Is Screening for Microalbuminuria Warranted in Children with Sickle Cell Hemoglobinopathies?

Abstract Renal impairment occurs in adults and children with sickle cell disease. Microalbuminuria (MA) defined as albumin excretion >2.9 mg/dl in random urine sample or 30–300 mg in 24 hour urine collection is an early, sensitive indicator for glomerulopathy in both diabetes mellitus and sickle cell disease. Therefore, we conducted a universal screening in our patients (pts) with sickle cell hemoglobinopathies in order to identify the prevalence of MA and other indicators of early renal impairment. Children and young adults with hemoglobin SS, SC, Sβ+thalassemia and Sβ0thalassemia, ages 4–21 years (yrs), had urinalyses and random urine measurements for protein, microalbumin, and creatinine. All were in good state of health, free of pain, and without prior diagnosis of renal dysfunction when the samples were obtained. Serum electrolytes, creatinine, osmolality, and 24-hour urine collection for protein, microalbumin, β2-microglobulin, creatinine, and electrolytes were done in pts with abnormal urine samples. There were 101screened pts (53 males; 76 SS, 20 SC, 3Sβ0, and 2 Sβ +). Nineteen pts had MA detected by random urine. MA was confirmed in 24-hour samples in 46% of studied pts. In addition to MA, tubular proteinuria (increased β2-microglobulin) was detected in 1 pt, isolated hematuria in 3 and increased urine protein/creatinine (>0.2) in 4. From the MA+ pts, 15 had SS (19.7% of SS group) and 4 had SC (20% SC group). 25% of children 10 yrs of age or older had MA (mean± standard deviation MA 2.83±3.94), as compared to 6% of younger children (mean 1.21±0.80), (p=0.02). African Americans had lower incidence of MA (11.4%), compared to other children of Haitian (21.3%), Hispanic Caribbean (25%), and other Caribbean (28.5%) descent (p=not significant [NS]). There was no correlation between MA and history of stroke, acute chest syndrome/asthma, brief use of non-steroidal anti-inflammatory medications, hemoglobin or white cell values. From the subgroup of 16 pts on hydroxyurea, 11 were 10 yrs of age or older; of these, 5 (45.5%) had MA, compared to 21% of the same age non-treated group (p=NS). We analyzed the effect of age at onset of chronic transfusions and presence of MA. Six transfused pts had MA (age at start of transfusion 8.6–13.5 yrs, mean 11 yrs; mean MA 5.3±3.4), while there were 15 MA free pts (age 0.8–12.4 yrs, mean 7 yrs; mean MA 1.4±0.6), suggesting that early age at start of chronic transfusions may be protective for MA (p=0.0004). We conclude that: (1) urine screening of children with sickle cell hemoglobinopathies 10 yrs or older is recommended, (2) chronic transfusions starting at an early age may protect against MA, and (3) validity of random versus 24-hour urine collections in determining MA should be further investigated. Studies to further define the risk factors, prognosis, and intervention in children with sickle cell hemoglobinopathies are warranted

Survival and complications of cuffed catheters in children on chronic hemodialysis

Central venous catheters are being increasingly used as hemodialysis vascular access. We evaluated catheter survival, outcome predictors, and complications in a total of 36 catheters used in 13 children and young adults undergoing chronic maintenance hemodialysis through catheter for a duration of 10.4±5.6 months. Reasons for catheter failure were: thrombosis 12 of 36 (33%), infection 6 of 36 (17%), and extrusion 2 of 36 (5.4%). Catheters were lost to infection and thrombosis at 1.1 and 2.2 episodes per 1,000 catheter days, respectively. Symptomatic infections, Gram-negative and polymicrobial sepsis increased the risk of catheter failure. Most of the thrombotic episodes occurred in patients with inherent thrombotic tendency. The survival of the 36 catheters was 62% at 1 year. The survival of 13 randomly chosen catheters, 1 from each patient, was 85% at 1 year. The time from insertion to first complication correlated significantly with the outcome (P<0.03). We conclude that central venous catheters are still associated with a high rate of failure and may be a regular access choice only in a selected patient population with no inherent thrombotic tendency and no other option available for long-term hemodialysis

Erratum to: Serum cystatin C levels in children with sickle cell disease

In the introduction, the expanded form of CSSCD should read Cooperative Study of Sickle Cell Disease (CSSCD) and not Comprehensive Study of Sickle Cell Disease

Serum cystatin C levels in children with sickle cell disease

Patients with sickle cell disease (SCD) may develop kidney dysfunction from childhood. The purpose of this study was to examine the value of serum cystatin C as a marker for glomerular filtration rate (GFR) in children with SCD, as compared to serum creatinine and creatinine clearance (CrCl). Twenty children (ages 9–21, ten males) with SCD with and without albuminuria were studied. The mean serum cystatin for the whole group was 0.89 mg/l (0.5–1.7 mg/l). Mean serum cystatin C was significantly different among the children with proteinuria (n=4), microalbuminuria (n=5), and without albuminuria (n=11) (1.25 mg/l, 0.84 mg/l, and 0.78 mg/l, respectively). The mean GFR derived from serum cystatin was significantly different among these subgroups, becoming abnormal in the proteinuric cohort (63 ml/min per 1.73 m2), in contrast to 94 for the microalbuminuric, and 103 for the normal subgroups. Serum creatinine (mean: 0.58 mg/dl, range: 0.3–1.1) did not change significantly with the level of albuminuria. Mean CrCl remained normal to increased within the subgroups, (133 ml/min per 1.73 m2 for those with proteinuria, 144 for those with microalbuminuria, and 163 for the normal subgroup). We conclude that serum cystatin C correlates with the level of albuminuria and may be a reliable method to measure renal function in SCD