. In conclusion, under water repletion SCD, only induces a minor defect in urinary concentration because of compensation from the up-regulated vasopressin system. However, under water restriction, SCD mice struggle to concentrate urine despite activating NFAT5. SCD-induced urinary concentration defect appears to be resulted from the poor blood flow in vasa recta rather than the renal tubules' ability to absorb water and solutes.

Five lessons learned about long-term pain management in adults with sickle cell disease

Chronic pain affects one-half of adults with sickle cell disease (SCD). Despite the prevalence of chronic pain, few studies have been performed to determine the best practices for this patient population. Although the pathophysiology of chronic pain in SCD may be different from other chronic pain syndromes, many of the guidelines outlined in the pain literature and elsewhere are applicable; some were consensus-adopted in the 2014 National Heart, Lung, and Blood Institute SCD Guidelines. Recommended practices, such as controlled substance agreements and monitoring of urine, may seem unnecessary or counterproductive to hematologists. After all, SCD is a severe pain disorder with a clear indication for opioids, and mistrust is already a major issue. The problem, however, is not with a particular disease but with the medicines, leading many US states to pass broad legislation in attempts to curb opioid misuse. These regulations and other key tenets of chronic pain management are not meant to deprive adults with SCD of appropriate therapies, and their implementation into hematology clinics should not affect patient-provider relationships. They simply encourage prudent prescribing practices and discourage misuse, and should be seen as an opportunity to more effectively manage our patient's pain in the safest manner possible. In line with guideline recommendations as well as newer legislation, we present five lessons learned. These lessons form the basis for our model to manage chronic pain in adults with SCD.

Cardiovascular complications in patients with sickle cell disease

Sickle cell disease (SCD) is an autosomal recessive disease in which homozygosity for a single point mutation in the gene encoding the β-globin chain produces hemoglobin S molecules that polymerize within the erythrocyte during deoxygenation; the result is sustained hemolytic anemia and vaso-occlusive events. As patients live to adulthood, the chronic impact of sustained hemolytic anemia and episodic vaso-occlusive episodes leads to progressive end-organ complications. This scenario culminates in the development of 1 or more major cardiovascular complications of SCD for which there are no approved or consensus therapies. These complications include elevated pulmonary artery systolic pressure, pulmonary hypertension, left ventricular diastolic heart disease, dysrhythmia, sudden death, and chronic kidney disease with associated proteinuria, microalbuminuria, and hemoglobinuria. In patients with advancing age, cardiopulmonary organ dysfunction and chronic kidney injury have significant effects on morbidity and premature mortality. Over the last 15 years, a number of tests have been validated in multiple replicate cohort studies that identify patients with SCD at the highest risk of experiencing pulmonary and systemic vasculopathy and death, providing for screening strategies tied to targeted, more aggressive diagnostic and therapeutic interventions.

Angiotensin-converting enzyme (ACE) inhibitors for proteinuria and microalbuminuria in people with sickle cell disease

BACKGROUND

Sickle cell disease is a group of disorders characterized by deformation of erythrocytes. Renal damage is a frequent complication in sickle cell disease as a result of long-standing anemia and disturbed circulation through the renal medullary capillaries. Due to the improvement in life expectancy of people with sickle cell disease, there has been a corresponding significant increase in the incidence of renal complications. Microalbuminuria and proteinuria are noted to be a strong predictor of subsequent renal failure. There is extensive experience and evidence with angiotensin-converting enzyme (ACE) inhibitors over many years in a variety of clinical situations for patients who do not have sickle cell disease, but their effect in people with this disease is unknown. It is common practice to administer ACE inhibitors for sickle nephropathy due to their renoprotective properties; however, little is known about their effectiveness and safety in this setting. This is an update of a Cochrane Review first published in 2013.

OBJECTIVES

To determine the effectiveness of ACE inhibitor administration in people with sickle cell disease for decreasing intraglomerular pressure, microalbuminuria and proteinuria and to to assess the safety of ACE inhibitors as pertains to their adverse effects.

SEARCH METHODS

The authors searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Hameoglobinopathies Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Date of the most recent search: 03 June 2015.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials of ACE inhibitors designed to reduce microalbuminuria and proteinuria in people with sickle cell disease compared to either placebo or standard treatment regimen.

DATA COLLECTION AND ANALYSIS

Three authors independently applied the inclusion criteria in order to select studies for inclusion in the review. Two authors assessed the risk of bias of studies and extracted data and the third author verified these assessments.

MAIN RESULTS

Five studies were identified through the searches, only one met our inclusion criteria. The included study randomized 22 participants (seven males and 15 females) having proteinuria or microalbuminuria with sickle cell disease and treated the participants for six months (median length of follow up of three months) with captopril or placebo. The overall quality of the outcomes reported was high, since most aspects that may contribute to bias were regarded to be of low risk, although allocation concealment was not reported. At six months, the study reported no significant difference in urinary albumin excretion between the captopril group and the placebo group, although the mean urinary albumin excretion in the captopril group was lower by a mean difference of -49.00 (95% confidence interval -124.10 to 26.10) compared to that of placebo. However, our analysis on the absolute change score showed significant changes between the two groups by a mean difference of -63.00 (95% confidence interval -93.78 to -32.22). At six months albumin excretion in the captopril group was noted to decrease from baseline by a mean of 45 ± 23 mg/day and the placebo group was noted to increase by 18 ± 45 mg/day. Serum creatinine and potassium levels were reported constant throughout the study. The potential for inducing hypotension should be highlighted; the study reported a decrease of 8 mmHg in systolic pressure and 5 mmHg in diastolic and mean blood pressure.

AUTHORS' CONCLUSIONS

There is not enough evidence to show that the administration of ACE inhibitors is associated with a reduction of microalbuminuria and proteinuria in people with sickle cell disease, although a potential for this was seen. More long-term studies involving multiple centers and larger cohorts using a randomized-controlled design are warranted, especially among the pediatric age group. Detailed reporting of each outcome measure is necessary to allow a clear cut interpretation in a systematic review. One of the difficulties encountered in this review was the lack of detailed data reported in the included study.

The glomerulopathy of sickle cell disease

Sickle cell disease (SCD) produces many structural and functional abnormalities in the kidney, including glomerular abnormalities. Albuminuria is the most common manifestation of glomerular damage, with a prevalence between 26 and 68% in adult patients. The pathophysiology of albuminuria in SCD is likely multifactorial, with contributions from hyperfiltration, glomerular hypertension, ischemia-reperfusion injury, oxidative stress, decreased nitric oxide (NO) bioavailability, and endothelial dysfunction. Although its natural history in SCD remains inadequately defined, albuminuria is associated with increased echocardiography-derived tricuspid regurgitant jet velocity, systemic blood pressure, and hypertension, as well as history of stroke, suggesting a shared vasculopathic pathophysiology. While most patients with albuminuria are treated with angiotensin converting enzyme inhibitors/angiotensin receptor blockers, there are no published long-term data on the efficacy of these agents. With the improved patient survival following kidney transplantation, SCD patients with end-stage renal disease should be considered for this treatment modality. Given the high prevalence of albuminuria and its association with multiple SCD-related clinical complications, additional studies are needed to answer several clinically important questions in a bid to adequately elucidate its pathophysiology, natural history, and treatment.

Angiotensin-converting enzyme (ACE) inhibitors for proteinuria and microalbuminuria in people with sickle cell disease

BACKGROUND

Sickle cell disease is a group of disorders characterized by deformation of erythrocytes. Renal damage is a frequent complication in sickle cell disease as a result of long-standing anemia and disturbed circulation through the renal medullary capillaries. Due to the improvement in life expectancy of people with sickle cell disease, there has been a corresponding significant increase in the incidence of renal complications. Microalbuminuria and proteinuria are noted to be a strong predictor of subsequent renal failure. There is extensive experience and evidence with angiotensin-converting enzyme (ACE) inhibitors over many years in a variety of clinical situations for patients who do not have sickle cell disease, but their effect in patients with this disease is unknown. It is common practice to administer ACE inhibitors for sickle nephropathy due to their renoprotective properties; however, little is known about their effectiveness and safety in this setting.

OBJECTIVES

To determine the effectiveness of ACE inhibitor administration in people with sickle cell disease for decreasing intraglomerular pressure, microalbuminuria and proteinuria and to to assess the safety of ACE inhibitors as pertains to their adverse effects.

SEARCH METHODS

The authors searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Hameoglobinopathies Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Date of the most recent search: 05 July 2012.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials of ACE inhibitors designed to reduce microalbuminuria and proteinuria in people with sickle cell disease compared to either placebo or standard treatment regimen.

DATA COLLECTION AND ANALYSIS

Three authors independently applied the inclusion criteria in order to select studies for inclusion in the review. Two authors assessed the risk of bias of studies and extracted data and the third author verified these assessments.

MAIN RESULTS

Five studies were identified through the searches, only one met our inclusion criteria. The included study randomized 22 participants (7 males and 15 females) having proteinuria or microalbuminuria with sickle cell disease and treated the participants for six months (median length of follow-up of three months) with captopril or placebo. At six months, the study reported no significant difference in urinary albumin excretion between the captopril group and the placebo group, although the mean urinary albumin excretion in the captopril group was lower by a mean difference of -49.00 (95% confidence interval -124.10 to 26.10) compared to that of placebo. However, our analysis on the absolute change score showed significant changes between the two groups by a mean difference of -63.00 (95% confidence interval -93.78 to -32.22). At six months albumin excretion in the captopril group was noted to decrease from baseline by a mean of 45 ± 23 mg/day and the placebo group was noted to increase by 18 ± 45 mg/day. Serum creatinine and potassium levels were reported constant throughout the study. The potential for inducing hypotension should be highlighted; the study reported a decrease of 8 mmHg in systolic pressure and 5 mmHg in diastolic and mean blood pressure.

AUTHORS' CONCLUSIONS

There is not enough evidence to show that the administration of ACE inhibitors is associated with a reduction of microalbuminuria and proteinuria in people with sickle cell disease, although a potential for this was seen. More long-term studies involving multiple centers and larger cohorts using a randomized-controlled design are warranted, especially among the pediatric age group. Detailed reporting of each outcome measure is necessary to allow a clear cut interpretation in a systematic review. One of the difficulties encountered in this review was the lack of detailed data reported in the included study.

Biomarkers for early detection of sickle nephropathy

Renal complications affect nearly 30-50% of adults with sickle cell anemia (SCA), causing significant morbidity and mortality. Standard renal function tests like serum creatinine and glomerular filtration rate become abnormal in this disease only when renal damage has become extensive and largely irreversible. Moreover, not all patients develop sickle nephropathy (SN). Therefore, noninvasive biomarkers that predict early onset of SN are necessary. We performed a cross-sectional analysis for nephropathy in 116 patients with sickle cell disease, analyzing urinary kidney injury molecule-1 (KIM-1), liver-type fatty acid binding protein (L-FABP), N-acetyl-b-D-glucosaminidase (NAG), neutrophil gelatinase-associated lipocalin (NGAL) and transforming growth factor-β1 (TGF-β), together with conventional renal biomarkers (urine albumin and osmolality, and serum creatinine and cystatin C estimated GFR) during routine clinic visits when patients were at steady-state/baseline. We observed a distinct biomarker pattern: KIM-1 and NAG emerged as biomarkers with a strong association with albuminuria. Surprisingly, and in contrast to other acute/chronic renal disorders, NGAL, L-FABP, and TGF-β levels did not show any relationship with albuminuria in patients with SCA. Our study identifies potential biomarkers for SN, and suggests longitudinal validation of these biomarkers for early detection of SN, so that therapeutic interventions can be applied before renal damage becomes irreversible.

Microalbuminuria in children with sickle cell anemia

Microalbuminuria (MA) is an early marker of various diseases affecting the renal system. Its relevance in children with sickle cell anemia (SCA), who are known to be prone to renal complications, has not been fully explored, particularly in the study locale. Besides, its occurrence in this group of patients remains under-reported in locations where the burden of SCA is enormous. To assess its prevalence in this cohort, 69 children with sickle cell anemia (in their steady state), aged 1-16 years, were consecutively enrolled and evaluated. The study, spanning from November 2006 to February 2007, was cross-sectional and descriptive. Employing a semiquantitative method, MA in an early morning spot urine sample was determined in each subject. Also evaluated were the anthropometry, blood pressure (BP) and packed cell volume. Prevalence of MA in the study subjects was 20.3%. Though not significant, prevalence of MA was more in females (25.9%) than in males (16.7%). Prevalence of MA increased with increasing age and was also significantly associated with weight (P = 0.033), but was independent of family history of hypertension. BP recordings, both systolic and diastolic, in the study subjects were within normal range. MA occurs significantly enough in children with SCA to warrant routine screening for it. Such a measure could assist in the early detection of ensuing renal complications and can pave way for improved management of a sickler who is particularly prone to such problems. In addition, interventional measures, known to retard rate of deterioration of kidney function due to prolonged proteinuria, could also be instituted early.

Protective role of hemoglobin and fetal hemoglobin in early kidney disease for children with sickle cell anemia

Patients with sickle cell anemia are at risk for organ damage including kidney disease. Microalbuminuria may be an early marker of disease progression. This retrospective review analyzed laboratory and clinical findings in children with sickle cell anemia according to the presence or absence of MA during well clinic sickle cell visits. Results were analyzed in sum as well as by therapeutic intervention (not on therapy,hydroxyurea therapy, or chronic transfusion therapy). Thirty two of 144(22%) children had MA, including 20 of 82 (24%) children not on a therapeutic intervention (chronic transfusion or hydroxyurea). In children not on therapy, low hemoglobin, low fetal hemoglobin and high lactate dehydrogenase were associated with MA. Frequency of positive screens for MA for the different treatment groups were: Hydroxyurea 13%; chronic transfusion 26% and children on no treatment 24%. However,the difference between the hydroxyurea group and the chronic transfusion or no treatment groups did not reach statistical significance.Increased hemoglobin and fetal hemoglobin may provide protection against kidney disease in sickle cell anemia and should be evaluated in a randomized, prospective clinical trial.

Urinary markers of bone resorption, pyridinoline and deoxypyridinoline, are increased in sickle cell patients with further increments during painful crisis

The painful crisis is the hallmark of sickle-cell disease (SCD). Bone resorption, as part of physiological bone turnover, results in release into the circulation with subsequent urinary excretion of the collagen cross-links pyridinoline (PYD) and deoxypyridinoline (DPD). Urinary PYD and DPD concentrations could reflect the extent of bone infarction during painful sickle-cell crisis. Urinary concentrations of PYD and DPD, adjusted for urine creatinine, were measured in sickle-cell patients (38 clinically asymptomatics and 27 during painful crisis) and healthy controls (n 5 25) using high-performance liquid chromatography(HPLC). PYD and DPD concentrations were higher in asymptomatic HbSS/HbSb0-thalassemia patients compared to controls (P <0.05) with further increments during painful crisis in both HbSS/HbSb0-thalassemia and HbSC/HbSb1-thalassemia patients (P < 0.05). In the asymptomatic HbSS/HbSb0-thalassemia patients, there was a statistically significant positive correlation between DPD and hemolytic rate.Based on urinary PYD and DPD concentrations, bone degradation is increased in asymptomatic sickle-cell patients, with further increments during painful crisis. Urinary PYD and DPD concentrations are potentially diagnostic and prognostic tools in SCD.

Urinary cysteinyl leukotriene E4 significantly increases during pain in children and adults with sickle cell disease

Baseline level of the cysteinyl leukotriene (CysLT), leukotriene E4 (LTE4), is associated with an increased pain rate in children and adults with sickle cell disease (SCD). To provide additional evidence for a role of CysLTs in the pathogenesis of vaso-occlusion, we tested the hypothesis that LTE4 levels will increase within an individual during painful episodes compared to baseline. In a cohort of 19 children and adults with SCD, median LTE4 levels increased from 82.36 pg/mg creatinine at baseline to 162.81 pg/mg creatinine during a painful episode (P < 0.001). These data further support a contribution of CysLTs to the process of vaso-occlusion.

Urinary cysteinyl leukotriene E(4) is associated with increased risk for pain and acute chest syndrome in adults with sickle cell disease

Leukotriene E(4) (LTE(4)) levels are associated with rate of pain episodes in children with sickle cell disease (SCD). Because complications of SCD manifest differently in adults than children, we examined a cohort of adults with SCD to determine the relationship between baseline LTE(4) and SCD-related morbidity. Baseline LTE(4) levels were associated with increased rates of pain and acute chest syndrome (ACS) episodes, when those with LTE(4) values in the highest tertile were compared with those in the lowest tertile (pain: risk ratio 7.1, 95% CI 1.8-27.5, P = 0.005; ACS: risk ratio 12.2, 95% CI 2.1-69.8, P = 0.005).

Elevated urinary leukotriene E4 levels are associated with hospitalization for pain in children with sickle cell disease

Cysteinyl leukotrienes (CsyLTs) are inflammatory mediators produced by white blood cells. Leukotriene LTE(4) is the stable metabolite of CsyLTs, which can be measured in urine. We tested two hypotheses among children with sickle cell disease (SCD): (1) baseline urinary LTE(4) levels are elevated in children with SCD when compared with controls; and (2) baseline LTE(4) levels are associated with an increased incidence rate of hospitalization for SCD-related pain. Baseline LTE(4) levels were measured in children with SCD (cases) and children without SCD matched for age and ethnicity (controls). Medical records of cases were reviewed to assess the frequency of hospitalization for pain within 3 years of study entry. LTE(4) levels were obtained in 71 cases and 22 controls. LTE(4) levels were higher in cases compared with controls (median LTE(4): 100 vs. 57 pg/mg creatinine, P < 0.001). After adjustment for age and asthma diagnosis, a greater incidence rate of hospitalization for pain was observed among children with SCD in the highest LTE(4) tertile when compared with the lowest (114 vs. 52 episodes per 100 patient-years, P = 0.038). LTE(4) levels are elevated in children with SCD when compared with controls. LTE(4) levels are associated with an increased rate of hospitalizations for pain.

Markers of bone turnover are associated with growth and development in young subjects with sickle cell anemia

Children with sickle cell anemia (SCA) have low bone mass though bone turnover has not been well described. In this study, growth and pubertal development were assessed twice, 1 year apart, in 80 young subjects with type-SS SCA, while whole body bone mineral content (BMC) and density where measured in a subset (n = 46). Markers of bone turnover were measured at the second visit. Bone formation (alkaline phosphatase) was elevated, whereas bone resorption (deoxypyridinoline) was decreased compared to published data in healthy children. Markers of bone turnover correlated with growth velocity and pubertal development but not with changes in bone mass.

Tissue and Urinary Haemosiderin in Chronic Leg Ulcers

OBJECTIVE

The aim of this study was to assess the relationship between urinary and tissue haemosiderin in chronic leg ulcers, and its value as a diagnostic test for venous ulceration.

METHODS

45 patients with chronic leg ulcers were recruited to the study (24 venous, 6 ischaemic, 6 lymphoedematous, 5 rheumatoid and 4 sickle cell). Punch biopsy of the ulcer edge was taken and early morning urine samples were collected. Positive Prussian-blue urinary haemosiderin granules were measured with a haemocytometer following Perls' staining. The percentage area of histological section staining positively with Perls' was measured using image analysis.

RESULTS

84 urine samples and 46 ulcer biopsies were collected. Urinary haemosiderin was present in 92% of venous ulcer patients, but was absent in the ischaemic ulcer patients (p<0.0001). Significantly more urinary haemosiderin granules were detected in venous ulcer patients compared with patients who had lymphoedema (p<0.05). Tissue haemosiderin was detected in all ulcer types investigated. No correlation was found between the amounts of haemosiderin deposited in the tissue and the amount found in urine (r(2)=0.06).

CONCLUSIONS

Haemosiderin is present in the urine of most patients with venous ulcers but not in ischaemia ulcers.

Urinary hepcidin in congenital chronic anemias

BACKGROUND

Hepcidin, a regulator for iron homeostasis, is induced by inflammation and iron burden and suppressed by anemia and hypoxia. This study was conducted to determine the hepcidin levels in patients with congenital chronic anemias.

PROCEDURE

Forty-nine subjects with anemia, varying degrees of erythropoiesis and iron burden were recruited. Eight children with immune thrombocytopenia were included as approximate age-matched controls. Routine hematologic labs and urinary hepcidin (uhepcidin) levels were assessed. For thalassemia major (TM) patients, uhepcidin was obtained pre- and post-transfusion.

RESULTS

In TM, uhepcidin levels increased significantly after transfusion, demonstrated wide variance, and the median did not significantly differ from controls or thalassemia intermedia (TI). In both thalassemia syndromes, the hepcidin to ferritin ratio, a marker of the appropriateness of hepcidin expression relative to the degree of iron burden, was low compared to controls. In TI and sickle cell anemia (SCA), median uhepcidin was low compared to controls, P = 0.013 and <0.001, respectively. In thalassemia subjects, uhepcidin levels were positively associated with ferritin. In subjects with SCA, uhepcidin demonstrated a negative correlation with reticulocyte count.

CONCLUSIONS

This study examines hepcidin levels in congenital anemias. In SCA, hepcidin was suppressed and inversely associated with erythropoietic drive. In thalassemic syndromes, hepcidin was suppressed relative to the degree of iron burden. Transfusion led to increased uhepcidin. In thalassemia, the relative influence of known hepcidin modifiers was more difficult to assess. In thalassemic syndromes where iron overload and anemia have opposing effects, the increased erythropoietic drive may positively influence hepcidin production.

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.

Urinary endothelin-1 as a marker of renal damage in sickle cell disease

BACKGROUND

Sickle cell disease (SCD) affects the kidney by acute mechanisms as well as by insidious renal medullary/papillary necrosis, resulting in tubular defects, which increase the risk of dehydration and subsequent sickle crisis. Hypoxia has been reported to stimulate endothelin-1 (ET-1) synthesis by endothelial cells and also in the renal tubule.

METHODS

This case-control study measured ET-1 in urine as a marker of its renal synthesis in asymptomatic SCD patients. Baseline plasma and urinary ET-1 levels were measured and followed during a water deprivation study and a subsequent administration of desmopressin.

RESULTS

Urine and plasma levels of ET-1 were elevated in patients with SCD, compared with carefully matched African-French and African controls, and urine ET-1 excretion was associated with a marked urine-concentrating defect. Moreover, urinary ET-1 output was correlated with microalbuminuria in SCD patients.

CONCLUSIONS

ET-1 is known to antagonize the tubular effects of vasopressin and to promote renal scarring; increased renal production of ET-1 could produce nephrogenic diabetes insipidus and dehydration in SCD patients through a combination of fibrosis and functional resistance to vasopressin. This study provides a rationale for trials with endothelin receptor antagonists in sickle cell disease nephropathy.

The measurement of urinary hydroxyurea in sickle cell anaemia

Hydroxyurea is increasingly used in the treatment of sickle cell disease (SCD) although there is little evidence on how best to monitor treatment and compliance. It is also not known why 10-50% patients do not benefit from the drug and whether some of this resistance is because of pharmacokinetic factors. We have developed an assay using mass spectrometry (MS) to measure urinary concentrations of hydroxyurea. We have used this assay to study 12 children and six adults with SCD taking hydroxyurea and found that urinary hydroxyurea was present for at least 12 h following tablet ingestion. Thirty-five urine samples were analysed that were expected to contain hydroxyurea, based on the reported timing of the last dose and hydroxyurea was detected in 29 (83%) of these. There were also marked differences in urinary hydroxyurea concentrations, suggesting pharmacokinetic variability may explain some of the differences in response to hydroxyurea. Urine samples were also analysed by MS for penicillin metabolites and 43 of the 57 (75%) contained phenoxyacetate, suggesting the ingestion of penicillin within the last 12 h. These assays are potentially useful to study hydroxyurea metabolism further, develop optimal dosing regimes and monitor compliance with treatment.

Delayed hemolytic transfusion reaction/hyperhemolysis syndrome in children with sickle cell disease

OBJECTIVE

Alloimmunization in patients with sickle cell disease (SCD) has a reported incidence of 5% to 36%. One complication of alloimmunization is delayed hemolytic transfusion reaction/hyperhemolysis (DHTR/H) syndrome, which has a reported incidence of 11%. In patients with SCD, clinical findings in DHTR/H syndrome occur approximately 1 week after the red blood cell (RBC) transfusion and include the onset of increased hemolysis associated with pain and profound anemia. The hemoglobin (Hb) often drops below pretransfusion levels. In many reported adult cases, the direct antiglobulin test (DAT) remains negative and no new alloantibody is detected as the cause for these transfusion reactions. To date, few pediatric cases have been reported with this phenomenon. The objective of this study was to describe the clinical and laboratory findings of a case series in children who had SCD and experienced a DHTR/H syndrome at our institution.

METHODS

An 11-year retrospective chart review of patients with discharge diagnosis of SCD and transfusion reaction was performed. DHTR/H syndrome was defined as the abrupt onset of signs and symptoms of accelerated hemolysis evidenced by an unexplained fall in Hb, elevated lactic dehydrogenase, elevated bilirubin above baseline, and hemoglobinuria, all occurring between 4 and 10 days after an RBC transfusion. Patient characteristics, time from transfusion, symptoms, reported DAT, new autoantibody or alloantibody formation, laboratory abnormalities, and complications were recorded. Patients with acute transfusion reactions were excluded.

RESULTS

We encountered 7 patients who developed 9 episodes of DHTR/H syndrome occurring 6 to 10 days after RBC transfusion. Each presented with fever and hemoglobinuria. All but 1 patient experienced pain initially ascribed to vaso-occlusive crisis. The DAT was positive in only 2 of the 9 episodes. The presenting Hb was lower than pretransfusion levels in 8 of the 9 events. Severe complications were observed after the onset of DHTR/H: acute chest syndrome, n = 3; pancreatitis, n = 1; congestive heart failure, n = 1; and acute renal failure, n = 1.

CONCLUSIONS

DHTR/H syndrome occurs in pediatric SCD patients, typically 1 week posttransfusion, and presents with back, leg, or abdominal pain; fever; and hemoglobinuria that may mimic pain crisis. Hb is often lower than it was at the time of original transfusion, suggesting the hemolysis of the patient's own RBCs in addition to hemolysis of the transfused RBCs; a negative DAT and reticulocytopenia are often present. Severe complications including acute chest syndrome, congestive heart failure, pancreatitis, and acute renal failure were associated with DHTR/H syndrome in our patients. DHTR/H in the pediatric sickle cell population is a serious and potentially life-threatening complication of RBC transfusion. It is important to avoid additional transfusions in these patients, if possible, because these may exacerbate the hemolysis and worsen the degree of anemia. DHTR/H syndrome must be included in the differential of a patient who has SCD and vaso-occlusive crisis who has recently had a transfusion.

Risk factors for microalbuminuria in children with sickle cell anemia

PURPOSE

To determine the prevalence of microalbuminuria and to establish clinical characteristics associated with microalbuminuria in children with sickle cell anemia.

PATIENTS AND METHODS

Urine samples of all children (homozygous SS) followed in the Medical College of Georgia's Children's Medical Center Sickle Cell Clinic were screened for microalbuminuria. Random samples were obtained from continent patients at routine office visits between September 1996 and November 1999. A retrospective chart survey was performed to determine clinical correlates for microalbuminuria. Medical records were reviewed for age, sex, hemoglobin, and episodes of pneumonia, pain, aplasia, acute chest syndrome, priapism, and avascular necrosis. Demographic and clinical variables were compared with microalbuminuria by univariate and multivariate logistic regression.

RESULTS

One hundred forty-two patients ages 21 months to 20 years made up the study group. The prevalence of microalbuminuria was 19%. Both increasing age and a lower hemoglobin level were found to correlate with microalbuminuria. By multivariate analysis, boys with microalbuminuria were likely to have a lower hemoglobin level and girls with microalbuminuria were likely to be older. None of the following factors were significantly related to microalbuminuria: pain, pneumonia, acute chest syndrome, priapism, avascular necrosis, or aplastic episodes.

CONCLUSIONS

Microalbuminuria is strongly and directly related to age and strongly and inversely related to hemoglobin levels. Identification of risk factors for microalbuminuria may allow earlier intervention to prevent renal complications in patients with sickle cell disease.

Glomerular filtration rate in Nigerian children with homozygous sickle cell disease

The study proposed to assess glomerular filtration rate as determined by endogenous creatinine clearance in steady state Nigeria children with homozygous sickle cell disease and normal controls. Twenty-four hours urinary creatinine clearance was estimated over a 6-month period in 54 steady-state homozygous sickle cell disease and 57 normal control children aged 5 to 13 years. Each child was admitted and a 24-hour urine sample (8.00 am to 8.00 am) was collected both for volume measurement and creatinine concentration determination. Blood was also collected from each child 30 minutes to end of urine collection for plasma creatinine concentration determination, haematocrit and reticulocyte counts. The results were compared between the two groups of children using student's t-test and the chi (X2) square test where necessary. The mean glomerular filtration rates +/- SD (ml/min/1.73 M2) for homozygous sickle cell disease children and normal controls were not significantly different (p > 0.05). Glomerular filtration rate did not differ significantly between the age groups in both patients and normal controls; haematocrits correlated weakly with glomerular filtration rates in the patients (r = +0.213; p < 0.001). Nigerian children with homozygous sickle cell disease who are in steady states have normal glomerular filtration rate that is hardly influenced by increasing age and low haematocrit level.

Ascorbate levels in red blood cells and urine in patients with sickle cell anemia

Ascorbic acid can be important in sickle cell anemia (SCA) because significant oxidative stress occurs in the disease. Ascorbate could contribute to reduction of the increased oxygen free radicals generated in sickle red blood cells (SRBC) and to the recycling of vitamin E in the cells, while renal loss could contribute to the low plasma levels. Evaluation of red blood cell (RBC) and urine ascorbate in SCA has not been reported. Results showed (1) ascorbate levels in SRBC were similar to those in normals; (2) urine ascorbate excretion was increased in 36% of patients; (3) plasma levels of ascorbate were decreased.

CONCLUSIONS

(1) Ascorbate is present in SRBC, most likely due to ascorbate recycling, despite increased free-radical generation. (2) The increase in renal excretion may contribute to the low plasma levels of ascorbate. (3) The presence of ample ascorbate in SRBC and decreased plasma ascorbate suggests that ascorbate movement across the SRBC membrane may differ from normal RBC.

Prevalence of microalbuminuria in children with sickle cell disease

Renal involvement is common in homozygous sickle cell disease (HbSS), including glomerular hypertension and hypertrophy similar to that seen in rodent models of ablative nephrectomy and stage I diabetic nephropathy (DN). The proteinuria in the rodent models is attenuated by angiotensin converting enzyme inhibition (ACEI). Microalbuminuria (MA) is a sensitive marker for renal involvement in DN prior to the development of proteinuria, and is also attenuated with ACEI. Elevated urinary microalbumin/creatinine ratios (U Alb/Cr) >20 mg/g Cr are reported in 39%-43% of adults with HbSS, and studies are ongoing in this age group to assess the effect of attenuated proteinuria by ACEI on long-term renal function. The purpose of this study was to prospectively investigate the prevalence of MA in children with HbSS and determine factors which affect its expression. U Alb/Cr values were measured on spot urine samples in 102 children (aged 2-18 years, mean 9.47+/-4.62, M:F=53:49) by rate nephelometry. Children with prior known proteinuria, hypertension, or fever/pain episode in the last 15 days were excluded. MA was present in 26.5% of all children with HbSS. However, in children between the ages of 10 and 18 years, the prevalence was 46% (similar to the prevalence in adults). There was a strong correlation between patient age and prevalence of MA (P<0.0001) by both univariate and multivariate analysis. However, pain frequency, hospitalization, transfusion program, ferritin levels, and Cr clearance (C(Cr)) did not correlate with prevalence, although C(Cr) (as estimated by Schwartz formula) was elevated in all. We conclude that the prevalence of MA in the 2nd decade of life is similar to that in adults.

Eicosanoids in sickle cell disease: potential relevance of 12(S)-hydroxy-5,8,10,14-eicosatetraenoic acid to the pathophysiology of vaso-occlusion

The monohydroxyeicosanoid 12(S)-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE), which is derived from oxygenation of arachidonic acid by 12-lipoxygenase, is one of the major metabolites in platelets. In a recent study, we have showed that this eicosanoid stimulated basal sickle-red-cell-endothelial-cell adhesion. To understand the pathophysiologic significance of 12-HETE, we measured the levels of this eicosanoid in plasma and urine from children with sickle cell disease. We found that as compared with controls, plasma 12-HETE levels are increased in patients with sickle-cell disease in the steady state, and are increased further during vaso-occlusive crises. Urinary 12-HETE levels were also increased during the steady state. We also assessed plasma levels of soluble P-selectin (another potential marker for platelet activation), and found changes in the levels of this marker similar to those seen with plasma 12-HETE. In additional studies, we found that 12-HETE enhanced hypoxia-induced sickle-red-cell-endothelial adherence, and that this effect was mediated by potentiation of agonist-induced upregulation of the expression of the mRNA for vascular cell adhesion molecule-1 (VCAM-1) in endothelial cells. Because 12-HETE appears to enhance both basal and agonist-induced sickle-red-cell adhesion, this metabolite could potentially play a role in the pathogenesis of the vaso-occlusive crisis (VOC) in sickle-cell disease.

[Arterial pressure and urinary excretion of albumin in adults with sickle cell disease]

OBJECTIVE

The increase of urinary albumin excretion could be associated with morbidity in patients with sickle cell disease. The objective of this study was to evaluate the relation between blood pressure and urinary albumin excretion, and to estimate the prevalence of hypertension according to the level of urinary albumin excretion.

METHODS

A cross-sectional study was carried in 77 patients with sickle cell disease (48 patients with haemoglobin SS, 29 with haemoglobin SC) et 30 controls with haemoglobin AA. The patients with sickle cell disease were divided into 3 groups according to urinary albumin excretion: less than 30 mg daily (group I: normoalbuminuria); from 30 to 300 mg daily (group II: microalbuminuria); above 300 mg daily (group III: macroalbuminuria). All AA selected controls had normoalbuminuria (group IV).

RESULTS

In normoalbuminuric patients, the average of blood pressure was significantly lower in patients with sickle cell disease than in controls (respectively 115.0 +/- 8.1 vs 132.1 +/- 15.1, p = 4.10(-6) for systolic pressure and 67.2 +/- 8.0 vs 78.8 +/- 9.8 mmHg, p = 10(-4) for diastolic pressure). There was a positive relation between urinary albumin excretion, even moderate (values < or = 300 mg daily) and blood pressure in SS patients (r = 0.40, p < 0.02 for systolic and r = 0.54, p < 0.01 for diastolic pressure) and in SC patients (r = 0.74, p < 0.001 and r = 0.58, p < 0.01). The prevalence of hypertension was 0% in group I, 25% in group II and 66% in group III.

CONCLUSION

The positive association between blood pressure and urinary albumin excretion suggests that the latter should be taken into account in sickle cell disease's follow up.

Decreased urinary excretion of beta-glucuronidase in sickle cell anemia in Nigeria

The activities of five lysosomal hydrolases--namely beta-glucuronidase, beta-hexosaminidase, beta-galactosidase, alpha-galactosidase, and alpha-mannosidase--were measured in the plasma and urine of children (ages, 7 to 15 years) with sickle cell anemia (n = 11) and controls (n = 11) from Jos, Nigeria. The presence of SS hemoglobin was confirmed by electrophoresis of red cell hemolysates. Albuminuria was absent in all of the patients with sickle cell anemia. The creatinine-indexed urinary activity level (units of enzyme activity/milligrams creatinine) and the fractional enzyme excretion (FEE) value, which is defined as the ratio of enzyme clearance to creatinine clearance, were determined for each of the five lysosomal enzymes and compared between the two groups. The mean FEE values for beta-glucuronidase and alpha-galactosidase in the sickle cell patients were 10- and 3.5-fold lower, respectively, than the corresponding control values, and these differences were statistically significant (p < .03) for both enzymes; however, beta-hexosaminidase, beta-galactosidase, and alpha-mannosidase levels in urine were not different between the two groups. When indexed to creatinine, a comparison of the urinary enzyme levels of control and sickle cell patients showed significant differences for beta-glucuronidase (p < .01) and alpha-galactosidase (p < .05) but not for the other three enzymes. Differences in level of plasma enzyme activity between control and sickle cell patients were not significant, except for alpha-galactosidase (p < .05), which was increased slightly (25%) in the sickle cell group. These data indicate that there may be abnormalities in the metabolism of lysosomal enzymes in the kidneys of patients with sickle cell anemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Elevated urinary levels of thromboxane and prostacyclin metabolities in sickle cell disease reflects activated platelets in the circulation

There is evidence for increased factor VII turnover and the associated increased thrombin generation and fibrinolytic activities in sickle cell disease (SCD) that may affect in vivo platelet and endothelial cell reactivity. We studied the release of specific eicosanoids that are indicative of in vivo platelet activation and endothelial cell injury. The circulating and urinary levels of 2,3-dinor thromboxane B2(2,3-dinor-TxB2),TxB2,PGI2 [as 6-keto-PGF1 alpha], and PGE2 were measured in 15HbSS patients, eight HbAA non-haemolytic anaemic individuals and 12 healthy HbAA controls using specific RIAs. The mean urinary 2,3-dinor-TxB2 in the HbSS patients was significantly higher than in both the healthy HbAA and the anaemic controls. 6-keto-PGF1 alpha was undetected in the urines of the healthy HbAA controls, but was measured insignificant amounts in the HbSS and the HbAA anaemic patients. The urinary concentrations of PGE2 and TxB2 in HbSS patients' samples were also significantly higher than those of both control groups (P < 0.05). PGE2 and TxB2 levels were below the detection limit in the plasmas of the HbAA subjects, but were measurable in the HbSS and HbAA anaemic plasmas. The plasma level of 6-keto-PGF1 alpha in the HbSS patients was also significantly higher than in the control groups. The data indicates a persistent inflammatory process in the HbSS patients, and is consistent with the hypothesis that there is platelet and endothelial cell activation in SCD.

Plasma and urinary leukotrienes in sickle cell disease: possible role in the inflammatory process

Sickle cell (HbSS) disease is associated with rheological and inflammatory stresses within the microcirculation. In order to determine the role of leukotrienes in the inflammatory processes in HbSS patients, we analysed plasma and urine levels of leukotrienes (LT); LTB4, LTC4, LTD4, and LTE4 as indicators of their in vivo metabolism. Plasma and urine level samples of 15 HbSS patients in steady-state and age-matched healthy, homozygous (HbAA) controls were extracted for leukotrienes and quantitated by HPLC. Control plasma level of leukotrienes (mean +/- SEM, ng ml-1) were: LTB4, 8.95 +/- 0.26; LTC4, 7.24 +/- 0.21; LTD4, 11.42 +/- 0.40; and LTE4, 14.51 +/- 0.50. Corresponding values for HbSS patients were: LTB4, 6.15 +/- 0.42; LTC4, 13.61 +/- 1.45; LTD4, 6.44 +/- 0.51 and LTE4, 4.97 +/- 0.37. The differences were significant at P < 0.05. Urine levels (mean +/- SEM, ng mmol-1 creatinine), for controls were: LTB4, 10.60 +/- 0.35; LTC4, 360.0 +/- 9.82. Values for HbSS urine were: LTB4, 27.50 +/- 3.33; LTC4, 356.0 +/- 17.87; LTD4, 69.90 +/- 14.51. LTD4 was not detected in control urine. These results suggest that sickle cell patients may exhibit impaired ability to catabolize LTC4 in plasma during steady state conditions. This altered metabolism may contribute to the persistent stress of the microcirculation, and is probably related to the abnormal microvascular rheology of sickle blood cells.

Increased in vivo production of thromboxane in patients with sickle cell disease is accompanied by an impairment of platelet functions to the thromboxane A2 agonist U46619

Thrombosis represents an important cause of mortality in patients with sickle cell disease, in addition to the complications caused by the primary defect of inherited abnormal hemoglobin. To study the involvement of platelets in these complications, we assessed the biosynthesis of thromboxane A2 in samples from 49 patients with sickle cell disease and in 33 control subjects. The urinary excretion of the major arachidonic acid metabolite of platelet origin (11-dehydro-thromboxane B2) and of the vascular endothelial cell (2,3-dinor-6-ketoprostaglandin F1 alpha) were very significantly increased (p < 0.0002) in the patients. In a small group of patients (n = 14), we further investigated the ex vivo response of their platelets to U46619, a stable analogue of thromboxane A2. We observed decreased aggregation and [14C]serotonin release compared with control (p < 0.05); similarly, we found impaired p47 protein phosphorylation (p < 0.05). In contrast, platelets from these patients responded normally to thrombin (0.1 unit/mL). In vivo desensitization of platelets from these patients to thromboxane may constitute a form of regulation that may prevent the propagation of aggregation by this potent inducer, as has been hypothesized in in vitro studies. Our results may also provide a rationale for using antiplatelet drugs in the prophylaxis of thrombotic complications in sickle cell patients.

Urinary magnesium excretion in steady-state sickle cell anaemia

Previous reports indicate that individuals with sickle cell anaemia may be magnesium deficient. The role of renal excretion of magnesium in the pathogenesis of this low magnesium status was investigated in 25 patients with sickle cell anaemia (sicklers) in the steady state and in 25 age- and sex-matched controls with haemoglobin genotype AA. The clearance, excretion fraction and excretion rates of magnesium were enhanced in the sicklers. These patients also had significantly lower erythrocyte and plasma magnesium concentrations than the controls. However expressed, urinary magnesium showed a significant positive correlation with plasma magnesium and a weak negative correlation with erythrocyte magnesium. Furthermore, a significant negative correlation was observed between erythrocyte and plasma magnesium in the sicklers. These results suggest that urinary disposal of magnesium in rates and amounts inappropriate to the body stores of the cation may be one of the mechanisms accounting for hypomagnesaemia and low erythrocyte magnesium content in patients with sickle cell anaemia.

Maintenance of normouricaemia during adolescence in sickle-cell anaemia

Aspects of uric acid metabolism were investigated during adolescence in 122 patients with sickle-cell anaemia in the steady state and 52 matched controls with normal haemoglobin AA. Plasma urate concentrations were significantly lower (P less than 0.02) in male patients than in male controls. No significant differences were observed between either female patients and female controls or total patient group and total control group. Further study in subgroups of the subjects showed that all indices of urinary urate excretion in male patients were significantly increased over male controls or female patients. The increases in these indices in female patients over female controls were not statistically significant. Significant inverse correlations were also found between plasma urate and either renal urate clearance (r = -0.483, P less than 0.02) or fractional urate excretion (r = -0.398, P less than 0.05) in the patients. These findings indicate that patients with sickle-cell anaemia maintain normouricaemia during adolescence by increasing renal urate disposal. This process appears to be more efficient in the male patients.

Urea kinetics: comparison of oral and intravenous dose regimens

Urea kinetics were measured on two separate occasions in five adults with normal haemoglobin genotype (HbAA) and in four who were homozygous for sickle cell disease (HbSS). Prime/intermittent doses of [15N15N]urea were given orally on one occasion and intravenously on the other. In three of the nine individuals there appeared to be significant hydrolysis of the oral dose of urea before absorption, leading to spurious results for the urea kinetics. When only the studies in which isotope was given intravenously were considered, there was a difference in the rate at which urea-N was salvaged, with more urea-N being salvaged by HbSS subjects than HbAA. It is concluded that the oral presentation of isotope can be used to measure urea kinetics provided care is taken to exclude those subjects who are likely to display upper intestinal hydrolysis, and that there are differences in aspects of urea kinetics between HbAA and HbSS which may be of metabolic importance.

Renal involvement in sickle cell-beta thalassemia

Renal function studies were performed in 41 patients with sickle cell-beta thalassaemia (S/b thal) and compared to 14 normal controls and 8 sickle cell (SS) patients. Polyuria, hyposthenuria and mild proteinuria were common in both S/b thal and SS patients. A renal concentrating defect was manifest in all patients studied, and in 4 of the 7 S/b that patients tested, an abnormal acidification test was found. A statistically significant negative correlation (n = 19, r = -0.48, p less than 0.05) was noted between creatinine clearance (CCr) and age for the patients over 30 years. There was no correlation between hemoglobin and CCr; on the contrary, a statistically significant negative correlation was found between CCr and hemoglobin F (n = 29, r = -0.428, p less than 0.05) Our S/b thal and SS patients showed a decreased daily excretion of sodium, calcium, phosphate and magnesium and lower serum magnesium levels than the controls. One third of the S/b thal patients showed hyperuricosuria, and a statistically significant negative correlation was noted between serum uric acid and its fractional excretion in all S/b thal patients (n = 41, r = -0.450, p less than 0.01). Serum phosphate levels were independent of age. A statistically significant positive correlation was found between the tubular reabsorptive capacity for phosphate and the number of painful crises per year (n = 33, r = 0.836, p less than 0.001). We conclude that renal involvement in the double heterozygous state is as severe as in homozygous sickle cell disease.

Usefulness of empiric chest radiography and urinalysis testing in adults with acute sickle cell pain crisis

STUDY OBJECTIVE

To determine the usefulness of obtaining routine chest radiographs and urinalyses on adults presenting to the emergency department in acute sickle cell pain crisis. The hypothesis tested is that in some adult sickle cell patients, sickle cell pain crises are precipitated or accompanied by acute infection that may be clinically occult and that routine screening for pulmonary or urinary tract infection would identify some of these precipitating illnesses.

DESIGN

Prospective clinical study.

SETTING

A university hospital ED.

PATIENTS

All patients more than 14 years old with S-S, S-C, or S-beta-thalassemia sickle hemoglobinopathies who presented to the ED with acute nontraumatic painful complaints during a six-month period.

INTERVENTIONS

All patients underwent posteroanterior and lateral chest radiography, routine urinalysis, and CBC count with reticulocyte count. A standard questionnaire for localizing symptoms of systemic, pulmonary, and urinary tract infection was completed for each patient. Urine cultures were ordered on all patients with voiding symptoms, flank pain, and/or more than 5 WBCs or RBCs per high-power field on urinalysis. Physical examination for evidence of pulmonary and urinary tract infection was carefully performed and recorded for subsequent analysis.

RESULTS

Seventy-one patients with 134 ED presentations were studied over a six-month period. Eight diagnoses of acute pneumonia were made. Four of these patients complained of chest pain (50% vs 48% overall) and three had shortness of breath (38% vs 21%). None of these patients complained of fever or symptoms of upper respiratory illness. Ten diagnoses of urinary tract infection were made. Four of these patients complained of dysuria and frequency; three complained of flank pain. Eleven of the 18 infections (61.1%) did not have a typical history for or suggestive physical or laboratory findings of bacterial infection.

CONCLUSION

In sickle cell disease patients with pain crisis, routine chest radiography and urinalysis may be clinically useful and cost effective in the early diagnosis of crisis-related infection.

Determinants of nocturnal enuresis in homozygous sickle cell disease

The determinants of nocturnal enuresis in homozygous sickle cell (SS) disease have been investigated in 16 enuretic and 16 age and sex matched non-enuretic children. Overnight fluid deprivation tests (8pm-8am) demonstrated no significant difference in maximum urine osmolality or urine volumes, although the latter tended to be higher in the enuretic children. Maximum functional bladder capacity, estimated by maximum voided volume during oral fluid loading, was lower and the ratio of overnight urine volume to maximum functional bladder capacity higher in the enuretic than the non-enuretic group. Enuretic children were more likely than non-enuretics to be considered deep sleepers by their family. High urine volumes may contribute to nocturnal enuresis in SS disease, although the similar values in enuretic and non-enuretic children implies that additional factors determine the presence of enuresis. Low maximum functional bladder capacity, and a high ratio of overnight urine volume to maximum functional bladder capacity, appear to be important determinants.

Proteinuria in sickle cell trait and disease: an electrophoretic analysis

Using ultrafiltration and SDS-PAGE, abnormal urinary protein excretion was found in 25.4% of 189 persons with sickle cell disease and trait, but none of 72 controls. Based upon molecular weight of urinary proteins, underlying renal lesions were classified as glomerular, tubular, or both. Altered protein excretion appeared at an early age, was more abnormal in older subjects, and was related to the severity of sickle cell disease (SS greater than SC = S/beta Thal greater than AS). Since none of the subjects had yet developed clinically significant renal disease, SDS-PAGE may permit early detection of patients who require careful follow-up or aggressive therapy.

Altered vascular reactivity in sickle hemoglobinopathy. A possible protective factor from hypertension

Patients with sickle cell anemia have considerably less hypertension than the black population in general. Factor(s) offering "protection" from hypertension in these patients remain unknown. Hormonal and hemodynamic parameters involved in blood pressure regulation were evaluated in normotensive, stable sickle cell patients and black nonsickle normotensive controls. There was no difference in systolic, diastolic, or mean arterial blood pressure between the two groups. The characteristic hemodynamic findings of increased cardiac index, renal plasma flow, and plasma volume were observed in the sickle cell patients. Urinary sodium excretion was comparable on an ad libitum, high sodium, and low sodium diet. In contrast, plasma renin activity was greater in sickle cell patients at all levels of sodium intake in both supine and upright positions. These findings suggested possible altered vascular responsiveness to endogenous angiotensin II. Plethysmography revealed that sickle cell patients had greater forearm blood flow than normal controls and black nonsickle chronic anemic controls at rest, during cold stimulation, and during exercise. Forearm vascular resistance was significantly lower in the patients and did not increase with cold-induced, sympathetic-mediated stimulation. To assess these findings more directly, the pressor response to the exogenous administration of graded doses of angiotensin II and norepinephrine was measured. There was a marked decrease in the pressor response to angiotensin II but not to norepinephrine in the sickle cell patients. The findings in these studies indicate fundamental differences in blood pressure control in the sickle cell patient, probably at the vascular level.

Zinc status in children and young adults with sickle cell disease

Previous studies have suggested an association of zinc deficiency and short stature in some children and adults with sickle cell disease (SCD). As a result, zinc supplementation has been recommended for these patients. The mechanism for zinc deficiency in certain patients with SCD is unknown, although renal loss of zinc has been suggested as a contributing factor. The zinc status of 29 subjects with SCD and 18 black controls was studied. No evidence of zinc deficiency in our population with SCD was found when plasma and cellular zinc levels were measured. Likewise, levels of two zinc-dependent enzymes, alkaline phosphatase and delta-aminolevulinic acid dehydratase, were normal in these subjects with SCD. Although adolescent subjects with SCD tended to be shorter than control subjects, there was no correlation between the height-forage z score and plasma zinc levels (r = -.31). It was concluded that zinc deficiency was not present in our population with SCD, and that there was no correlation between plasma zinc levels and the height-for-age z score in growing adolescent patients with SCD. These findings suggested that zinc supplementation may not be necessary in all patients with SCD.

Urinary creatine: biochemical indicator for evaluation of sickle cell crises

In a patient with known sickle cell beta 0-thalassemia we measured serum lactate dehydrogenase (LD) activity and 24-h urinary creatine excretion rate as markers to evaluate sickle cell crises. We believe that a distinction based on biochemical findings can be made between hemolytic and painful vaso-occlusive sickle cell crises with muscular involvement. To assess hemolytic crises by objective biochemical measures, we have used assay of LD activity, and to assess painful crises with muscular involvement objectively, the 24-h urinary creatine excretion rate. We conclude that hemolytic crises are characterized by high serum LD activities. Furthermore, we conclude that--at least in this patient--painful crises are accompanied by high 24-h urinary creatine excretion rates. Our findings suggest that muscle involvement may play an important role in painful vaso-occlusive sickle cell crises.