rises with muscle mass, so an adult range over-reads a child
Glucose
3.5–5.5 mmol/L (63–99 mg/dL)
newborn above 2.6 mmol/L
Urine sodium / chloride
under 20 mmol/L means the loss is not renal
a high urine chloride points to the kidney or a diuretic
Liver, bone and metabolic
Measure
Reference
Note
ALT / AST
10–40 / 10–45 U/L
GGT
5–35 U/L
up to 200 in the first months of life
Alkaline phosphatase
child 100–400 U/L, higher in the growth spurt
an adult range makes normal childhood bone turnover look like disease
Bilirubin (total)
under 17 µmol/L (1 mg/dL) beyond the newborn period
Conjugated bilirubin
under 17 µmol/L, or under 20 percent of total
above this is always pathological
Albumin
35–50 g/L
Cholesterol / triglycerides
total cholesterol under 4.4 mmol/L, triglycerides under 1.5 mmol/L
both rise steeply in nephrotic syndrome, in proportion to the albumin loss
Total protein
60–80 g/L
albumin plus globulin – a low total with a low albumin points to loss rather than to synthesis
INR / prothrombin time
INR 0.8–1.2
the earliest measure of failing liver synthesis, and it does not correct with vitamin K once the liver is the problem
Creatine kinase
under 200 U/L
thousands mean muscle: a Duchenne CK runs 10 000 to 20 000 from infancy
Ammonia
newborn under 110, child under 50 µmol/L
Calcium / magnesium / phosphate
2.2–2.7 / 0.7–1.0 / 1.2–2.0 mmol/L
phosphate runs higher in infancy, to about 2.6
Lipase or amylase
three times the upper limit defines pancreatitis
Sweat chloride
under 30 normal, 30–59 intermediate, 60 or more diagnostic
Caeruloplasmin
0.2–0.6 g/L
low in Wilson disease, and it is an acute phase protein, so a normal level during inflammation does not exclude it
Parathyroid hormone
1.6–7.5 pmol/L
rises early in chronic kidney disease, before calcium or phosphate move
Antistreptolysin O titre
under 200 IU/mL in most children
peaks 3–6 weeks after a streptococcal throat infection; a single raised value shows exposure, not active disease
Malaria parasitaemia
any level is abnormal
above 2 percent counts as severe in a non-immune child, and above 10 percent is an indication for exchange transfusion in some protocols
Endocrine and hormones
Measure
Reference
Note
Thyroid stimulating hormone
0.5–5.0 mIU/L beyond the newborn period
it surges to 20 or more in the first days of life, so a newborn screen is read against its own threshold and not against this range
Free T4
12–22 pmol/L
a low free T4 with a high TSH is primary hypothyroidism; a low free T4 with a low or normal TSH points to the pituitary
Cortisol
morning 140–500 nmol/L
the value only means something beside the time and the clinical state: under 100 during hypoglycaemia or shock is inappropriately low
ACTH
2–11 pmol/L (10–50 ng/L)
high with a low cortisol is adrenal failure; high with a high cortisol points above the adrenal
17-hydroxyprogesterone
under 10 nmol/L after the first few days
grossly raised in 21-hydroxylase deficiency, and the newborn screening analyte for congenital adrenal hyperplasia
Growth hormone / IGF-1
a random growth hormone is uninterpretable; peak over 7 µg/L on provocation is normal
IGF-1 is read against age and pubertal stage, and is low in malnutrition as well as in deficiency
LH / FSH
prepubertal under 0.3 IU/L
an LH above 0.3 with a pubertal response to stimulation means the axis has switched on, which is what separates central from peripheral puberty
Testosterone / oestradiol
prepubertal testosterone under 0.5 nmol/L, oestradiol under 20 pmol/L
HbA1c
under 42 mmol/mol (6.0 percent)
48 mmol/mol (6.5 percent) or more is diagnostic of diabetes; it is unreliable when red cell survival is shortened
Insulin / C-peptide
should be undetectable when glucose is low
any measurable insulin during a hypoglycaemic episode is abnormal and is the whole diagnosis in hyperinsulinism
Ketones (blood)
under 0.6 mmol/L
3.0 or more with acidosis defines ketoacidosis; absent ketones during hypoglycaemia is the abnormal finding, not a reassuring one
25-hydroxyvitamin D
sufficient above 50, deficient below 25 nmol/L
this is the storage form and the one to measure; the active 1,25 form can be normal or high in nutritional rickets
Plasma metanephrines
any clear elevation is abnormal
the screening test for a catecholamine-secreting tumour; caffeine and several drugs raise it falsely
Renin / aldosterone
both read against sodium intake and posture
renin rises in salt-losing states and is suppressed when mineralocorticoid excess is driving the blood pressure
Metabolic screening
Measure
Reference
Note
Anion gap
8–16 mmol/L
sodium minus chloride and bicarbonate. Above 16 means an unmeasured acid: lactate, ketones, an organic acid or a toxin
Uric acid
0.12–0.35 mmol/L (2–6 mg/dL) in children
high in tumour lysis, renal failure and several inborn errors; low in molybdenum cofactor deficiency
Plasma phenylalanine
under 120 µmol/L
the newborn screening analyte; treatment is started above about 360 µmol/L and the level guides dietary control
Plasma amino acids / urine organic acids
qualitative
the PATTERN names the disorder rather than any single value, and the sample must be taken during the acute illness to be interpretable
Tumour markers
Marker
Reference
Note
Alpha-fetoprotein
adult and child under 10 ng/mL (under 8 kU/L)
very high at birth and falls to the adult range by about 8 months, so a neonatal value must be read against age; raised in hepatoblastoma, yolk sac tumour and germ cell tumours
Urinary catecholamines
homovanillic and vanillylmandelic acid, reported against urinary creatinine
raised in about nine in ten neuroblastomas, which is why the urine test comes before any biopsy
Immunology and coeliac serology
Measure
Reference
Note
Total IgA
see age note
1–3 years 0.2–1.0, 4–6 years 0.3–1.3, school age 0.5–2.0, adult 0.8–3.0 g/L. Selective IgA deficiency is under 0.07 g/L
IgG / IgM
IgG 5–16 g/L, IgM 0.5–2.0 g/L beyond infancy
IgG falls to a physiological trough at 3–6 months as maternal antibody clears
Tissue transglutaminase IgA
negative under 7 U/mL; 10x the upper limit supports coeliac disease
it is an IgA antibody, so it reads falsely negative when total IgA is low – always check the total IgA beside it
C3 / C4
C3 0.75–1.65 g/L, C4 0.14–0.54 g/L
a low C3 that recovers by 8–12 weeks is post-infectious nephritis; one that stays low beyond that points to C3 glomerulopathy or membranoproliferative disease, and a low C4 alongside it suggests lupus
Cerebrospinal fluid
Measure
Newborn
Child
White cells
0–20 /mm3
0–5 /mm3
Protein
0.4–1.2 g/L
0.15–0.45 g/L
Glucose
at least 60 percent of the blood glucose
at least 60 percent of the blood glucose
Bacterial pattern
hundreds to thousands of neutrophils, high protein, low glucose
same
Case Complete
0 / 0
0%
Score: 0 / 0
Pediatric Case ReviewBoard-Style Questions
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Cardiac Investigation in Children: Choosing the Test in 18 board-style clinical cases with worked explanations. Each case gives you a clinical vignette, four options, the correct answer, and an explanation of why each of the other three is wrong, with the guideline or textbook it follows named on the answer.
Board-style teaching questions for paediatricians and trainees preparing for paediatric board, MRCPCH and licensing examinations. Written from published guidelines and standard paediatric textbooks, with the source named on every answer.
The 18 cases, in order
Most days, for a minute
Every few weeks, without warning
Three times in two years
Normal, and he felt nothing
The button and the notebook
Only when he runs
What the ultrasound only guesses
A number that points, not names
A letter with three initials
Found while looking for something else
Read by the machine
A strip from the ambulance
Pictures over a lifetime
He would not lie down
What would you do differently?
Six weeks, or this afternoon
She read it on the portal
Everything, for completeness
Diagnoses and management options tested
Across the 18 cases you are asked to choose between options such as: A device implanted under the skin, A small device implanted under the skin, It provides evidence that the family complied, By cardiac magnetic resonance, The laboratory must be asked to repeat the analysis, It should be closed at a catheter procedure, As a duplicate of the clinic tracing, Choose, Proceed by holding him still for the pictures, The tests would be uncomfortable.
Clinical pearls from this deck
Choose the monitor by asking how long you would have to wait to catch one episode.
A normal recording with no symptoms during it is a missed window, not a negative test.
The rarer the event, the longer the recorder has to live.
Ask whether the symptom happened during the test before you read the result at all.
Without the diary you have a trace; with it you have a test.
A symptom you can reproduce on demand deserves a provocation test, not another week of waiting.
Work through the deck once for recognition, then again a week later to test yourself — each question gives the answer and explains why every other option fails.
