Which would explain why amenorrhea is most common among ballet dancers, gymnasts, and long distance runners.

这也能解释为什麽闭经对芭蕾舞者 体操选手及长跑运动员来说很常见。

In females, primary sex characteristic dysfunction includes amenorrhea or absence of menstruation, or oligomenorrhea or irregular menstrual cycle.

在女中，第一功能障碍包括闭经，即无月经，或月经减少，即月经周期不规则。

When this happens, TRH also stimulates prolactin release - so hyperprolactinemia and amenorrhea occur.

与此同时，TRH也刺激泌乳素泌，所以也会出现高泌乳素血症和闭经。

Ok, now, coming back to amenorrhea.

好，现在说回到闭经。

Interestingly, hypothyroidism - a condition where there's low levels of thyroid hormones - can also cause amenorrhea.

有是，甲状腺功能减退症，一种由于甲状腺激素合成及泌减少导致疾病，也可能会导致闭经。

A rarer cause of primary amenorrhea is androgen insensitivity syndrome.

导致原发闭经一个罕见原因是雄激素不敏感综合。

Finally, endocrine disorders can also cause primary amenorrhea.

最，泌疾病也会导致原发闭经。

With functional hypothalamic amenorrhea due to anorexia, there's significant weight loss and decreased bone density which can cause fractures.

由于厌食导致功能下丘脑闭经患者往往减重过度且骨密度下降，易致骨折。

The most common cause of primary amenorrhea is Turner syndrome, where one X chromosome is either completely or partially absent.

最可能原发闭经原因是Turner综合：有一个X染色体完全或者部缺失。

The most common cause of secondary amenorrhea is pregnancy.

最可能继发闭经原因是怀孕。

Issues with the pituitary gland can also cause secondary amenorrhea.

垂体问题也会导致继发闭经。

Another condition that affects the hypothalamic-pituitary-ovarian axis and can be responsible for secondary amenorrhea is polycystic ovary syndrome.

另一种能影响下丘脑-垂体-卵巢轴并可能导致继发闭经疾病是多囊卵巢综合症。

Primary amenorrhea is when a female hasn't had her first menstruation, called menarche, by age 16, despite normal growth and having started puberty.

原发闭经指女在16周岁前没有初次月经（即初潮），尽管生长发育、进入青春期均无异常。

There are many causes of secondary amenorrhea, and when they occur before menarche, all of these can also cause primary amenorrhea.

有许多原因会导致继发闭经，而当它们在初潮前发生时，都会导致原发闭经。

The one symptom of both primary and secondary amenorrhea is, well, the absence of menstruation.

原发和继发闭经共有一个症状是没有月经。

Next, there's functional hypothalamic amenorrhea, which is when there is a decrease in GnRH secretion, leading to low levels of LH, FSH, and estrogen.

其次是功能下丘脑闭经，即由于GnRH泌下降导致LH、FSH和雌激素水平下降。

In practice, nomadic hunter-gatherers space their children about four years apart by means of lactational amenorrhea, sexual abstinence, infanticide, and abortion.

实际上，游牧狩猎采集者通过哺乳闭经、禁欲、杀婴和堕胎等手段将孩子间隔大约四年。

Sometimes though, menstruation either never starts which is called primary amenorrhea or suddenly stops in a person who's previously menstruating which is called secondary amenorrhea.

而有时，（青春期）月经从未出现，这被称为原发闭经；或是原先有月经周期，但突然停止，这就被称为继发闭经。

The first step when evaluating primary or secondary amenorrhea is to rule out pregnancy with a pregnancy test.

评估原发或继发闭经第一步是用孕检排除怀孕可能。

All right, as a quick recap… amenorrhea is the abnormal absence of menstruation in females of reproductive age.

好！快速回顾一下：闭经指育龄期女无月经或月经异常停止。