Turner Syndrome Workup

Updated: Jul 12, 2017
  • Author: Maala S Daniel, MBBS; Chief Editor: Luis O Rohena, MD, FAAP, FACMG  more...
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Workup

Laboratory Studies

Diagnosis

A standard 30-cell karyotype analysis is required for diagnosis of Turner syndrome, in order to exclude mosaicism. [10] Diagnosis is confirmed by the presence of a 45,X cell line or a cell line with deletion of the short arm of the X chromosome (Xp deletion).

The buccal smear for Barr bodies is obsolete.

A male phenotype excludes the diagnosis, regardless of karyotype. [11]

Y chromosome

Patients with Turner syndrome should be investigated for the presence of Y chromosomal material using a Y-centromeric probe. These patients may have malignant gonadoblastomas or testicular tissue. [29] The presence of virilization requires a thorough search for gonadal, adrenal, or midline tumors.

Patients with 45,X/46,XY mosaicism may have mixed gonadal dysgenesis and are at a high risk for gonadoblastoma. These patients may require a prophylactic gonadectomy to prevent death from malignancy.

Patients with ring chromosomes or fragments of chromosomes should be examined for Y chromosomal material for the same reason.

Gonadotropins

Both LH and FSH may be elevated in untreated patients younger than 4 years. Gonadotropins are later suppressed to normal or near-normal levels, only to rise to menopausal levels after age 10 years. [12]

Assess both LH and FSH levels prior to initiating estrogen replacement therapy.

Thyroid function tests

Because of the high prevalence of hypothyroidism in Turner syndrome, [6] obtain thyroid function tests at diagnosis.

Thyroid-stimulating hormone (TSH) measurements should be repeated every 1-2 years or if symptoms develop because patients may develop hypothyroidism at a later age.

Glucose metabolism

Abnormalities of glucose metabolism, including overt diabetes mellitus, are more common than in unaffected children.

Urinalysis for glucose should be performed at each follow-up visit with patients taking oxandrolone or human growth hormone.

Continuing care

As routine health maintenance, patients with Turner syndrome should have blood urea nitrogen (BUN), creatinine, fasting blood sugar (FBS) or hemoglobin A1C, fasting lipids, liver enzymes, free thyroxine (T4), and TSH levels measured annually after childhood.

Virilization

Signs of excess androgens are generally absent. If virilization occurs, a search for Y chromosomal material by fluorescent in situ hybridization (FISH) or polymerase chain reaction (PCR) is necessary as part of an evaluation for possible gonadoblastoma. [29]

Diabetes mellitus testing

A prospective study of 113 Italian patients with Turner syndrome showed that diabetes mellitus is a common finding, suggesting it is specific to the syndrome. The study also demonstrated that oral glucose tolerance test is a more sensitive test than HbA1c for the diagnosis of diabetes mellitus in Turner syndrome. [30]

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Imaging Studies

Renal

At diagnosis, perform ultrasonography of the kidneys and renal collecting system.

Annual urine cultures and measurement of BUN and creatinine levels are recommended for those patients with abnormalities of the renal collecting system that predispose to obstruction.

Cardiovascular

Upon diagnosis, evaluate the heart and aorta with echocardiography, magnetic resonance imaging (MRI), or both.

Measure 4-limb blood pressures, because of the high incidence of coarctation of the aorta.

A cardiologist should monitor abnormalities.

Because of the risk of aortic dissection, cardiovascular examinations should be repeated every 5 years during adulthood.

A complete cardiovascular evaluation should be completed prior to attempting assisted reproduction. [31]

Bone age

Bone age is usually normal prior to adolescence but is delayed afterward because of the lack of estrogens

Obtain bone age before starting growth hormone or estrogen therapy. Growth hormone does not increase height if the epiphyses are fused, and growth hormone is contraindicated if epiphyses are fused.

Bone density

Osteoporosis is common but may be overdiagnosed in short individuals. [32]

Measure bone density initially in adults and 3 years later.

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Other Tests

Audiology is indicated in patients with Turner syndrome.

Infants diagnosed at birth should have a hearing assessment in the nursery. Otherwise, formal hearing assessment is recommended at age 1 year and before entering school. Formal re-evaluation every 5 years has been recommended.

More frequent testing is needed in children with repeated otitis media.

Adults should also have a hearing evaluation at least once with further testing later if hearing loss is suspected.

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