In this lecture, we’re going to discuss primary amenorrhea. Let’s review the normal menstrual cycle.
Menstruation is dependent on ovulation, estrogen, and progesterone. The average age of menarche
is around 12.7 years. Two thirds of girls experience menarche in the genital Tanner stage
of Tanner stage IV, not V but IV. The definition of primary amenorrhea is when a girl has not developed
menarche by the age of 14 in the absence of pubertal development or she hasn’t developed menarche
by the age of 16 regardless of whether there’s pubertal development. So, what causes primary amenorrhea?
There can be genetic, endocrine, nutritional, or anatomical defects that result in a primary amenorrhea
when she just isn’t developing her period. The etiology of primary amenorrhea is basically rooted on the fact
that the ovaries are not producing sufficient estrogen to proliferate uterine lining or induce ovulation.
This can be because of two major causes, either patients have a hypogonadotropic hypogonadism
which is an inadequate release of gonadotropins, LH and FSH from the pituitary resulting in
a lack of ovarian response or the patients have hypergonadotropic hypogonadism. In this case,
they have lots of FSH and LH coming down but there’s an inadequate ovarian response to these gonadotropins.
Alternatively, there can be a problem with the anatomic aspects of this patient. So for example,
they may have an absent uterus or a genital outlet obstruction such as an imperforate hymen.
So, when we see a patient with primary amenorrhea, it’s important to ask questions about the entirety
of their history and do a good physical exam. We need to ask about and investigate other signs
of pubertal progression. Does the patient have breast development? What Tanner stage is the child?
We need to ask about the age of menarche in the mother and the sisters as a delay may run in the family.
We need to ask about menstrual, gynecologic, and pubertal problems that run in the family.
We should always ask about sexual activity. Additionally, we should ask if the patient has abdominal
pain or cramping. This is how for example an imperforate hymen would present. It’s important
and critical to ask about diet and exercise habits. One of the most common causes
of primary amenorrhea is an excessive exercise routine or just a very competitive exercise routine
or excessive dieting or just a very thin girl. These are all reasons why girls may have a delay
in the onset of their menses. Also, we need to ask questions that will drill down on underlying
hormonal problems. For example, if the patient is very short, she might have Turner syndrome
which may be part of the problem. So, during our physical exam, it’s important to assess the Tanner stage.
It’s important to measure growth parameters and specifically a low BMI may delay onset of menses.
This is in athletic kids or in kids who are dieting. Additionally, short stature may indicate
a genetic or endocrine disorder which is part of the problem. Next, we need to assess
for an endocrinopathy or a genetic disease. Through the genital exam, we need to check
the hymenal opening, checking for an obstruction by a thin membrane or a bulging menses underneath.
We need to check for an enlarged clitoris which may be a result of excess androgens.
We should look at the Tanner stage of the patient. We should do a general vaginal exam.
So, the differential diagnosis for primary amenorrhea is important. In a patient with absent breast
development, there’s probably inadequate estrogen production. In a patient with an absence
of the uterus, you might suspect an abnormal Müllerian development or a XY karyotype
for a phenotypic female. In a patient with a presence of a uterus and breasts, you might think about
obstruction of menstrual flow or an HPO axis difficulty. So, what lab tests will we get in these patients?
Certainly, a pregnancy test is always indicated. It’s easy to do. It’s cheap. It’s unlikely to be a cause
but you would hate to miss that. Additionally, we’ll generally check hormone levels.
We’ll check androgens, thyroid function, and prolactin. This is a way of getting at both the HPO axis,
the thyroid gland, and the pituitary. In some cases where we suspect there might be a problem
in terms of the development of the Müllerian system, we will definitely get a karyotype.
For example, if the patient has an abnormal uterus or if there is no signs of puberty by the age of 14.
A pelvic ultrasound may be useful to identify and evaluate the anatomy of the patient’s genitourinary system.
If we suspect the problem is a central problem, for example if there’s a low LH and FSH,
we might want to do an MRI of the head or the pituitary especially if there is an elevated prolactin level
as well or if there are abnormal neurologic findings. So, how do we treat primary amenorrhea?
If a patient has either hypergonadotropic or hypogonadotropic hypogonadism, we usually will start
the patient on oral contraceptive pills. This is going to allow us to regulate the cycle and standardize
their hormonal fluctuation. Additionally, if they have imperforate hymen, this requires a surgical correction.
In fact, it’s pretty emergent. We may choose to consult an endocrinologist if we need help
guiding the patient through puberty and development. Diet and exercise regimens may be important
if we suspect hypothalamic dysregulation due to malnutrition or excessive exercise.
So, in patients with eating disorders or who are powerfully interested in athletics,
sometimes changing their dietary and exercise regimen may be sufficient to bring on their menses.
Additionally, ultrasound may be needed to determine if there are undescended testes
if a patient has androgen insensitivity syndrome. Remember, undescended testes in a phenotypic female
still have oncologic potential. So, that’s my review of primary amenorrhea in kids. Thanks for your time.