paediatric clinical chemistry Flashcards
what are some common causes of problems in neonates with Low birth weight ?
Respiratory distress syndrome (RDS) ((Retinopathy of prematurity (ROP))
Intraventricular hemorrhage (IVH)
Patent ductus arteriosus (PDA)
Necrotizing enterocolitis (NEC)
how does necrotising enterocolitis present?
Inflammation of the bowel wall progressing to necrosis and perforation
Bloody stools
Abdominal distension
Xray will show Intramural air
when does full maturity of glomerular and tubular function occur?
glomerular - 2 years old
tubular - even longer
how does renal structure and function differ in neonates?
Low GFR for surface area
Short proximal tubule means there is a lower reabsorptive capability than in the adult although:
Loops of Henle/distal collecting ducts are short and juxtaglomerular - less ability to concentrate urine
Distal tubule is relatively unresponsive to aldosterone: -> more Na loss, less K+ loss.
what is the total body water in prem neonates, term neonate, adult?
prem neonate - 80%
term neonate - 75% so all babiees lose weight in their first week after birth. they should regain after day 7
adult - 60%
what is a neonates requireement for sodium, water and potassium?
they need:
6x more water
3.5x more sodium
2x more potassium
why is a preemature neonate <30wks not to be given potassium supplement immediately?
when to be given it?
can cause hypernatraemia
wait till they produce a urine output of > 1 ml/kg/hr first.
which drugs are not to be given to a premature neonate <30wks and why?
§ Bicarbonate for acidosis - contains high Na+
§ Antibiotics (usually sodium salts)
§ Caffeine/theophylline (for apnoea) - increases renal sodium losses
§ Indomethacin (for PDA) - causes oliguria
what is a likeely cause of hyponatraemia in neonates?
Congenital adrenal hyperplasia (CAH):
Most commonly caused by deficiency of 21-hydroxylase
This leads to reduced cortisol and aldosterone which leads to salt loss
what are the clinical features of Congenital adrenal hyperplasia (CAH)
§ Hyponatraemia/hyperkalaemia with volume depletion
§ Hypoglycaemia (due to lack of cortisol)
§ Ambiguous genitalia in female neonates
□ This is not an obvious feature in male neonates (they may present with a salt-losing crisis)
§ Growth acceleration
what are the Reasons for and aetiology of Neonatal Hyperbilirubinaemia?
Aetiology:
Haemolytic disease (ABO, rhesus etc)
G-6-PD deficiency
Crigler-Najjar syndrome
Reasons:
○ High level of bilirubin synthesis
○ Low rate of transport into the liver
○ Enhanced enterohepatic circulation
• IMPORTANT: the bilirubin is unconjugated
why is hyperbilirubinaemia an issue?
free bilirubin causes Kernicterus (bilirubin encephalotpathy) - after crossing blood brain barrier
how is hyperbilirubinaemia treated?
Depends on albumin levels - used to set thresholds
becuase albumin binds to bilirubin
threshold lower in preterm babies due to less albumin
options:
○ No treatment
○ Phototherapy
○ Exchange transfusion
what are the causes of prolonged jaundice in neonates?
§ Prenatal infection/sepsis/hepatitis
§ Hypothyroidism
§ Breast milk jaundice
in conjugated Hyperbilirubinaemia, what counts as a pathological Conjugated bilirubin?
> 20 µmol/L is ALWAYS pathological
