Current Pediatric Reviews - Volume 3, Issue 2, 2007

Renal tubular acidosis (RTA), a clinical syndrome with hyperchloremic metabolic acidosis with normal anion gap, is an uncommon and sometimes overlooked condition. It may have multiple causes, some sporadic, some genetically transmitted; some are isolated or may be associated with other renal or systemic pathologies or diseases. All these factors add to the complexity of recognition and management of this extended range of conditions. We hereby describe several children with different types of RTA, illustrating the different mode of presentations and some of the etiologies. Pathophysiology is reviewed, as well as the practical approach to the diagnosis and management. In addition, recent genetically identified conditions are reviewed, with emphasis on increasingly recognized association with other systems involvement.

Hypertension is a major cause of morbidity and mortality throughout the world and an independent risk factor for cardiovascular disease. Although the incidence of hypertension is significantly greater in adults than children, recent trends reveal a rising percentage of children with high blood pressure. Coincident with the dramatic increase of the number of children with hypertension has been a growing field of knowledge regarding novel causes and therapeutic options for children with high blood pressure. Most reviews in pediatric hypertension focus on the many traditional causes of hypertension in children including renovascular disease, renal parenchymal disease, medication usage, endocrine causes (e.g. hyperthyroidism), and cardiovascular causes (e.g. coarctation of the aorta). However, recent research suggests that nontraditional causes of hypertension including chronic inflammation, low nephron number, prematurity/low birth weight, malnutrition, obesity (as part of the metabolic syndrome), hyperinsulinemia/insulin resistance, elevated uric acid, and dietary factors may be more common than previously thought. There are also innovative concepts in the treatment of childhood hypertension, including behavioral and combination drug therapy. In a rapidly evolving field and epidemic of children developing high blood pressure, it is therefore imperative for the generalist and specialist to be cognizant of the many changes occurring in the pathogenesis and management of childhood hypertension.

Approximately 20% of all children will suffer from wheezing illnesses, and in 1-3% of all infants, respiratory distress is severe enough to require hospitalization. As wheezing infants form a heterogeneous group with different phenotypes and outcomes, it is still a challenge to identify those who will go on wheezing to develop asthma. In order to facilitate the prediction of later asthma, algorithms have been developed for clinical use. The algorithms validated this far are based on personal atopic findings and the parental history of asthma, and blood eosinophilia has been the only laboratory marker included. In this review, we will focus on the role of respiratory viruses, eosinophil activation markers, specific immunoglobulin E antibodies, and skin prick tests, as early life predictors of persistent wheezing and asthma. According to recently published results, rhinoviral infection seems to carry a high risk for persistence of wheezing. Sensitization to inhalant allergens in infancy strongly increases the risk for later respiratory allergy. Eosinophil activation markers seem not to offer significant additional value over blood eosinophils. Determination of viral etiology of wheeze, and/or screening for early sensitization to inhalant allergens in individuals with no clinically evident atopy might be of use in identifying future asthmatics.

Diabetes mellitus type 1 (T1DM), the most common variant of the disease in childhood, requires a wellinformed patient and/or parents, as well as an enthusiastic diabetologist. This paper notes that disease compensation is influenced by several diverse factors of which basic therapeutic components include intensified insulin therapy, diet and regular physical activity. The authors engage in the issues of T1DM complications as well as the adverse effects of common organic diseases in childhood on glycemic profiles and patient's psyche. A supporting family background and a fusion of medical carers involving nutritional therapists, nurses, physiotherapists, education supervisors and the diabetologist, lead to the successful management of this increasingly common childhood illness.

Preterm newborns weighing less than 1500 g (very low birth weight infants, VLBW) represent a critical population with high prevalence of morbidities, often requiring hemodynamic stabilization. Dopamine is a natural cathecolamine widely used for this purpose because it exerts pleiotropic anti-shock effects on cardiovascular, renal and endocrine systems, acting on adrenergic and dopaminergic receptors. Dopamine is a first choice drug in VLBW infants for inotropic support and optimisation of renal and splanchnic perfusion, mostly indicated for the treatment of hypotension, symptomatic patent ductus arteriosus and renal failure. Dopamine reversibly suppresses pituitary functions in adults but its effects on endocrine balance have been poorly studied in VLBW infants. Recent studies showed a dose-dependant reduction of TSH and T4 plasmatic levels in dopamine-treated VLBW infants and a positive correlation between dopamine infusion and incidence of transient hypothyroxinemia of prematurity. Further studies demonstrated that dopamine infusion also reduces PRL secretion in VLBW infants. TSH, T4 and PRL suppression rapidly reverses after dopamine withdrawal, when a significant hormonal rebound is observed. Therefore, such iatrogenic suppression probably cannot involve long-term injuries and T4 substitutive administration appears unecessary during short course dopamine treatment. Recent observations suggest that dopamine infusion can prevent early diagnosis of congenital hypothyroidism (CH) when screening programs are merely based on TSH plasmatic levels. Considering the severe neurodevelopmental outcome of undiagnosed CH, other screening strategies should be considered in treated neonates, such as simultaneous T4 and TSH testing and hormonal re-evaluation after dopamine discontinuation. A final issue of this review regards a possibile role of dobutamine as an alternative safer inotropic drug.

Intrahepatic cholestasis of pregnancy (ICP) is a clinical syndrome of unknown pathophysiology, occurring during the second half of pregnancy and persisting until delivery. The incidence of ICP varies from 0.1% to 1.5% of pregnancies in Europe, North America and Australia and from 9.2% to 15.6% in South American countries such as Bolivia and Chile. This syndrome has been associated with increased foetal distress, intrauterine death, premature delivery, perinatal mortality and, more recently, with the occurrence of respiratory distress syndrome in the newborn infant. Bile acids (BA) are supposed to be the main mediators for these complications because ICP seriously impairs the placental clearance of foetal BA leading to a dangerous accumulation of these compounds within the foetus and the newborn. Cholestatic pregnancies have to be considered high risk ones, recent reports showing that BA can interfere with surfactant metabolism and are particularly harmful for the developing lung. This review summarizes existing literature data on this topic with particular emphasis on bile acids-induced lung injury. The authors discuss possible mechanisms of lung damage and highlight future research perspectives in this field.