Tip 145: NEC risk factors

The aetiology of NEC is multifactorial. The most important risk factors include:

  • Prematurity – median gestation of 29/40
  • Low birth weight, especially <1500g (found in 65% of cases in one study)
  • In-utero growth restriction (IUGR)
  • Patent ductus arteriosus (PDA)
  • Formula milk feeds

More recent reviews have focussed on prevention of NEC, e.g. by probiotics.

Reference: Fox T.P., Godavitarne C., (2012). What Really Causes Necrotising Enterocolitis? ISRN Gastroenterology, article ID 628317

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Tip 143: glutaric aciduria type 1

The prevalence is 1:110,000 (EU).

It is an autosomal recessive condition caused by a deficiency of the enzyme glutaryl-CoA dehydrogenase. The screening index metabolite is glutaryl carnitine and the confirmatory test is plasma acylcarnitines, urinary organic acids, 3–OH glutarate and urinary glutaryl carnitine.

External link: National Institute for Health Research, Expanded Newborn Screening Programme

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Tip 142: dobutamine

Dobutamine is a cardio-selective synthetic analogue of isoprenaline. It possesses both inotropic (beta-1 adrenergic stimulation) and chronotropic (beta-2 adrenergic stimulation) properties.

It increases cardiac output by increasing myocardial contractility and stroke volume and causes peripheral vasodilatation. Thus, it is a preferred agent for infants with poor cardiac output, myocardial dysfunction and increased systemic vascular resistance, e.g. HIE.

Reference:  Patwardhan, K. (2009). Inotropes in term neonates. Infant5(1), 12.

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Tip 141: dopamine

Dopamine is a naturally occurring catecholamine precursor of noradrenaline.

Dopamine affects all three major determinants of cardiovascular function (preload, myocardial contractility and afterload). It increases myocardial contractility, heart rate and systemic vascular resistance by stimulation of the alpha and beta receptors. It also exerts renal and endocrine effects which are dose-dependant.

Reference:  Patwardhan, K. (2009). Inotropes in term neonates. Infant5(1), 12.

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Tip 140: cortisol

Very preterm neonates are at increased risk for cortisol insufficiency in acute illness and stress because of immaturity of the adrenal gland.

The adrenal neocortex generally does not synthesize cortisol until ~ 30/40. Before this, the fetus uses progesterone from the placenta to produce cortisol and maternal cortisol crossing the placenta inhibits the fetal hypothalamic-pituitary-adrenal axis.

Low cortisol levels have been associated with hypotension and RDS, hence the logic for using hydrocortisone to treat severe hypotension in very preterm babies.

Reference: Fernandez, E. F., & Watterberg, K. L. (2009). Relative adrenal insufficiency in the preterm and term infant. Journal of Perinatology29, S44-S49.

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Tip 134: MCAD

MCAD (medium chain acyl-CoA dehydrogenase) deficiency is the most common fatty oxidation defect and is inherited in an autosomal recessive fashion.

It became part of the UK newborn screening programme in 2009.

The deficient enzyme is part of the β-oxidation pathway, which is essential at times of fasting stress, thus the need for increased carbohydrate intake or IV dextrose during episodes of illness. Presentation of metabolic decompensation includes hypoketotic hypoglycaemia with lethargy and seizures.

Reference: Dyack, S, Expanded newborn screening: Lessons learned from MCAD deficiency, Paediatr Child Health. Apr 2004; 9(4): 241–243.

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Tip 133: expanded newborn screening programme (UK)

In early 2015, the UK National Screening Committee added an additional four inherited metabolic diseases to the newborn bloodspot screening programme. These are:

  • maple syrup urine disease (MSUD)
  • homocystinuria (pyridoxine unresponsive) (HCU)
  • isovaleric acidaemia (IVA)
  • glutaric aciduria type 1 (GA1)

External links:

National Institute for Health Research, Expanded Newborn Screening Programme

Newborn Blood Spot Screening Programme

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