Turner Syndrome Aortic Z-Scores

Turner-specific Z scores (Quezada 2015, Table II)

√D[cm] predicted = b0 + b1·BSA + b2·BSA²      BSA = Haycock (0.024265 × Ht^0.3964 × Wt^0.5378)
Z = (√D − predicted) / √MSE

                             b0      b1       b2      MSE
  Aortic valve annulus     0.891   0.414   −0.081   0.007
  Aortic root (sinuses)    1.035   0.589   −0.129   0.009
  Ascending aorta          0.942   0.593   −0.122   0.012
  Sinotubular junction     0.895   0.586   −0.124   0.009
  Proximal transverse arch 0.881   0.539   −0.107   0.012
  Distal transverse arch   0.844   0.428   −0.072   0.012
  Aortic isthmus           0.895   0.279   −0.038   0.014
  Descending aorta         0.676   0.503   −0.094   0.009

• Z formula: the paper prints the regression but not the Z formula, only that the method is analogous to Pettersen 2008. The formula above is our inference: Pettersen’s general form applied to the square-root scale. The Z = 0 and Z = +2 curves this produces match the paper’s Figures 2–9 (our check, e.g. ascending aorta at BSA 1.5: 2.42 and 3.15 cm).
• Population: 481 girls and women with Turner syndrome, 2 to 70 years (the Results say 3 to 70), Turner Syndrome Society of the US meetings 2003–2013. Excluded: aortic stenosis (velocity above 2 m/s), more than trace AR, unoperated structural heart disease, prior dissection or elective aortic surgery. Bicuspid valves (25%) were left out of the equations because only BAV independently enlarged the aorta, so the equations rest on the subjects without BAV. Among all 481, 12% had a history of coarctation repair; the paper does not say whether they were in the fitted equations. Karyotype, age, BMI, blood pressure and growth hormone did not independently change aortic size.
• BSA range: the plotted data run from about 0.5 m²; above about 2.3 m² several curves level off or turn down. The page cautions outside that range (our reading of the plots).
• Thresholds: the paper sets none. Its authors’ own practice (not a guideline): an ascending aorta Z above 3, or a rise of more than 1 when the baseline Z is above 2, is treated; the paper does not say what treatment. The authors predicted that dissection would occur only at Z scores far above +3 (their opinion, not a study finding). Expect Turner Z scores to be lower than general-population Z scores; in their earlier study the number of subjects with general-population root and ascending aorta Z above 2 was 17% and 22% higher than in a healthy general female population.
• Guideline bands (ascending aorta): Gravholt 2024 (current international Turner guideline): under 15 years dilation may be categorised by the Turner-specific Z (R 4.14), bands Z below 2.5, 2.5–3.5, above 3.5 (R 4.16, 4.18–4.20, 4.29–4.31); from 15 years ASI, AHI or Z by Table 12 and R 4.15. GRADE quality is low or very low throughout (R 4.14 is ungraded). Surveillance intervals are only in the guideline’s flow charts (Figures 4–5), so they are not reproduced here. ACC/AHA 2022 section 6.1.2.5 (read in the author manuscript): from 15 years use ASI; ASI above 2.3 imaging at least yearly (1, C-EO); ASI 2.5 or more with risk factors (coarctation, aortic dilation, BAV, hypertension) replacement reasonable (2a, C-LD), without them may be considered (2b, C-EO). 2018 AHA/ACC adult congenital (now superseded by the 2025 ACC/AHA adult congenital guideline, which has no Turner recommendation): replacement in adults reasonable at ASI 2.5 cm/m² or more (IIa, B-NR).
• Verification: checked in October 2026 against ParameterZ’s Quezada module, the calculator cited by the authors’ group (Corbitt 2018) and the AHA 2018 Turner statement (its original server and its successor at rchsd.org/zscore). Z score, expected diameter, Z +2 diameter and BSA agree in every case: 24 simulated patients covering all 8 levels (153 level values), entered in mm and cm. Including guards, notes and the guideline bands, 893 of 893 comparisons agree. Quezada 2015 does not print the Z formula, so this confirms agreement with that calculator, whose code uses the formula above; the coefficients match Table II. The guideline bands have no official calculator and were checked against the Gravholt 2024 text. Gravholt 2024 allows DuBois or Haycock BSA for the ASI (Table 12); this page uses Haycock, which gives a lower ASI than DuBois in heavier women (1.90 vs 2.00 at 150 cm, 70 kg, 33 mm) and can place her one Gravholt band lower: near a cut-off, check the DuBois ASI.

Source

• Quezada E, Lapidus J, Shaughnessy R, Chen Z, Silberbach M. Aortic dimensions in Turner syndrome. Am J Med Genet A 2015;167A:2527–2532. doi:10.1002/ajmg.a.37208 (full text read).
• Gravholt CH, Andersen NH, Christin-Maitre S, et al. Clinical practice guidelines for the care of girls and women with Turner syndrome. Eur J Endocrinol 2024;190(6):G53–G151. doi:10.1093/ejendo/lvae050 (full text read).
• Isselbacher EM, Preventza O, Hamilton Black J 3rd, et al. 2022 ACC/AHA guideline for the diagnosis and management of aortic disease. Circulation 2022;146(24):e334–e482. doi:10.1161/CIR.0000000000001106 (author manuscript read).
• Stout KK, Daniels CJ, Aboulhosn JA, et al. 2018 AHA/ACC guideline for the management of adults with congenital heart disease. Circulation 2019;139(14):e698–e800. doi:10.1161/CIR.0000000000000603 (archived full text read). Superseded by the 2025 ACC/AHA/HRS/ISACHD/SCAI adult congenital guideline (Circulation 2026;153(8):e115–e251).
• Carlson M, Airhart N, Lopez L, Silberbach M. Moderate aortic enlargement and bicuspid aortic valve are associated with aortic dissection in Turner syndrome. Circulation 2012;126:2220–2226 (cited for ASI; as quoted by Quezada 2015).