Dopamine Administration in Very Low Birth Weight Preterm Infants:Emerging Issues on Endocrine Effects

Abstract

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. PART 1. DOPAMINE AND DOBUTAMINE ADMINI-STRATION IN PRETERM INFANTS Clinical BackgroundPreterm infants weighing at birth less than 1500 g are referred to as very low birth weight (VLBW) infants and presently account for about 1-3 % of all neonates [1, 2]. However, they represent a widening subset of neonates with major vulnerability among the whole neonatal population. In fact, VLBW infants show a high incidence of morbitidies and systemic hypotension affects approximately one third of these infants [3]. Therefore, they often require early and careful hemodinamic stabilisation and, as a matter of fact, from 4% to 39% of VLBW infants receive inotropic support [3].Even if at present there are no clear evidences that the treatment of systemic hypotension is beneficial [4,5], such condition is widely and aggressively treated in VLBW infants in order to preserve a proper organ perfusion and an adequate cerebral blood flow [3,4,[6][7][8][9][10][11][12] since hypotension results associated with increased risk of intraventricular haemorrhage and unfavourable neurodevelopmental outcome [13][14][15][16]. Impaired cerebral autoregulation has been dem...