Menstrual Disorders: Amenorrhea

Menstrual Disorders: Amenorrhea
Coming up next: Menstrual Disorders: Dysmenorrhea

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  • 0:01 Menstrual Cycle
  • 1:48 Primary Amenorrhea
  • 3:06 Causes of Primary Amenorrhea
  • 6:13 Secondary Amenorrhea
  • 8:14 Treatment
  • 9:21 Lesson Summary
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Lesson Transcript
Instructor: Heather Adewale

Heather has taught reproductive biology and has researched neuro, repro and endocrinology. She has a PhD in Zoology/Biology.

Ever wonder why a woman's normal monthly cycle stops? You know what cycle I'm talking about, the one that comes with PMS! There are many reasons a woman can fail to begin or can lose her monthly cycle. Learn about the more common reasons in this lesson.

Menstrual Cycle

Okay ladies and gents, we all know the deal… Every month women go through that wonderful time period known as PMS! Okay, well PMS actually refers to the symptoms of a woman's monthly menstrual cycle, which normally occurs once every 28 days or so.

But what happens when that cycle is disrupted? And how does a woman lose her menstrual cycle? Well, before we get into that, let's quickly review what happens under normal circumstances, when everything is working correctly.

See, normally the brain, the ovaries and the uterus all communicate with each other using hormones to make sure that:

  1. The ovaries mature and release new eggs
  2. The uterus is ready to house and develop those eggs if they are fertilized
  3. If no fertilization occurs, then the uterus sheds its tissue and prepares for the next month

But sometimes this communication process goes wrong and one or more of our hormones doesn't send out the right signals. When this happens we can get interference with both egg production and preparation of the uterus. Like when you are texting and autocorrect puts in a word you didn't mean to type, or when you send a message but it doesn't go through the network because it's down! Then your message gets messed up and the person on the other end doesn't get the correct message or information. This can happen in your body too but instead of text messages, it's the level of hormones being secreted that are messed up.

Primary Amenorrhea

When this happens a woman's menstrual cycle can stop, a condition known as amenorrhea or the failure to menstruate. I know that's a big word, so let's break it down. The prefix 'a-' means 'without' and 'menorrhea' starts with the same few letters as 'menstrual', right? So we get 'without' and 'menstrual'. Now girls, you may be thinking 'Amen for Amenorrhea' because you don't have to deal with PMS anymore, but this also means that something could be wrong with the reproductive system.

There are two types of amenorrhea: primary and secondary. Let's start with primary amenorrhea. This is when a female fails to begin her monthly menstrual cycle by the age of 16. Now, in biology when you hear a syndrome described as primary, it usually refers to the cause of the condition. Most primary syndromes are caused by a physical problem with a tissue or an organ. So, primary amenorrhea can be caused by an anatomical problem with the female's reproductive system or her HPG axis.

Causes of Primary Amenorrhea

First up gonadal dysgenesis, or more simply put, abnormal development of the gonads, in this case the ovaries, because we are talking about females. Abnormal ovarian development can lead to the failure to produce the hormones estrogen and progesterone. And, just like we broke down the word 'amenorrhea', we can also break down the word 'dysgenesis'. Now, what other words does the prefix 'dys-' appear in? How about 'dysfunctional', which means what? 'Not working properly', right? And what about the term 'genesis'? Well there is generate and generation and well, Genesis, or the first book of the Bible. Any idea what they all have in common? They all refer in some way to a beginning or a creation and development of something. A new idea, a new generation and the beginning of a book. So by this, you can probably infer that dysgenesis refers to abnormal creation or development of something, and in this case we're talking about a woman's ovaries.

Okay, so number one? Abnormal ovaries!! Or, really abnormal development of any part of the female reproductive system could also cause primary amenorrhea. Other causes can include a disorder in the hypothalamic-pituitary-gonadal axis, or the HPG axis, which controls the hormone signaling pathways of reproduction that we talked about earlier and allows the brain to communicate to the ovaries using hormones (or its own version of text messaging).

And sometimes certain reproductive conditions or developmental disorders, such as testicular feminization, can also be a cause. This is a developmental disorder that occurs during fetal development. In females with testicular feminization, it's pretty much exactly as it sounds. They actually have testes, not ovaries. I know, sounds pretty unusual, doesn't it? But believe it or not, it can happen! You see these women are born with a Y chromosome and develop testes as a fetus. However, their body cannot recognize the testosterone being produced by the testes and so the rest of their body develops just like any normal female's would. This is because testosterone is essential in masculinizing the male body, and the female body develops in the absence of testosterone. But there is one key difference! These females don't have any ovaries or uterus - their internal reproductive tract is missing!

So you can see, without ovaries and without a uterus, they wouldn't have the ability to menstruate.

These are just some of the main causes of primary amenorrhea, but what about secondary?

Secondary Amenorrhea

Well, secondary amenorrhea is also the cessation, or stopping, of menstruation, but in this case it refers to the cessation of menstruation for at least 6 months in a woman who has already had established and normal menstrual cycles.

Now, unless the female is pregnant, in which case the amenorrhea is normal, or she is on birth control making a choice to stop her cycle, the causes are usually related to the function of the HPG axis, the ovaries and the uterus. And, since we know all these structures work together that means that if one or more of them isn't working properly, it can disrupt the menstrual cycle.

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