••• Chapter 53^ Amenorrhea^529
❍ When should you order a karyotype in patients with 2∞ amenorrhea?
In all patients age <30 or shorter than 60 inches with ovarian failure.
❍ What is the most common chromosomal abnormality causing gonadal failure and primary amenorrhea?
45, X (Turner syndrome—50%).
❍ True or False: In Turner syndrome, the specific phenotype relates to the parental origin of the
X chromosome and most patients retain the maternal X.
True.
❍ Partial deletions of the X chromosome can also cause amenorrhea. What is the characteristic of patients who
have the deletion in part of the long arm of the X-chromosome (Xq-)?
Sexual infantilism, normal stature, no somatic abnormalities, and streak gonads.
❍ What is the characteristic of patients with Xp- (deletion of the short arm of the X-chromosome)?
Phenotypically similar to Turner syndrome.
❍ Primary amenorrhea is associated with various mosaic states 25% of the time, the most common of which is?
45X/46XX (mixed gonadal dysgenesis).
❍ How does “pure gonadal dysgenesis” differ from “gonadal dysgenesis”?
Gonadal dysgenesis is absent ovarian function associated with abnormalities in the sex chromosomes. In pure
gonadal dysgenesis, individuals have primary amenorrhea, with normal stature and no chromosomal abnormalities.
Hence, the gonads are usually streaks.
❍ What is Perrault syndrome?
46XX gonadal dysgenesis + neurosensory deafness.
❍ What enzyme deficiency may be associated with either 46,XX or 46,XY and cause primary amenorrhea?
17 a-hydroxylase deficiency. Patients with this deficiency have primordial follicles, but gonadotropin levels are
elevated because the enzyme deficiency prevents synthesis of sex steroids.
❍ What distinguishes a patient with 46XX 17a-hydroxylase deficiency from one with the same deficiency but
an XY karyotype?
Patients with 46,XY karyotypes lack a uterus. Both of these patients have primary amenorrhea, no secondary sexual
characteristics, female phenotypes, hypertension, and hypokalemia.
❍ Name two other enzyme deficiencies that result in a female phenotype with an XY karyotype.
5 a-reductase deficiency and 17–20 desmolase deficiency.
❍ What is the diagnosis of a patient with normal FSH and LH but with a negative progestational challenge
test (assuming normal outflow tract)?
Pituitary-CNS failure (patient needs sella turcica imaging).