Turner Syndrome: Treatment and Monitoring Recommendations
Growth Hormone Therapy
Girls with Turner syndrome should begin growth hormone therapy as early as possible when height falls below the 3rd percentile and height velocity is below the 25th percentile, typically starting around age 4-6 years, to optimize final adult height. 1, 2, 3
GH Dosing and Administration
- Administer GH at 0.045-0.05 mg/kg/day via subcutaneous injection in the evening 4
- Continue treatment until epiphyseal closure is documented on wrist radiography or height velocity drops below 2 cm/year 4
- Both reference and biosimilar GH products are appropriate 4
Monitoring During GH Therapy
- Clinic visits every 3-6 months to assess:
Discontinuation Criteria for GH
Stop GH therapy immediately if: 4
- Epiphyseal closure is demonstrated
- Intracranial hypertension develops
- Slipped capital femoral epiphysis occurs
- Height velocity remains <2 cm/year above baseline despite 6 months of treatment
Estrogen Replacement Therapy
Begin low-dose estrogen replacement at age 11-12 years to mimic normal pubertal timing, preserve psychosocial development, and optimize bone and uterine health, even if the patient is still receiving growth hormone. 5, 6, 1, 2, 7
The evidence strongly supports early initiation rather than delaying for growth, as postponing estrogen is detrimental to bone mineral density and uterine development 1, 2, 3. While there was historical concern about compromising height, current data show that low-dose estrogen initiation at the physiologically appropriate age does not significantly impair final height when combined with GH therapy 2, 8.
Pubertal Induction Protocol
Age 11-12 years (Initial dose): 5, 6, 2
- Preferred: Transdermal 17β-estradiol 6.25 μg/day (can use 1/8 of 50 μg patch)
- Alternative if transdermal unavailable: Oral micronized estradiol 0.25 mg/day or 5 μg/kg/day
- Avoid conjugated estrogens and ethinyl estradiol 2
Age 12.5-15 years (Dose escalation): 5, 6
- Gradually increase estradiol dose every 6 months over 2-3 years
- Transdermal progression: 6.25 → 12.5 → 25 → 37.5 → 50 → 75 → 100 μg/day
- Oral progression: 0.25 → 0.5 → 1.0 → 1.5 → 2.0 mg/day
- Target adult dose: 100-200 μg/day transdermal or 2-4 mg/day oral 6, 2
Age 14-16 years (Add progestogen): 5, 6
- Begin cyclic progestogen after 2 years of estrogen therapy or when breakthrough bleeding occurs
- Oral micronized progesterone 100-200 mg/day for 12-14 days per month (preferred for favorable metabolic profile) 6
- Alternative: Dydrogesterone 5-10 mg/day for 12-14 days per month 6
Adult Hormone Replacement
For adults who have completed pubertal induction, use transdermal estradiol 100 μg/day with oral progestogen to minimize cardiovascular and thrombotic risks 2, 9. Combined estrogen-progestogen pills may be used for convenience once adult dosing is achieved 2.
Baseline Evaluations Before Treatment Initiation
Cardiovascular Assessment
- Comprehensive cardiac imaging including cardiac MRI or CT to identify aortic abnormalities, coarctation, bicuspid aortic valve, and dilated ascending aorta 3, 7
- Baseline blood pressure measurement 3
- These findings are critical as Turner syndrome carries increased risk of aortic dissection 3
Endocrine Assessment
- FSH and LH levels (FSH ≥10 U/L at age ≥10 years indicates ovarian insufficiency requiring treatment) 5, 6
- Thyroid function (TSH, free T4) - autoimmune thyroid disease is common 3, 7
- Fasting glucose and HbA1c - increased diabetes risk 3, 7
- IGF-1 and IGFBP-3 if considering GH therapy 3
Bone Health
Renal and Metabolic
- Renal ultrasound to identify structural abnormalities (horseshoe kidney, duplicated collecting system) 3, 7
- Comprehensive metabolic panel including liver function 3
- Lipid profile 3, 7
Reproductive Assessment
- Pelvic ultrasound to assess baseline uterine size and ovarian morphology 8, 7
- Karyotype confirmation if not previously documented 10, 7
Long-Term Monitoring and Surveillance
Annual Assessments
- Cardiovascular: Blood pressure, cardiac MRI every 5-10 years or more frequently if aortic dilation present 3, 7
- Endocrine: Thyroid function (TSH), fasting glucose/HbA1c, lipid profile 3, 7
- Bone health: DEXA scan every 2-5 years depending on baseline results 3, 7
- Liver function: Transaminases (increased risk of fatty liver disease) 3, 7
- Audiology: Hearing assessment (progressive hearing loss common) 3, 7
Reproductive Monitoring
- Pelvic ultrasound to assess uterine growth during pubertal induction 8
- Fertility counseling regarding options including oocyte donation, embryo adoption, and rare possibility of spontaneous pregnancy 7
Critical Considerations and Pitfalls
Androgen deficiency is universal in Turner syndrome and worsens with conventional HRT due to increased SHBG from oral/transdermal estrogen 9. Current guidelines do not routinely address androgen replacement, but clinicians should be aware that testosterone, DHEAS, and androstenedione levels are 30-50% lower than controls 9.
Avoid delaying estrogen replacement beyond age 12 years despite ongoing GH therapy, as this compromises bone mineral density, uterine development, and psychosocial well-being without meaningful benefit to final height 1, 2, 3.
Do not use conjugated equine estrogens or ethinyl estradiol for pubertal induction - these formulations have unfavorable metabolic effects and are not physiologic 2.
Transdermal estradiol is strongly preferred over oral formulations for adult replacement due to lower thrombotic risk, better lipid profile, and avoidance of first-pass hepatic metabolism 2, 3.