Turner syndrome is one of the most commonly delayed diagnoses in the UK — the average age of diagnosis is 15 years in girls identified during routine medical encounters, compared to approximately 9 years for girls identified incidentally (e.g., through chromosomal analysis for another reason). Turner syndrome (45,X or mosaic variants) affects approximately 1 in 2,000 girls and presents with: short stature (main presenting complaint in 70%), primary amenorrhoea, webbed neck, wide carrying angle (cubitus valgus), broad chest with widely spaced nipples, and cardiovascular abnormalities (aortic coarctation — present in ~30% — and bicuspid aortic valve). The diagnosis is frequently delayed because: (1) girls with Turner's may have relatively normal height in childhood (short stature may only become apparent in adolescence when the pubertal growth spurt fails to occur); (2) the distinctive physical features are subtle and not reliably identified without systematic examination; (3) physicians may wait for amenorrhoea before investigating, by which time the girl is in her mid-teens. Any girl who is consistently below the 2nd centile for height without a clear familial explanation, or who has any two of the characteristic features, should have a karyotype performed. Growth hormone therapy (Norditropin, Omnitrope) significantly improves final adult height in Turner syndrome and must be started before epiphyseal fusion (typically by age 12) to achieve maximum benefit.

Coeliac disease is the most common systemic cause of unexplained short stature in UK children — it is estimated that approximately 30–40% of coeliac children present without gastrointestinal symptoms (silent coeliac disease), with short stature, iron-deficiency anaemia, or fatigue as the sole presenting features. Anti-tissue transglutaminase IgA (anti-tTG IgA) combined with total serum IgA (to exclude IgA deficiency, which causes false-negative anti-tTG) is the recommended first-line screening test per NICE NG20. The test should be performed on a normal gluten-containing diet (the antibody disappears within weeks of starting a gluten-free diet, making the test falsely negative if gluten has been restricted). GPs encountering any child with unexplained short stature, growth faltering, or iron-deficiency anaemia should routinely screen for coeliac disease with anti-tTG IgA + total IgA. A positive test requires duodenal biopsy for confirmation (paediatric gastroenterology), but a strongly positive result in a symptomatic child is highly predictive. After diagnosis and dietary treatment, catch-up growth of 1–2 centile channels is typical within 12 months of starting a strict gluten-free diet.

Bone age X-ray (left hand and wrist radiograph assessed by a paediatric radiologist using the Greulich and Pyle atlas or TW2 method) is one of the most useful investigations in short stature assessment — it compares the child's skeletal maturation to their chronological age. The findings guide interpretation: (1) Bone age significantly delayed vs chronological age (e.g., 10-year-old child with bone age of 7–8 years) = constitutional delay of growth and puberty (CDGP) OR systemic disease OR hypothyroidism — the delayed bone age means the child has significant growth potential still remaining and is expected to reach a normal adult height, but puberty will come late; (2) Bone age approximately equal to chronological age with short stature = the child's skeleton is aging at the expected rate but at a lower height — likely familial short stature, less growth potential remaining, or endocrine cause; (3) Advanced bone age (older than chronological age) in a short child = concerning for early puberty with premature epiphyseal fusion, or chronic glucocorticoid use. The bone age X-ray is arranged via radiology and is an appropriate primary care investigation before paediatric referral — it directly informs the referral letter and guides the specialist consultation.

Turner syndrome karyotyping in all girls with unexplained short stature is a NICE recommendation — the karyotype (chromosomal analysis from a blood sample) takes approximately 2–3 weeks and definitively identifies 45,X or mosaic Turner syndrome. The test should be requested by the GP in the investigation phase rather than waiting for the paediatric referral, as it provides information that directly informs the referral and expedites specialist management. The clinical implication of the delayed Turner diagnosis is significant: growth hormone therapy (licensed for Turner syndrome in girls — NICE TA188) is most effective when started early (before age 12, before epiphyseal fusion is advanced). Each year of delay in starting GH therapy represents approximately 1 cm of final adult height lost. GPs who identify Turner syndrome on karyotyping should urgently refer to paediatric endocrinology, arrange echocardiogram (aortic coarctation screen), and renal USS (renal anomalies in ~30% of Turner syndrome).

GH therapy eligibility (NICE TA188) requires all of: height standard deviation score (SDS) below −2.5 (below the 0.6th centile), growth velocity at or below the 25th centile for age (or <2 cm/year), and GH deficiency confirmed by suboptimal response to GH stimulation test (peak GH <20 mU/L — modern cutoff). GH is also licensed (not through GH deficiency criteria) for: Turner syndrome, Prader-Willi syndrome, SHOX gene deficiency, chronic kidney disease pre-transplant, and SGA (small for gestational age) if not showing catch-up growth by age 4. GP role in GH therapy: continuation prescribing once specialist has initiated, injection site rotation advice (lipoatrophy prevention), 3-monthly growth measurement and plotting, and monitoring for side effects (benign intracranial hypertension — papilloedema, headache — and hip pain suggesting slipped capital femoral epiphysis — SCFE, which is more common with GH therapy).

The psychological impact of constitutional delay of growth and puberty (CDGP) in adolescent boys is frequently underestimated — a 14-year-old boy who is significantly shorter than all his peers and has not yet begun puberty experiences profound social difficulties: exclusion from sport teams, bullying, difficulties with romantic relationships, and severe self-esteem damage. Parents (particularly fathers who experienced CDGP themselves) are often dismissive: 'I was the same at his age and I turned out fine.' While CDGP has an excellent ultimate prognosis (normal adult height and fertility), the psychological harm during the years of delayed development is real. NICE and the Society for Endocrinology recommend that treatment to advance puberty (testosterone esters in boys — Sustanon 50–100 mg IM monthly × 3–6 months) is appropriate when severe psychological distress is present, particularly when bone age is sufficiently delayed that a short course will not compromise final adult height. This treatment decision should be made in consultation with paediatric endocrinology, but GPs should raise the option with families rather than waiting passively.

The IGF-1 monitoring principle for GH therapy reflects the pharmacological mechanism — GH does not act directly on the growth plate but stimulates hepatic production of IGF-1 (insulin-like growth factor 1), which then acts on chondrocytes to promote longitudinal bone growth. IGF-1 levels therefore reflect GH action at the tissue level and are the preferred biomarker for GH therapy monitoring. The target: age- and sex-matched IGF-1 in the mid-normal range (approximately 0 to +2 SDS). Supranormal IGF-1 (>+2 SDS) suggests over-treatment and should trigger dose reduction (long-term supranormal IGF-1 is associated with increased cancer risk — this is the principal long-term safety concern with GH therapy). Sub-normal IGF-1 suggests under-dosing or poor compliance. The GP monitoring role in shared care: annual IGF-1, annual HbA1c (GH is insulin-antagonistic and can unmask pre-diabetes in susceptible individuals), and growth measurement every 3–6 months.

The Child Growth Foundation (CGF) is a UK charity that provides excellent patient information on all aspects of growth disorders — their website (childgrowthfoundation.org) has condition-specific information sheets for parents and young people covering Turner syndrome, GH deficiency, CDGP, and skeletal dysplasias, written in accessible language. GPs should routinely signpost families dealing with growth concerns to the CGF as a trusted resource. The Turner Syndrome Support Society (tsss.org.uk) is a condition-specific charity providing peer support, information on current management standards, and advocacy for appropriate investigation and treatment timelines. GPs who identify Turner syndrome should provide the family with these resources at the same consultation as the diagnosis discussion.

Slipped capital femoral epiphysis (SCFE) is a specific complication of GH therapy that GPs in shared care must know — GH therapy increases growth rate, which temporarily increases the shear stress on the growth plate of the femoral head. In susceptible children (particularly obese, or those with GH deficiency who are growing rapidly with treatment), the femoral head can slip off the femoral neck at the growth plate. Clinical presentation: limp + hip pain (sometimes referred to the knee) in a child on GH therapy. The risk period is during the first 6–12 months of GH therapy when growth rate is fastest. Action: stop GH therapy immediately + same-day orthopaedics (urgent surgical pinning prevents further displacement and avascular necrosis). GPs managing children on GH therapy should document this safety net explicitly at each review and ensure the family knows to report any new hip or knee pain immediately.