📋 Key Information Summary
- Turner syndrome (TS) affects approximately 1 in 2500 live-born females and is characterised by complete or partial loss of the second X chromosome.
- Karyotype is the gold standard for diagnosis; mosaicism (45,X/46,XX) occurs in ~30% of cases and may present later with milder features.
- Short stature is near-universal and responsive to recombinant growth hormone (somatropin), which can add 5–8 cm to final adult height when commenced in early childhood.
- Gonadal dysgenesis with streak ovaries leads to hypergonadotropic hypogonadism in >90%; oestrogen replacement therapy (ORT) is essential from age 11–12 years to induce puberty and maintain bone health.
- Bicuspid aortic valve (BAV) occurs in ~30% and coarctation of the aorta in ~10%; lifelong cardiac surveillance every 5–10 years is mandatory.
- Aortic dissection risk is 6× general female population; blood pressure must be controlled to <130/80 mmHg and competitive sport restrictions may apply if aortic root dilation >2.5 cm/m² is present.
- Autoimmune thyroid disease (Hashimoto's thyroiditis) occurs in ~30%; annual TSH and anti-TPO antibodies from age 4 years is recommended.
- Renal anomalies (horseshoe kidney, duplex collecting system) are present in ~30% and warrant baseline renal ultrasound.
- Sensorineural hearing loss develops in up to 70% by adulthood; audiology assessment every 3–5 years is required.
- Fertility is possible in ~2% with spontaneous puberty; oocyte cryopreservation and IVF with donor oocytes are options but carry high-risk pregnancy considerations including aortic dissection.
- Transition of care from paediatric to adult endocrinology should occur by age 16–18 with a structured multidisciplinary plan.
- Psychosocial support, educational assessment for non-verbal learning difficulties, and screening for anxiety and depression are integral to holistic management.
🎧 Audio Brief
Introduction & Australian Epidemiology
Turner syndrome (TS) is a chromosomal condition affecting phenotypic females, resulting from complete or partial monosomy of the X chromosome. First described by Henry Turner in 1938, it is one of the most common chromosomal abnormalities in females and carries significant implications across multiple organ systems throughout the lifespan.
In Australia, TS occurs in approximately 1 in 2500 live-born female infants, equating to roughly 10–15 new diagnoses per year nationally. However, the true prevalence may be higher as up to 99% of 45,X conceptions are lost spontaneously in utero, and mosaicism (45,X/46,XX) can present subtly in adolescence or adulthood. The Australian Institute of Health and Welfare (AIHW) records TS as part of congenital anomaly surveillance, and the condition receives ongoing attention through state-based genetics services and paediatric endocrinology networks.
TS requires lifelong, multidisciplinary care spanning paediatric and adult endocrinology, cardiology, audiology, reproductive medicine, psychology, and renal medicine. Early diagnosis enables timely intervention for growth, puberty induction, and cardiovascular risk mitigation. This guideline provides an evidence-based framework for the diagnosis and management of TS in the Australian healthcare setting.
Genetics & Pathophysiology
Chromosomal Basis
TS arises from the loss of all or part of one X chromosome in phenotypic females. The karyotypic spectrum includes:
| Karyotype | Frequency | Clinical Notes |
|---|---|---|
| 45,X (complete monosomy) | ~45% | Most severe phenotype; usually diagnosed prenatally or in infancy |
| 45,X/46,XX (mosaicism) | ~30% | Variable phenotype; may have spontaneous puberty; diagnosed later |
| 46,X,i(Xq) | ~15% | Isochromosome Xq; risk of autoimmune disease and hearing loss |
| 46,X,del(Xp) | ~5% | Short stature gene (SHOX) lost from Xp; milder gonadal failure |
| 46,X,r(X) | ~5% | Ring chromosome; phenotype depends on XIST expression |
Pathophysiological Mechanisms
- SHOX haploinsufficiency: The SHOX gene (Short Stature Homeobox) on Xp22.33 escapes X-inactivation. Loss of one copy leads to impaired long-bone growth, accounting for the short stature characteristic of TS. This is the primary target for growth hormone therapy.
- Ovarian dysgenesis: Accelerated oocyte atresia results in streak ovaries by childhood or adolescence in most patients with 45,X. This leads to oestrogen and progesterone deficiency, absent puberty, and primary amenorrhoea.
- Lymphatic maldevelopment: Impaired lymphatic drainage in utero underpins nuchal cystic hygroma, peripheral lymphoedema, and contributes to left-sided cardiac anomalies including coarctation and BAV.
- Cardiovascular embryopathy: Abnormal endocardial cushion development results in BAV (~30%), coarctation of the aorta (~10%), and aortic root dilation predisposing to dissection.
- Epigenetic effects: Imprinting and X-inactivation patterns in mosaic individuals influence phenotypic variability. Skewed X-inactivation may modulate severity.
Counselling note: TS is almost always a de novo event; recurrence risk for parents of an affected child is <1%. However, mosaic mothers with TS who conceive have a slightly increased risk of chromosomal abnormalities in offspring. Pre-conception genetic counselling is recommended.
Clinical Features
The clinical presentation of TS varies by age, karyotype, and degree of mosaicism. Features may be detected antenatally, at birth, in childhood, or in adolescence/adulthood.
Antenatal & Neonatal Features
- Increased nuchal translucency or cystic hygroma on antenatal ultrasound
- Left-sided cardiac anomaly (coarctation, hypoplastic left heart) on foetal echocardiography
- Non-immune hydrops foetalis
- Low birth weight and short length for gestational age
- Peripheral lymphoedema of hands and feet (puffy hands/feet)
- Webbed neck (pterygium colli) from resolving cystic hygroma
- Low posterior hairline
- Shield chest with widely spaced hypoplastic nipples
Childhood Features
- Short stature — most common presenting feature; height velocity falls below the 25th centile from age 2–3 years
- Cubitus valgus (increased carrying angle)
- Short fourth metacarpal
- Multiple pigmented naevi
- Nail dysplasia (hyperconvex nails)
- Recurrent otitis media (common in early childhood)
- Feeding difficulties and failure to thrive in infancy
Adolescent & Adult Features
- Delayed puberty or primary amenorrhoea (absent breast development by age 13)
- Primary ovarian insufficiency (hypergonadotropic hypogonadism)
- Sensorineural hearing loss (high-frequency; progressive from age ~10 years)
- Autoimmune thyroiditis (hypothyroidism most common)
- Coeliac disease (prevalence ~4–6%)
- Hypertension (often from coarctation or essential)
- Aortic root dilation and risk of dissection
- Osteoporosis (oestrogen-dependent bone mineral accrual impaired)
- Non-verbal learning difficulties, executive function impairment
- Anxiety and depression (increased prevalence)
- Hepatic steatosis and abnormal LFTs
- Metabolic syndrome and type 2 diabetes mellitus (increased risk)
Features by Organ System
| System | Feature | Prevalence |
|---|---|---|
| Cardiovascular | Bicuspid aortic valve | ~30% |
| Coarctation of the aorta | ~10% | |
| Aortic root dilation | ~20–30% | |
| Renal | Horseshoe kidney | ~10% |
| Duplex collecting system | ~15% | |
| Endocrine | Hashimoto's thyroiditis | ~30% |
| Coeliac disease | 4–6% | |
| ENT/Audiology | Sensorineural hearing loss | up to 70% (adults) |
| Skeletal | Osteoporosis | ~25–50% |
| Psychosocial | Non-verbal learning difficulty | ~30–40% |
Investigations & Diagnosis
Diagnostic Approach
Diagnosis requires a high index of clinical suspicion. Karyotype analysis on peripheral blood lymphocytes (≥30 cells counted) is the gold standard. Diagnosis may be made prenatally (via amniocentesis or CVS for abnormal ultrasound findings), at birth, in childhood (short stature), or in adolescence (delayed puberty).
Diagnostic delay: Studies show the median age of diagnosis in Australia is 6–8 years for classic 45,X but can be as late as 15 years for mosaic 45,X/46,XX. Height below the 2nd centile or crossing centiles downward in a female child should prompt karyotype analysis.
Baseline Investigations at Diagnosis
Essential
Peripheral blood karyotype (≥30 cells)
Gold standard. If mosaic, consider skin biopsy fibroblast karyotype. MBS Item 73287 (chromosome study).
Essential
Echocardiography
Assess for BAV, coarctation, aortic root dilation (measure sinuses of Valsalva). Repeat at diagnosis, then as per cardiology schedule.
Essential
Renal ultrasound
Screen for horseshoe kidney, duplex system, rotational anomalies.
Essential
Thyroid function (TSH, fT4) + anti-TPO antibodies
Screen for Hashimoto's thyroiditis. Annual monitoring recommended.
Essential
Coeliac serology (tTG-IgA, total IgA)
Screen at diagnosis and if symptoms develop. MBS Item 69542.
Available
Audiology assessment (pure tone audiometry)
Baseline at age 4–6 years; repeat every 3–5 years. Bulk-billed under Medicare for paediatric patients.
Available
Bone age (left wrist X-ray)
For growth assessment. Compare chronological and bone age; delayed bone age supports GH therapy initiation.
Available
Liver function tests (LFTs)
Baseline hepatic assessment. Abnormalities (GGT, ALP) are common and should be monitored.
Available
Fasting lipids and glucose/HbA1c
Metabolic risk screening from age 10 years.
Available
DXA scan (bone densitometry)
Baseline in late adolescence or when oestrogen deficiency confirmed. MBS Item 12322.
Referral
MRI brain (if indicated)
If concern for intracranial anomalies (e.g., Chiari malformation in ring X chromosomes). Specialist request.
Available
Lipid profile
Cardiovascular risk assessment. Repeat every 2–5 years from age 10.
Differential Diagnosis
- Constitutional short stature / familial short stature
- Growth hormone deficiency (isolated)
- Noonan syndrome (46,XX or 46,XY; autosomal dominant; PTPN11 mutation)
- SHOX-related short stature (Léri-Weill dyschondrosteosis)
- 46,XY gonadal dysgenesis (Swyer syndrome) — if streak gonads but normal height
- Pure gonadal dysgenesis (46,XX)
Management
Management of TS is lifelong and multidisciplinary. Core pillars include growth hormone therapy, pubertal induction, cardiovascular surveillance, management of associated autoimmune and metabolic conditions, and psychosocial support.
1. Growth Hormone Therapy
Recombinant human growth hormone (somatropin) is the standard of care for short stature in TS and is PBS-subsidised under the Life Saving Drugs Program (LSDP) or as Authority Required for this indication.
Somatropin
Norditropin® · NutropinAq® · Growth hormone analogue
Indication
Short stature in Turner syndrome
Dose
0.045–0.050 mg/kg/day SC once daily (evening)
Paediatric dose
0.045–0.050 mg/kg/day SC; adjust by weight as child grows
Route
Subcutaneous injection
Initiation
From age 4–6 years or when height falls below 5th centile
Duration
Continue until bone age ≥14 years or growth velocity <2 cm/year
Expected benefit
5–8 cm gain in final adult height; earlier initiation = greater benefit
Monitoring
Height velocity q3–6 months; IGF-1 annually (target <2 SD above mean); glucose/HbA1c annually
PBS status
Authority Required — LSDP
Combination therapy: Low-dose oxandrolone (0.03 mg/kg/day) may be added to GH in adolescents >10 years to augment height velocity. Oxandrolone is not PBS-listed for this indication in Australia and requires Specialist (derogation) authority. Monitor for virilisation and hepatic effects.
2. Pubertal Induction & Oestrogen Replacement
Oestrogen replacement therapy (ORT) is essential for inducing secondary sexual characteristics, promoting uterine growth, achieving peak bone mass, and optimising quality of life. Pubertal induction should commence at age 11–12 years (or when clinically appropriate to match peers).
17β-Oestradiol (transdermal)
Estraderm® · Climara® · Transdermal patch
Initial dose
3.1–6.2 µg/day patch (or 0.2 mg oral oestradiol) — very low dose
Titration
Double dose every 6 months over 2–3 years to adult dose (50–100 µg/day patch)
Route
Transdermal (preferred) or oral
Progesterone addition
Add cyclic oral progesterone (medroxyprogesterone 5–10 mg/day for 10–12 days/cycle) or Mirena IUS once breakthrough bleeding occurs or after 2 years of oestrogen
Duration
Lifelong until at least age 50 (average menopause age)
PBS status
✔ PBS General Benefit
Medroxyprogesterone acetate
Provera® · Progestogen
Dose
5–10 mg PO daily for 10–12 days per calendar month
Indication
Endometrial protection once oestrogen established
PBS status
✔ PBS General Benefit
Transdermal vs oral oestrogen: Transdermal 17β-oestradiol is preferred in adolescents as it avoids first-pass hepatic metabolism, provides more physiological hormone levels, has a lower thrombotic risk, and is associated with better IGF-1 profiles during concurrent GH therapy.
3. Cardiovascular Surveillance & Management
Cardiovascular disease is the leading cause of premature mortality in TS, primarily from aortic dissection and ischaemic heart disease. A structured surveillance programme is essential.
At diagnosis
Transthoracic echocardiography (TTE) — assess aortic valve morphology, coarctation, aortic root dimensions (sinuses of Valsalva). Refer to paediatric/adult congenital cardiology.
Every 5 years (low risk)
Repeat TTE if normal initial study and no BAV or hypertension. MRI aorta preferred from age 12 years.
Every 1–2 years (high risk)
If BAV, coarctation, aortic dilation, or hypertension present. Cardiac MRI preferred for accurate aortic measurements.
Pregnancy
Pre-pregnancy cardiac MRI with aortic measurements. Aortic root >2.5 cm/m² = high-risk pregnancy requiring tertiary centre care.
Blood pressure management: Target <130/80 mmHg. ACE inhibitors (enalapril, perindopril) or angiotensin receptor blockers (losartan) are preferred agents, particularly if aortic dilation is present. Beta-blockers may be added if needed.
Aortic dissection risk: Risk is approximately 6× the general female population. Risk factors include BAV, hypertension, aortic coarctation (repaired or unrepaired), and aortic root dilation. Patients with aortic root >2.5 cm/m² should avoid high-intensity competitive and contact sport. Urgent investigation (CT aortogram) for acute chest/back pain.
4. Thyroid Disease Management
Hashimoto's thyroiditis is the most common autoimmune condition in TS (~30%). Annual TSH and fT4 monitoring from age 4 years is recommended. If hypothyroidism develops:
Levothyroxine
Oroxine® · Eutroxsig® · Thyroid hormone replacement
Dose
1.6 µg/kg/day PO (paediatric); 50–100 µg/day PO (adult) — titrate to TSH
Administration
Fasting, 30–60 min before food. Separate from calcium/iron by 4 hours.
Monitoring
TSH every 6–12 months; adjust dose during GH therapy and puberty
PBS status
✔ PBS General Benefit
5. Fertility & Reproductive Counselling
Approximately 2–5% of women with TS achieve spontaneous conception, predominantly those with mosaic karyotypes who undergo spontaneous puberty. Fertility options include:
- Spontaneous conception: Possible in mosaic patients. Pregnancy must be managed in a tertiary centre due to aortic dissection risk (1–2% per pregnancy).
- Oocyte cryopreservation: May be considered in adolescents/adults with evidence of ovarian reserve (antral follicle count, AMH). Requires IVF referral.
- IVF with donor oocytes: Most common route to pregnancy in TS. Requires oestrogen priming of the uterus.
- Surrogacy: Legal option in some Australian states (varies by jurisdiction).
Pregnancy in TS is high-risk: All pregnancies should be managed at a tertiary centre with maternal–foetal medicine and cardiology input. Pre-pregnancy cardiac MRI, echocardiography, and blood pressure optimisation are mandatory. Risk of aortic dissection is highest in the third trimester and immediate postpartum.
6. Bone Health
Osteoporosis risk is increased due to oestrogen deficiency, SHOX haploinsufficiency, and possibly intrinsic bone abnormalities. Management includes:
- Adequate calcium intake (1000–1300 mg/day) and vitamin D supplementation (1000–2000 IU/day if 25-OH vitamin D <75 nmol/L)
- Lifelong oestrogen replacement to maintain bone mineral density
- Weight-bearing exercise
- DXA scan at age 18–20 and then every 2–5 years, or earlier if oestrogen non-compliance
- Consider bisphosphonates (alendronate) if established osteoporosis (T-score <−2.5) — PBS Authority Required
7. Coeliac Disease
Screen with tTG-IgA and total IgA at diagnosis and periodically or if symptomatic (diarrhoea, iron deficiency, growth failure). Positive serology warrants confirmatory upper GI endoscopy with duodenal biopsy. Gluten-free diet is the treatment.
8. Hearing
Sensorineural hearing loss (SNHL) is progressive and primarily affects high frequencies (2000–8000 Hz). Conductive loss from chronic otitis media is common in childhood. Management includes:
- Audiology assessment every 3–5 years from age 4 years (annually if abnormal)
- Prompt treatment of otitis media; consider grommets if recurrent
- Hearing aids for SNHL
- Avoid ototoxic medications where possible (aminoglycosides)
9. Metabolic & Hepatic Surveillance
- Annual fasting glucose and/or HbA1c from age 10 years — type 2 diabetes risk is increased
- Annual LFTs — hepatic steatosis and elevated GGT/ALP are common
- Lipid profile every 2–5 years from age 10
- Promote healthy weight, physical activity, and Mediterranean-style diet
10. Psychosocial & Neurocognitive Support
Women and girls with TS often have normal verbal IQ but may experience specific difficulties with non-verbal processing, executive function, visuospatial skills, and mathematics. Psychosocial challenges include:
- Formal neuropsychological assessment at school entry and during adolescence
- Educational support plans (Individual Education Plans) if learning difficulties identified
- Screening for anxiety and depression at every clinic visit (PHQ-A, GAD-7)
- Peer support groups (e.g., Turner Syndrome Association of Australia)
- Counselling regarding body image, short stature, delayed puberty, and fertility
- Social work referral for complex psychosocial needs
Monitoring
Lifelong surveillance is essential. The following schedule is recommended (adapted from international TS consensus guidelines):
| Investigation | Frequency | Notes |
|---|---|---|
| Height/weight/BMI | Every 3–6 months (paediatric) | Plot on TS-specific growth charts |
| Thyroid function (TSH, fT4) | Annually from age 4 | More frequently if initiating GH or on thyroxine |
| Coeliac serology | At diagnosis, then if symptomatic or q2–3 years | tTG-IgA + total IgA |
| Echocardiography / Cardiac MRI | Every 5 years (low risk); 1–2 years (high risk) | MRI preferred from age 12 |
| Blood pressure | Every clinic visit | Target <130/80 mmHg |
| Audiology | Every 3–5 years (annually if abnormal) | Pure tone audiometry |
| LFTs | Annually | GGT, ALP, ALT commonly elevated |
| Fasting glucose / HbA1c | Annually from age 10 | Increased type 2 diabetes risk |
| Lipid profile | Every 2–5 years from age 10 | Cardiovascular risk stratification |
| DXA scan | At age 18–20, then every 2–5 years | Earlier if oestrogen non-adherence |
| IGF-1 (during GH therapy) | Annually | Target <2 SD above age-adjusted mean |
| Renal ultrasound | At diagnosis; repeat if abnormality found | Screen for structural anomalies |
Special Populations
Pregnancy
All pregnancies in TS are HIGH-RISK
Requires tertiary centre with maternal–foetal medicine and adult congenital cardiology. Pre-pregnancy cardiac MRI with aortic measurement is mandatory. Aortic root >2.5 cm/m² = contraindication to vaginal delivery; consider elective caesarean. Monitor blood pressure closely — aortic dissection risk is highest in 3rd trimester and postpartum. Continue levothyroxine and adjust dose (↑ by ~30% in pregnancy).
Paediatrics
Growth hormone therapy
Initiate from age 4–6 years or when height falls below 5th centile. Dose 0.045–0.050 mg/kg/day SC. Monitor growth velocity, IGF-1, and glucose. Pubertal induction at age 11–12 with low-dose transdermal 17β-oestradiol. Neuropsychological testing at school entry. Annual thyroid and coeliac screening.
Adult / Transition
Transition of care
Structured transition from paediatric to adult endocrinology by age 16–18. Adult care focuses on: lifelong oestrogen/progesterone replacement (until age 50), cardiovascular surveillance, metabolic monitoring, bone health, hearing, fertility counselling, and mental health support. Increased risk of type 2 diabetes, hypertension, and premature cardiovascular disease.
Renal Impairment
Structural renal anomalies present in ~30%
Horseshoe kidney and duplex collecting system are common. Baseline renal ultrasound at diagnosis. Monitor renal function (eGFR) annually if structural anomaly. No specific dose adjustments for standard TS medications in mild–moderate renal impairment, but monitor closely.
Immunocompromised
Autoimmune conditions
TS is associated with increased autoimmune disease including Hashimoto's thyroiditis, coeliac disease, type 1 diabetes, and inflammatory bowel disease. Monitor for clinical features of autoimmune conditions. No specific immunodeficiency, but autoimmune disease may require immunosuppressive therapy which increases infection risk.
Aboriginal and Torres Strait Islander Health Considerations
Aboriginal and Torres Strait Islander Health
📚 References
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