Paeds - The unconscious baby Flashcards
What conditions does the Newborn Blood Spot (NBS) screening programme, screen for? (9)
4-9 are inherited metabolic diseases (6 in total)
- Sickle cell disease
- Cystic Fibrosis
- Congenital hypothyroidism
- Phenylketonuria
- MCADD (medium-chain acyl-CoA dehydrogenase deficiency)
- Maple syrup urine disease (MSUD)
- Isovaleric acidaemia
- Glutaric aciduria type 1
- Homocystinuria
Does being afebrile exclude sepsis in babies?
No!!
Babies may have hypothermia or temp instability when septic
What effects can raised ammonia have?
Respiratory:
- Respiratory stimulant –> tachypnoea
Neuro:
- Altered consciousness (neurotoxic)
- Hyperammonemia is a feature of hepatic encephalopathy
What are the normal serum ranges for ammonia in 1) neonates, 2) children?
Serum ammonia:
- Neonates < 100 micromols/L
- Children < 50 micromols/L
How is an anion gap calculated?
(sodium + potassium) - (bicarbonate + chloride)
(Na+ + K+) - (HCO3- + Cl-)
Normal anion gap = 8-14 mmol/L
What are the causes of High anion-gap metabolic acidosis?
CAT MUDPILES
- C - carbon monoxide, cyanide, congenital HF
- A - aminoglycosides Abx (e.g. gentamicin, neomycin)
- T - theophylline
- M - methanol
- U - uraemia (renal failure)
- D - diabetic ketoacidosis, alcohol ketoacidosis
- P - paracetamol (chronic use)
- I - iron, inborn errors of metabolism, isoniazid (abx for TB)
- L - lactic acidosis (shock, sepsis, hypoxia)
- E - ethenal (due to lactic acidosis), ethylene glycol (anti-freeze)
- S - salicylates (e.g. Aspirin)
What are the 2 main groups of inborn errors of metabolism causing hyperammonaemia?
-
Urea cycle disorders:
- classically large hyperammonaemia i.e. > 1000 micromols/L (markedly raised) - but can be normal in milder cases
- liver dysfunction present
- blood gas - respiratory alkalosis (ammonia = respiratory stimulant –> lower blood CO2)
-
Organic acidaemias:
- hyperammonaemia < in urea cycle defects
- blood gas - metabolic acidosis + hyperammonaemia
- metabolic acidosis that doesn’t respond to fluid resuscitation
- raised anion gap
- two most common organic acidaemias:
- Methylmalonic acidaemia
- Propionic acidaemia
What causes a normal anion-gap metabolic acidosis or hyperchloraemic metabolic acidosis?
-
GI bicarbonate loss:
- diarrhoea
- fistula e.g. intestinal, pancreatic, biliary
- ureterosigmoidostomy - surgery to connect ureters to sigmoid colon (in bladder cancer when bladder is removed)
- Renal tubular acidosis
- Addison’s disease (hypoaldosteronism)
- Drugs:
- acetazolamide (carbonic anhydrase inhibitor) - used in glaucoma and epilepsy
- trimethoprim (abx) - UTI’s and RTIs
- cyclosporin
- potassium sparing diuretics e.g. spironolactone
- ammonium chloride injection
What is Phenylketonuria (PKU)?
An autosomal recessive condition caused by a disorder of phenylalanine metabolism
- 1 in 10,000 births
- Lack of phenylalanine hydroxylase - an enzyme required to convert phenylalanine to tyrosine - thus increase in phenylalanine levels
Features:
- Presents by 6-months
- Severe developmental delay –> thenregression, where there is decline in current developmental skills
- Seizures - typically infantile spasms
- Eczema
- ‘musty’ odour to urine & sweat
- tend to have fair hair
How is Phenylketonuria (PKU) managed?
- Low protein diet - phenylalanine comes purely from diet (not produced in body)
- Amino acid supplements - all AA’s apart from phenylalanine
- Blood monitoring - ensure phenylalanine isn’t too high but also not too low, as it is needed for protein synthesis
What is the prognosis for Phenylketonuria?
Good!!
- With good dietary control, people lead normal lives
- Some even come off diet with no consequences as adults as it is the developing brain that is most vulnerable to high phenylalanine
How is PKU diagnosed?
Guthrie test = ‘heel-prick’ test done at 5-9 days of life
(Newborn / neonatal blood spot)
- hyperphenylalaninaemia
- phenylpyruvic acid in urine
Which organisms commonly causes sepsis / severe infection in neonates?
Group B streptococcus
Also common in:
- Pregnancy
- Diabetes
- Immunocompromised
- Elderly
Is group b streptococcus gram +ve or -ve?
Gram +ve
How is a group B strep infection managed in a neonate?
- Supportive therapies (varies depending on severity and manifestation of infection)
- Antibiotics:
- 1st line:
- benzylpenicillin + gentamicin
- If infant > 1-month –> cefotaxime
- 2nd-line:
- vancomycin (if penicillin allergy) (+ gentimicin if meningitis)
- 1st line:
