Paediatric chemistry

Question 1

What common problems occur with low birth weight (5)

Answer 1

Respiratory distress syndrome

Retinopathy of prematurity

Intraventricular haemorrhage

Patent ductus arteriosus

Necrotizing enterocolitis – necrosis and perforation

Question 2

What is renal function like in children?

Answer 2

Basically a reduced version of an adult

• Low GFR for surface area
• Less reabsorption due to short pct
• Reduced concentrating ability due to short loops of henle and DCT
• Persistent sodium loss due to distal tubule being a bit aldosterone insensitive

Question 3

When does the GFR mature in children

Answer 3

by age 2

Question 4

Why is there higher water loss in children?

Answer 4

• High surface area to body weight ratio
• Skin blood flow is increased
• Metabolic/respiratory rate is higher than adults
• Trans epidermal fluid loss (skin less of a good barrier as it’s immature)

Question 5

What electrolyte disturbance is common in the first 2 weeks of life,

Answer 5

Hypernatraemia is common in the first 2 weeks of life, although can be a marker of
dehydration or an overly concentrated milk formula

Question 6

What may cause hypontraemia in the first 5 days of life ?

Answer 6

Excess total body water usually due to excessive intake.

• Rarely may be SIADH secondary to infection (pneumonia/meningitis) or
  intraventricular haemorrhage

Question 7

What may cause hypontraemia after the 5 days of life ?

Answer 7

Usually loss of sodium loss due to immature tubular function in patients on
diuresis

• Factitious (i.e. Na+ normal but appears low) e.g. hyperglycaemia
• Congenital adrenal hyperplasia – 21 alpha hydroxylase deficiency
• Addisonian presentation
• Usually identified on Guthrie spot

Question 8

Pathological jaundice cause in the 1st 24 hours of life?

Answer 8

(acute haemolysis or sepsis)

Question 9

Pathological jaundice cause after 2 weeks of life?

Answer 9

(hepatobiliary failure)