Chem Path: Paeds clinical chem Flashcards
What are some common problems in low birth weight
Respiratory distress syndrome (RDS) Retinopathy of prematurity (ROP) Intraventricular haemorrhage (IVH) Patent ductus arteriosus (PDA) Necrotising enterocolitis (NEC)
What is NEC
Inflammation of bowel wall leading to necrosis and perforation
bloody stool Abdo distension Pneuomatosis intestinalis (intermural gas)
When do nephrons develop in fetus?
Nephrons develop from about week 6 gestation
When does the foetus start producing urine?
They start producing urine from week 10
When does the Full complement of nephrons start?
36 weeks
Is the GFR in babies high and low and why?
LOW as babies have a high surface area
Why are babies prone to acidosis?
Low GFR - Low amount of Na available for H+ exchange
Short proximal tubule - Low reabsorbive capacity - Absorption of HCO3 is low
Is the threshold for gylcosuria higher or lower than adults in bebes?
Lower
Is the maximum urine osmolality higher or lower than adults for kids and why?
Lower
Kids - 700mmol/Kg
Adults - 12500mmol/Kg
Loop of Henle is short
Distal tubule is unresponsive to aldosterone - what are the consequences?
Persistant Na loss
Reduced K+ excretion
What is the upper normal limit of K+ in adults and kids?
Adults - 5.5
Kids - 6
Why do babies lose weight in the first week of life?
They have a lot of ECF as foetuses. After pulmonary resistance goes down post birth, ANP is released and there is redistribution of ECF.
What should be measured daily in babies born < 30 weeks?
Na due to increased Na demand coupled with Na loss in kidneys
Can you measure Na loss via urine in pre term babies?
NO
When can you give K+ supplement to babies?
Only after a urine sample is achieved (>1mL/kg/hour)
Why is bicarb given to babies and how does it cause electrolyte disturbances?
For acidosis
There is Na in it and their kidneys cannot excrete it
Why is caffeine/theophylline given to babies and how does it cause electrolyte disturbances?
For apnoea
Increases renal Na loss
Why is indomethacin given to babies and how does it cause electrolyte disturbances?
For PDA
Causes oliguria
When is hyperNa common in kids?
In the first 2 weeks of life
What should you consider for hyperNa occurring in kids after 2 weeks of birth?
Salt poisoning
What measurements should you do for salt poisoning?
Urea, creatinine and electrolytes on paired urine and plasma
What happens in congenital adrenal hyperplasia (CAH)
Lack of aldosterone production leading to salt loss and hypoNa
What else happens in CAH?
Hypoglycaemia due to lack of cortisol
What happens to sex steroids in CAH and how does it present?
High levels of pregnenolone
Presents in females with ambiguous genitalia
Growth acceleration
Why is there hyperbilirubinaemia in neonates?
Increased RBC breakdown as foetal Hb gets destroyed
Enhanced enterohepatic circulation - increased reabsorption of bile
What can be a complication of hyperbilirubinaemia?
Kernicterus - Bilirubin that crosses the BBB and has neurological defects
What are the bilirubin levels for exchange transfusion and phototherapy in term babies and pre term babies and why is it lower for pre term babies?
Exchange transfusion - 450 (term) and 230 (preterm)
Phototherapy - 350 (term) and 120 (preterm)
Lower for pre term babies as albumin levels are lower and the BBB is leakier
What are the other causes of hyperbilirubinaemia?
Haemolytic diseases
G6PD deficiency
Crigler-Najjar syndrome - Deficiency of bilirubin conjugation
What is prolonged jaundice?
> 14 days in term babies
>21 days in preterm babies
Why can there be prolonged jaundice in babies?
Prenatal infection / sepsis
Hypothyroidism
Breast milk jaundice
Why can you have conjugated hyperbilirubinaemia?
Biliary atresia Ascending cholangitis with TPN Galactosaemia Alpha 1 anti trypsin Tyrosinaemia 1 Peroxisomal disorders
What happens to calcium levels in babies when they are born?
It falls
Is calcium or phosphate higher in babies?
Phosphate
What happens to babies with hypocalcaemia and low phosphate
Osteopaenia of prematurity
What would see on the CXR of a child with Osteopaenia of prematurity?
Fraying
Splaying
Cupping of long bones
If Osteopaenia of prematurity is left untreated, what can you see?
Flailed chest and respiratory difficulties
What is the biochem of Osteopaenia of prematurity?
Calcium is the last to change
PO4 low
ALP > 1200
How to treat Osteopaenia of prematurity?
PO4 and calcium given separately
OR
1 alpha calcidol
How can rickets present?
Bowed legs, frontal bossing, muscular hypotonia
May get abdominal laxity
Tetany/ hypocalcaemic seizures
Hypocalcaemic cardiomyopathy
How can transient hypophosphataemia be differentiated from rickets?
Very high ALP
electrophoresis
What is pseudo vit D deficiency type 1?
defective renal hydroxylation
Treated with 1,25 OH Vit D
What is pseudo vit D deficiency type 2?
Defective receptor
Treated with 1,25 OH Vit D
What is familial hypoPO4 caused by?
Low tubular maximum reabsoprtion of PO4
Raised urine phosphoethanolamine
