Even in the presence of typical Turner stigmata, a karyotype is indicated to eliminate the possibility of the presence of any portion of a Y chromosome. Analysis of pooled data suggests that the presence of Y chromosome material is associated with a 12% risk of a gonadoblastoma (38). If a Y chromosome is identified, laparoscopic prophylactic gonadectomy is recommended at the time of diagnosis to eliminate the risk of malignancy. Although gonadoblastomas are benign tumors with no metastatic potential that can arise spontaneously in gonads containing a portion of a Y chromosome, they can be precursors to germ cell malignancies, such as dysgerminomas (most commonly), teratomas, embryonal carcinomas, or endodermal sinus tumors (39). In individuals in whom there is no evidence of neoplastic dissemination, the uterus may be left in situ for donor in vitro fertilization and embryo transfer.
Individuals with Turner syndrome are at increased risk of sudden death from aortic rupture or dissection resulting from cystic medial necrosis during pregnancy, and the risk may be as great as 2% or more (40). In addition, this may occur even if the aortic root diameter is normal. Because of their small stature, ascending aortic diameters of less than 5 cm may represent significant dilatation. Thus, the use of the aortic size index (ascending aortic diameters measured by MRI at the level of the right pulmonary artery normalized to body surface area) is preferred (41). Patients with an aortic size index greater than 2.0 cm/m2 require close cardiovascular surveillance and those with an aortic size index of 2.5 cm/m2 or more are at highest risk for aortic dissection. In fact, the risk of acute aortic dissection is increased by more than 100-fold in young and middle-aged women with Turner syndrome. If pregnancy is being considered, preconception assessment must include cardiologic evaluation with MRI of the aorta.
The evaluation of other commonly involved organ systems should include a careful physical examination, with special attention to the cardiovascular system, and thyroid function tests (including antibody assessment), fasting blood glucose, renal function tests, and intravenous pyelography or a renal ultrasonography.
Treatment of Turner Syndrome To increase final adult height, commonly accepted treatment strategies include use of exogenous GH (42–44). With recombinant human GH use, the average height gain varied from 4 to 16 cm. It appears that early initiation of therapy (between 2–8 years of age), gradually increasing the dose, and continuing treatment for a mean of 7 years can lead to achievement of a final height greater than 150 cm in most patients (43). Weekly doses of GH of 0.375 mg/kg divided into seven daily doses are typical. Therapy may be continued until a satisfactory height is attained or until little growth potential remains (bone age ≥14 years and growth velocity <2 cm per year). It is not clear if a nonaromatizable anabolic steroid such as oxandrolone will provide additional growth. In girls older than 8 years of age or those with extreme short stature, consideration can be given to using higher doses of GH and adding oxandrolone (45). The dose of oxandrolone should be 0.05 mg/kg per day or less, as higher doses will result in virilization and more rapid skeletal maturation. In addition, liver enzymes should be monitored.
The gonadal steroid treatment of patients with Turner syndrome is as follows: 1.
To promote sexual maturation, therapy with exogenous estrogen should be initiated when the patient is psychologically ready, at about 12 to 13 years of age, and after GH therapy was administered for several years. Low-dose estrogen can be introduced at this time without compromising final adult height (46).
2.