Volumetric Bone Mineral Density in Young Women with Turner’s Syndrome Treated with Estrogens or Estrogens plus Growth Hormone

Abstract

To explore the effects of estrogen replacement therapy (ERT) and recombinant growth hormone (GH) treatment on bone mineral density (BMD) in Turner’s syndrome, we assessed volumetric BMD (vBMD), which is less dependent on body and bone sizes, in these patients at final height. The areal BMD (aBMD) was measured in 26 young women with Turner’s syndrome (age range 17.5–25.0 years) by dual-energy X-ray absorptiometry, and vBMD was calculated. Patients were subdivided as group 1 (n = 12; ERT alone) and group 2 (n = 14; GH + ERT). Years of estrogen exposure were not different between the groups (group 1: 6.4 ± 1.5 years; group 2: 5.3 ± 1.7 years); in group 2, GH therapy was 5.3 ± 1.4 years. Final heights were significantly higher in group 2 than in group 1 (148.1 ± 3.0 vs. 142.0 ± 2.8 cm; p < 0.0001) as well as aBMD (1.073 ± 0.118 vs. 0.968 ± 0.122 g/cm²; p < 0.04). vBMD was higher in group 2 but not significantly different from group 1 (0.374 ± 0.030 vs. 0.358 ± 0.027 g/cm³; p = 0.169). aBMD was reduced with respect to the normative values in both groups (group 1: –1.97 ± 1.04 SDS, p < 0.0001 vs. 0; group 2: –0.93 ± 1.01 SDS, p < 0.005 vs. 0), whereas vBMD was not (group 1: –0.07 ± 0.79 SDS; group 2: 0.42 ± 0.82 SDS). Our data suggest that: in Turner’s syndrome GH administration improves final height and aBMD, but it does not significantly increase vBMD; aBMD reduction in Turner’s syndrome is likely due to the impaired growth and reduced bone size; Turner’s patients on ERT from adolescence show vBMD values in the normal range in young adulthood.

Epidemiological, endocrine and metabolic features in Turner syndrome

“…Therefore, it is not possible to study BMD with the use of DEXA scans without acknowledging the influence of size. A recent study of adolescents calculated volumetric BMD of the spine and found values that were comparable to those of a reference population (145). In an adult population of 60 TS patients, we found slight, but significant reductions in volumetric BMD (vBMD) in the spine, while vBMD at the hip was actually greater in TS compared with an age-matched control group (76).…”

“…Treatment with estrogens is needed to induce maximal peak bone mass in adolescents and young adults (145,253,258,259). This is supported by four longitudinal studies of estrogen deficient as well as estrogen replete adolescents with TS.…”

“…In a small longitudinal study (n ¼ 8), females with Turner syndrome, who previously had received GH treatment and subsequently estrogen, and initially had normal BMD levels, did obtain a decreased lumbar BMD (but normal femoral neck BMD) as young adolescents (144). Since areal BMD measurements are problematic (see below) in Turner syndrome, one study looked at volumetric lumbar BMD in a group of young adults (17 -25 years; n ¼ 26) and found no additive effect of GH treatment (to estrogen treatment) for 5 years in comparison with a matched control group of Turner syndrome females receiving only estrogens (145). High dose GH during long-term treatment (7 years) possibly increased phalangeal volumetric BMD (146).…”

Long-term hormone replacement therapy preserves bone mineral density in Turner syndrome

“…This finding may largely be due to the two-dimensional nature of dual energy x-ray absorptiometry (DEXA) scans (9), which fails to account for the reduced height in TS leading to lower BMD a priori. Studies of volumetric BMD, taking actual body height into account, have shown largely similar volumetric BMD in TS and controls (4,10). Regardless of BMD, end-point studies have documented increased fracture frequency in girls and women with TS (11)(12)(13).…”

Usefulness of phalangeal quantitative ultrasound in identifying reduced bone mineral status and increased fracture risk in adolescents with Turner syndrome

“…[9][10][11][12] Conversely, it was observed that TS patients receiving appropriate oestrogen treatment usually showed normal trabecular BMD after adjusting for body size. [13][14][15][16][17] In addition to Hormonal Replacement Therapy (HRT), Growth Hormone (GH) administration is considered standard treatment for TS girls, but the role of GH in promoting bone accrual has not yet been completely defined. [18][19][20] Several studies reported in TS patients an increase in fracture prevalence and risk that was higher during childhood and after the age of 45.…”