Why Paediatric Growth Assessment Is Tested
Growth assessment is a core skill in paediatric OSCE stations. It tests your ability to accurately measure and plot growth parameters, interpret centile charts, identify abnormal patterns (failure to thrive, short stature, tall stature), and formulate a differential diagnosis. It frequently appears alongside paediatric history taking or examination stations.
Growth Parameters to Measure
| Parameter | Technique |
|---|---|
| Weight | Scales — nude for infants, light clothing for older children |
| Length (0–2 yrs) | Supine with stadiometer (two-person technique) |
| Height (2+ yrs) | Erect, barefoot, heels together, against wall-mounted stadiometer |
| Head circumference | Measuring tape at widest point (occipito-frontal) — plotted until age 2 |
| BMI | Weight (kg) / Height (m)² — plotted on age-sex-specific centile chart |
💡 Tip
Measure and plot on the correct UK-WHO growth chart: 0–4 years (with WHO standards) and 2–18 years (UK90 standards). Always use the chart appropriate to the child's age, sex, and gestation (corrected age for premature babies until age 2).
Using Centile Charts
- Plot the measurement and draw a vertical line from the child's age — the centile at which the point falls is the child's centile
- 50th centile = median for the UK population
- 2nd–98th centile = normal range (outside = 2 standard deviations from mean)
- Height velocity: the rate of growth — more informative than a single measurement
Red flags on a centile chart:
- Weight or height crossing two or more centile lines downward (or upward)
- Weight significantly below height centile (weight faltering)
- Serial measurements showing deceleration of growth velocity
Mid-Parental Height (MPH)
Adjust expected height for parental heights:
- Boys: (Father's height + Mother's height + 13 cm) ÷ 2
- Girls: (Father's height + Mother's height − 13 cm) ÷ 2
Target centile range: MPH ± 10 cm (covers ~95% of expected heights).
A child growing significantly below their MPH target range requires investigation.
Failure to Thrive (Weight Faltering)
Definition: Weight falling across two or more centile lines, or sustained weight below the 2nd centile, in a child under 2 years.
Causes:
| Category | Examples |
|---|---|
| Inadequate intake | Poor feeding technique, maternal depression, poverty, neglect |
| Malabsorption | Coeliac disease, cystic fibrosis, cow's milk protein allergy |
| Increased requirements | Cardiac disease (CHD), chronic respiratory disease, thyrotoxicosis |
| Organic disease | Renal tubular acidosis, hypothyroidism, metabolic disorders |
⚠️ Red Flag
Always consider non-accidental injury and neglect as a cause of failure to thrive — especially if weight faltering is accompanied by developmental delay or there are safeguarding concerns.
Short Stature — Differentials
| Cause | Features |
|---|---|
| Familial short stature | Normal bone age, height within MPH range, normal velocity |
| Constitutional delay | Delayed bone age, puberty delayed, catch-up expected |
| Growth hormone deficiency | Low height velocity, cherubic appearance, prominent forehead |
| Hypothyroidism | Slow velocity, weight gain, cold intolerance, constipation |
| Turner syndrome (45XO) | Female, webbed neck, broad chest, cardiac/renal anomalies |
| Chronic disease | IBD, renal disease, coeliac, chronic infection |
| Psychosocial deprivation | Catch-up on change of environment |
Investigations
First-line: FBC, ESR, TFTs, bone age (X-ray of left hand and wrist), coeliac screen (IgA + anti-tTG), karyotype (if female). If GH deficiency suspected: IGF-1, IGF-BP3, GH stimulation test.
Frequently Asked Questions
"How do you calculate mid-parental height and why is it important?"
Mid-parental height (MPH) is the expected adult height of a child based on parental heights. For boys: add both parents' heights in cm, add 13 cm, then divide by 2. For girls: add both parents' heights, subtract 13 cm, then divide by 2. The target centile range is MPH ± 10 cm (encompassing approximately 95% of expected heights). MPH is critical in OSCE because it allows you to distinguish constitutional short stature (the child is short but within their genetic potential) from pathological short stature (the child is growing significantly below what their genetics predict). Always ask for parental heights in any growth assessment station.
"What is the difference between constitutional delay in growth and growth hormone deficiency?"
Constitutional delay in growth and puberty (CDGP) is the most common cause of short stature in boys — it represents the normal end of the growth timing spectrum. These children have a delayed bone age (matching their height age rather than chronological age), normal growth velocity, delayed but ultimately normal puberty, and a family history of late puberty. They will reach a normal final adult height, just later than peers. Growth hormone deficiency (GHD), in contrast, is associated with persistently low height velocity (less than 4 cm/year after age 4), a cherubic, immature facial appearance with a prominent forehead, possible micropenis in boys, and other pituitary hormone deficiencies. Bone age may also be delayed but IGF-1, IGF-BP3, and GH stimulation tests will be abnormal.
"What are the causes of failure to thrive and how do you classify them?"
Failure to thrive (weight faltering) is best classified into: inadequate caloric intake (most common) — including poor feeding technique, latch difficulties in breastfeeding, inappropriate feeds, poverty, or neglect; malabsorption — coeliac disease, cystic fibrosis, cow's milk protein allergy, short bowel syndrome; increased caloric requirements — congenital heart disease, bronchopulmonary dysplasia, chronic infections; and primary organic disease — renal tubular acidosis, hypothyroidism, chromosomal disorders, inborn errors of metabolism. In the OSCE, a systematic approach covering all four categories is essential. Always consider safeguarding — neglect and non-accidental injury must be on the differential, particularly when weight faltering is associated with developmental delay or inconsistent parental history.
"How do you plot on a centile chart and what constitutes a red flag?"
To plot on a centile chart: identify the child's age on the horizontal axis and the measurement on the vertical axis, mark the intersection, and note which centile line it falls closest to. For prematurity, use corrected gestational age (chronological age minus weeks premature) until age 2 years. Red flags that require investigation: crossing two or more centile lines downward on any parameter; weight consistently below the 2nd centile; height significantly below the mid-parental height target range; a discrepancy between weight and height centiles (weight much lower than height suggests nutritional cause; height much lower than weight suggests endocrine or skeletal cause); and accelerating weight with faltering height (suggesting hypothyroidism or Cushing's).
"What is Turner syndrome and what growth features should you recognise in an OSCE?"
Turner syndrome (45,XO karyotype) affects approximately 1 in 2000 live female births. Growth features: progressive short stature from birth, typically finishing at 143–144 cm without treatment. Physical features to elicit in history or examination: webbed neck (pterygium colli), broad shield chest with widely spaced nipples, cubitus valgus (increased carrying angle), low posterior hairline, lymphoedema of hands and feet in neonates, and characteristic dysmorphic features. Associated conditions: bicuspid aortic valve and coarctation of the aorta (cardiovascular assessment mandatory), renal anomalies (horseshoe kidney), and primary ovarian failure causing delayed puberty and infertility. Treatment: recombinant growth hormone from early childhood, oestrogen replacement for puberty induction.
"When should you refer a child with short stature to a paediatric endocrinologist?"
Referral is indicated when: height is below the 0.4th centile, height velocity is less than 4 cm/year after age 4 (or less than 6 cm/year under age 4), or the child is growing significantly below their mid-parental height target range. Other indications: growth deceleration crossing centile lines (even from a normal centile), clinical or biochemical features suggesting GH deficiency (low IGF-1, IGF-BP3), features of Turner syndrome, hypothyroidism, or chronic systemic disease, and parental or clinician concern about pubertal progression. In an OSCE, knowing the referral threshold is as important as knowing the differential diagnosis — candidates who can state "I would refer to paediatric endocrinology if height velocity is less than 4 cm/year after age 4" demonstrate clinical decision-making.
Related guides: Paediatric Examination OSCE · Paediatric History Taking OSCE · Paediatric Developmental History OSCE · Neonatal Examination OSCE · Thyroid History OSCE