Chem path 7s - Paediatric clinical chemistry Flashcards
What is the earliest gestation which you’d deliver a child?
24 weeks
What are some problems commonly seen in premature babies?
RDS Retinopathy of prematurity IVH PDA NEC
What are the features of NEC?
Bloody stools Abdominal distension Intramural air (pneumatosis intestinalis)
At what gestation do nephrons develop?
6 weeks (full complement of nephrons by 36 weeks)
What gestation do nephrons start producing urine?
10 weeks
At what age is functional maturity of GFR reached?
2 years
Baby kidney anatomy: glomerulus
Large SA: vol ratio therefore relatively low GFR for their SA –> slow excretion of solute load
Limited amount of Na+ available for H+ exchange so more susceptible to acidosis
What are two reasons why neonates are more prone to acidosis?
Limited Na+ available for H+ exchange + reabsorption of bicarbonate is not as effective
Proximal convoluted tubule in neonates
Shorter than adults therefore lower resorptive capability and therefore renal threshold for glycosuria is lower
Loop of Henle/DCT in neonates
Shorter and thus reduced concentrating ability. DCT relatively unresponsive to aldosterone so constantly losing sodium and reduced K+ excretion
What is the upper limit of normal for K+ in neonates?
6.0mmol/L (compared to 5.5. in adults)
How much weight can babies lose in the 1st week of life and be normal?
10% loss of their body weight in 1st week is considered normal
How mcuh more water do neonates need per day than adults?
6x more
Na+ and K+ requirementes in neonates vs adults
Higher
Causes of high insensible water loss in neonates
High SA:volume ratio
Increased resp/metabolic rate
High skin blood flow
High transepidermal fluid loss (skin is not fully keratinised in preterm neonates)
When is hypernatraemia normal in neonates?
Normal in first 2 weeks, suggests dehydration after 2 weeks
Most common cause of hyponatraemia in neonates
CAH - 21-Hydroxylase deficiency
In a prem baby, why are the thresholds to treat hyperbilirubinaemia lower?
They have less albumin and a leakier BBB
What is NICE’s definition of prolonged jaundice?
Jaundice >14 days in a term baby or >21 days in prem baby
a conjugated bilirubin level above what threshold is always pathological in neonates?
> 20umol/L
What are some causes of raised conjugated bilirubin?
Biliary atresia
Choledochal cyst
Ascending cholangitis from TPN, inherited metabolic diseases
Which 4 inherited metabolic diseases cause a conjugated hyperbilirubinaemia?
Galactosaemia
Alpha-1-antitryptase deficiency
Tyrosinaemia 1
Peroxisomal diseases
Investigations in galactosaemia
RBC Gal-1- PUT
Investigations in alpha-1-antitryptase deficiency
Alpha-1-antitryptase
