Prevalence and clinical correlates of microalbuminuria in children with sickle cell disease.

Sickle cell disease (SCD) is associated with a large spectrum of renal abnormalities, one of which, microalbuminuria/proteinuria (MA/P), is a known predictor of end-stage renal disease. We studied 90 children with SCD (57% male; mean age 11.4 +/- 5.2 years) to determine the prevalence and examine clinical correlates of MA/P. The average of two spot urine microalbumin-to-creatinine samples obtained 6 months apart was recorded. Medical records were reviewed for demographic and biochemical data. Medication use, resting office blood pressures (BP), vaso-occlusive pain crises (VOC), and monthly transfusions were recorded. Fourteen children (15.5%) had MA/P. Hemoglobin (Hb) levels were significantly lower in the children with MA than in those without MA/P (8.8 +/- 1.1 vs. 9.8 +/- 1.4 g/dL, respectively) and were significantly correlated with MA (rho = 0.24, p = 0.03). Children with MA were more likely to have abnormal BP (p = 0.058), with 5/14 being hypertensive or pre-hypertensive. In a multivariate logistic regression model of MA, both Hb and BP classification remained in the final model. MA is a simple screening biomarker of early kidney injury in children with SCD. Larger studies to evaluate predictive factors of MA and the relationship to BP are needed.

Hypertension in Childhood Nephrotic Syndrome.

Arterial hypertension (HTN) is commonly encountered by clinicians treating children with steroid sensitive (SSNS) and steroid resistant nephrotic syndrome (SRNS). Although the prevalence of HTN in SSNS is less documented than in SRNS, recent studies reported high prevalence in both. Studies have estimated the prevalence of HTN in different patient populations with NS to range from 8 to 59.1%. Ambulatory HTN, abnormalities in BP circadian rhythm, and measures of BP variability are prevalent in patients with NS. Multiple mechanisms and co-morbidities contribute to the pathophysiology of HTN in children with NS. Some contributing factors are known to cause acute and episodic elevations in blood pressure such as fluid shifts, sodium retention, and medication side effects (steroids, CNIs). Others are associated with chronic and more sustained HTN such as renal fibrosis, decreased GFR, and progression of chronic kidney disease. Children with NS are more likely to suffer from other cardiovascular disease risk factors, such as obesity, increased measures of arterial stiffness [increased carotid intima-media thickness (cIMT), endothelial dysfunction, increased pulse wave velocity (PWV)], impaired glucose metabolism, dyslipidemia, left ventricular hypertrophy (LVH), left ventricular dysfunction, and atherosclerosis. Those risk factors have been associated with premature death in adults. In this review on HTN in patients with NS, we will discuss the epidemiology and pathophysiology of hypertension in patients with NS, as well as management aspects of HTN in children with NS.

Clinical, demographic, and laboratory characteristics of children with nephrolithiasis.

While the incidence of pediatric kidney stones appears to be increasing, little is known about the demographic, clinical, laboratory, imaging, and management variables in this patient population. We sought to describe various characteristics of our stone-forming pediatric population. To that end, we retrospectively reviewed the charts of pediatric patients with nephrolithiasis confirmed by imaging. Data were collected on multiple variables from each patient and analyzed for trends. For body mass index (BMI) controls, data from the general pediatrics population similar to our nephrolithiasis population were used. Data on 155 pediatric nephrolithiasis patients were analyzed. Of the 54 calculi available for analysis, 98 % were calcium based. Low urine volume, elevated supersaturation of calcium phosphate, elevated supersaturation of calcium oxalate, and hypercalciuria were the most commonly identified abnormalities on analysis of 24-h urine collections. Our stone-forming population did not have a higher BMI than our general pediatrics population, making it unlikely that obesity is a risk factor for nephrolithiasis in children. More girls presented with their first stone during adolescence, suggesting a role for reproductive hormones contributing to stone risk, while boys tended to present more commonly at a younger age, though this did not reach statistical significance. These intriguing findings warrant further investigation.

Blood pressure reclassification in adolescents based on repeat clinic blood pressure measurements.

The common assumption is that blood pressure (BP) will decrease on subsequent readings. The objective of this study is to examine the prevalence and direction of BP classification change with repeat measurements and compare common clinical characteristics of groups of patients who do and do not have a change in BP classification. A nationally representative subsample of 1725 adolescents aged 13 to 18 years from the National Health and Nutrition Survey were analyzed. Three BP measurements were obtained. Patients were classified based on the first and the average of 3 BP measurements as having normal BP, hypertension, and/or prehypertension. Of the 1725 adolescents, 1569 (90.9%) maintained BP classification, 107 (6.2%) had a reduction in their classification, and 49 (2.9%) had an increase in their classification. Comparing the two groups that changed BP classification to the group without change, C-reactive protein and body mass index (BMI) z score were significantly higher in the groups that had a change in BP classification (P=.02 and <.001, respectively). After adjusting for other variables, higher BMI value was significantly associated with change in BP classification. With repeat measurements, the majority (~91%) did not have a change in classification. Obesity was a significant predictor of the 9% that had a change in classification. Repeat BP measurements in obese adolescents may lead to more accurate classification of BP status.

Hypertension and obesity: epidemiology, mechanisms and clinical approach.

Obesity-related hypertension in pediatric patients is becoming more prevalent around the world as a consequence of the childhood obesity epidemic. Hypertension and the metabolic abnormalities associated with obesity will significantly increase the health risks for these children as they grow into adulthood. The pathophysiology of obesity-related hypertension is complex, and multiple potential mechanisms likely contribute to the development of higher blood pressure in obese children. These include hyperinsulinemia, activation of the renin-angiotensin-aldosterone system, stimulation of the sympathetic nervous system, abnormalities in adipokines such as leptin, direct effects of perinephric fat on the renal parenchyma, and cytokines acting at the vascular endothelial level. As in any child with elevated blood pressure, diagnostic evaluation should focus on confirmation of hypertension, determine if an underlying cause can be identified and whether hypertensive target organ damage is present. Therapy should begin with lifestyle modifications, but will often need to include one or more antihypertensive medications.