General Topics

Overview of Female Reproductive Endocrinology | Endocrinology

What is female reproductive endocrinology?

The hormonal interaction between the hypothalamus, the anterior pituitary gland, and the ovaries regulate the female reproductive endocrinology system. The hypothalamus secretes a small peptide, gonadotropin-releasing hormone (GnRH), also recognized as a luteinizing hormone-releasing hormone.

GnRH regulates the release of gonadotropins, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) from specialized (gonadotropic) cells in the anterior pituitary gland (see figure The CNS-hypothalamic-pituitary-gonadal target organ axis). These hormones are released in short bursts (pulses) every 1 to 4 hours. LH and FSH promote ovulation and stimulate the secretion of the sex hormones estradiol (an estrogen) and progesterone from the ovaries.

Estrogen and progesterone circulating in the bloodstream almost completely bound to plasma proteins. Only free estrogen and progesterone appear to be biologically active. They stimulate the target organs of the reproductive system (eg, breasts, uterus, vagina). They are usually inhibitory, but in certain situations (eg, around ovulation), they can stimulate gonadotropin secretion.


Puberty is the order of events in which a child acquires adult physical characteristics and reproductive volume. Circulating levels of LH and FSH are elevated at birth, but drop to low levels within a few months and remain low until puberty. Until puberty, few qualitative variations occur in reproductive target organs.

Age of onset of puberty: The age of onset of puberty and the rate of development through diverse stages are influenced by different factors. Over the past 150 years, the age at which puberty begins has been decreasing, primarily due to better health and nutrition, but this trend has stabilized. Puberty often occurs earlier than average in moderately obese girls and later than average in underweight and malnourished girls.

Such explanations suggest that critical body weight or amount of fat is essential for puberty. Many other factors can influence the onset of puberty and how quickly it progresses. For example, there is some evidence that intrauterine growth restriction, especially when followed by postnatal overfeeding, can contribute to earlier and faster development of puberty.

Puberty occurs earlier in girls whose mothers matured earlier and, for unknown reasons, in girls who live in urban areas or who are blind. The age of onset of puberty also varies between ethnic groups (eg, it tends to be earlier in blacks and Hispanics than in Asian and non-Hispanic whites).

Physical changes of puberty: The physical changes of puberty occur consecutively during adolescence (see figure Puberty, when female sexual characteristics progress). Mammary budding (see figure Schematic representation of Tanner stages I to V of human mammary maturation) and the onset of the growth spurt are generally the first recognized changes.

Subsequently, pubic and axillary hair appear (see figure Schematic representation of Tanner’s stages I to V for pubic hair development in girls), and accelerated growth peaks.

Menarche (the first menstrual period) occurs about 2 to 3 years after the breast buds. Menstrual cycles are typically irregular at menarche and can take up to 5 years to become regular. The growth spurt is limited after menarche. Body habit changes and the pelvis and hips widen. Body fat increases and accumulates on the hips and thighs.

Mechanisms that initiate puberty: The mechanisms that initiate puberty are unclear.

Central influences that regulate GnRH release include neurotransmitters and peptides (eg, gamma-aminobutyric acid [GABA], kisspeptin). These factors can inhibit GnRH release during childhood and then initiate its release to induce puberty in early adolescence. In early puberty, hypothalamic GnRH release becomes less sensitive to inhibition by estrogen and progesterone.

The resulting increase in GnRH release promotes the secretion of LH and FSH, which stimulates the production of sex hormones, primarily estrogen. Estrogen stimulates the development of secondary sexual characteristics.

The growth of pubic and axillary hair can be enthused by the adrenal androgens dehydroepiandrosterone (DHEA) and DHEA sulfate; the manufacture of these androgens increases several years before puberty in a process called adrenarche.

The Hypothalamic Pituitary Gonadal (HPG) Axis of Amphibians

Reproductive endocrinology has been characterized mainly in anurans (frogs, toads) with some corroborative data from urodeles (salamanders, newts). Gymnophionid amphibians (caecilians or apodans) are similar to urodeles, although endocrine details are not well understood.

The hypothalamus controls gonadotropin secretion through the release of GnRH (see Tsai (2011)). Amphibian FSH stimulates spermatogenesis in males, as well as follicle development and estrogen secretion in females.

What regulates the female reproductive endocrinology cycle?

The menstrual cycle is regulated by hormones. Luteinizing hormone and follicle-stimulating hormone, which are bent by the pituitary gland, promote ovulation and kindle the ovaries to produce estrogen and progesterone.

What are the two female reproductive endocrinology cycles?

A fertile woman exhibits two periodic cycles: the ovarian cycle, which occurs in the cortex of the ovary, and the menstrual cycle, which occurs in the endometrium of the uterus. The phases of the menstrual cycle are under the control of the hormones unseen during the different phases of the ovarian cycle.

What are the 2 main female reproductive endocrinology hormones?

The two main feminine sex hormones are estrogen and progesterone. Although testosterone is considered a male hormone, women also produce and need a small amount of it as well.

What are the 5 main functions of the endocrine system?

  • Endocrine system function
  • Growth and development
  • sexual function and reproduction
  • heart rate
  • blood pressure
  • sleep and wake cycles
  • body temperature

How does the endocrine system touch the female reproductive endocrinology system?

The endocrine glands release hormones into the bloodstream. This allows hormones to travel to cells in other parts of the body. Endocrine hormones help control mood, growth, and development, the way our organs function, metabolism, and reproduction. The endocrine system regulates the amount of each hormone that is released.


Delayed Puberty | Treatment Options | Endocrinology

What has delayed puberty?

Delayed puberty is defined as the absence of expected sexual maturity. Puberty is an interval characterized by the acquisition of the secondary sexual characteristics, accelerated linear growth, increase in the secretion of sex hormones, maturation of gonads (testes in boys; ovaries in girls), and the potential for reproduction. It is typically complete within 2 to 5 years. Delayed puberty is defined as the lack of any pubertal signs by the age of 13 years in girls and 14 years in boys

More often, children develop later than their peers but eventually develop normally. Sometimes delayed puberty can be due to chronic medical problems, hormonal disorders, radiation therapy or chemotherapy, irregular diet or excessive exercise, genetic defects, tumors, and some infections.

Lack of testicular enlargement in boys and lack of menstruation of the breasts and structures in girls are common symptoms. Diagnosis is based on the results of the physical examination, various laboratory tests, bone age X-rays, and, if necessary, genetic testing, and MRI.

Treatment depends on the cause and may include hormone replacement therapy. Sexual maturity (puberty) begins when the hypothalamus gland begins to secrete a chemical called gonadotropin-releasing hormone. The pituitary gland responds to this signal by releasing hormones called gonadotropins, which stimulate the growth of the sex glands (testicles in boys and ovaries in girls).

The growing sex glands secrete testosterone in boys and sex hormones called estrogen in girls. These hormones cause the development of secondary sexual characteristics, including facial hair and muscle mass in boys, breasts and pubic and armpit hair in girls, and sexual desire (libido) in both sexes.

  • Some adolescents do not begin their sexual development at a normal age.
  • In boys, delayed puberty is very common and defined
  • The testes (testes) do not expand by age 14
  • It has been more than 5 years since the start of genital growth
  • In girls, delayed puberty is defined
  • No breast development at age 13
  • More than 3 years have passed from the start of breast growth to the first trimester
  • At age 16, there is no amenorrhea.

Symptoms of delayed puberty

If you are a girl, you may notice:

  • Your breasts will grow
  • Your pubic hair will grow
  • You have growth
  • You have your period (structural menstruation)
  • Your body is curly with wide hips

If you are a person, you may notice:

  • Pubic and facial hair begins to grow
  • You have growth
  • Your testicles and penis will get bigger
  • Your body shape changes: your shoulders expand and your body becomes more muscular
  • These changes are caused by sex hormones (testosterone in boys and estrogen in girls), your body produces much greater amounts than ever.

What causes delayed puberty?

A few different things can delay puberty.

Constitutional growth retardation (CGD)

  • CGD is a temporary delay in skeletal growth that prevents the child from being as tall as her peers for a time.
  • In boys, 60 per cent of the time, the delay is due to the constitutional growth retardation of puberty.
  • It’s hard to say for sure, but CGE is expected to affect boys twice as much as girls.
  • CGD is a common growth variant, but it still causes pain in children.
  • As we grow, our bones “mature.” If a child has CGD, a doctor may look at an X-ray of her hand and wrist and see that her bones appear “smaller” than expected over time.
  • CGD is often inherited. If one or both parents are “late,” your child may be, too.
  • Boys with CGD reach puberty and reach the appropriate adult height, not as quickly as their peers.
  • The underlying medical condition

These may include:

Heart disease

  • Celiac disease (which affects a child’s ability to gain weight, making it difficult for them to grow at par)
  • Conditions that prevent the hypothalamus or pituitary gland from sending the “early puberty” signal
  • Conditions that prevent the ovaries or testicles from responding to the “onset of puberty” signal
  • Certain genetic conditions, such as Klinefelter syndrome in boys and Turner syndrome in girls
  • Some psychiatric medications can help delay puberty.

Diagnosis of delayed puberty

  • Physical exam: An early puberty evaluation should include a complete history and physical examination to assess puberty development, nutritional status, and growth.
  • X-ray of bone age: Doctors usually take one or more X-rays of the bones (called bone age X-rays) to see the level of bone maturity.
  • Blood test: Doctors take blood samples and perform basic laboratory tests to discover signs of chronic disease, hormone level tests, and genetic tests.
  • Sometimes MRI: Magnetic resonance imaging (MRI) can be done to confirm that there is no brain tumor or structural abnormality in the pituitary gland.

Doctors usually evaluate boys who do not have signs of puberty at age 14 and girls who do not have signs of puberty at age 13 or 16 years. If these children look healthy, they will have a constitutional delay. The doctor may decide to re-examine those in their teens over a 6-month period to make sure puberty begins and develops normally. Girls with severe delays should be screened for primary amenorrhea.

Treatment of delayed puberty

  • Treat the cause: Treatment of delayed puberty depends on its cause. When the underlying disorder causes puberty to be delayed, puberty generally continues after the disorder has been treated. If doctors find a problem, they can send a teenager to see a pediatric endocrinologist, a doctor who specializes in treating children and adolescents who have a treatment problem, or another specialist for further testing or treatment.
  • Hormonal therapy: We can treat delayed puberty with hormone therapy. Even if your child has a constitutional developmental delay (CGD) and progresses at his or her own pace through adolescence, having a “boost” to adolescence through hormone therapy can go a long way to his overall well-being. You, your pediatrician, and your child will discuss whether it is the right option for her.

Some late blooming people wait until the onset of puberty changes. So doctors can offer hormone therapy:

  • Adolescence that is naturally delayed in development does not require treatment, but if adolescence is very stressed due to a delay or absence, some doctors may prescribe supplemental sex hormones to speed up the process. This treatment is very common in children. Children who are late for puberty need extra support from their parents, family, and friends to maintain a healthy body image and self-esteem.
  • Boys may be given a short course of testosterone (usually a monthly injection for 4 to 6 months) to initiate puberty changes.
  • Girls can be given low doses of estrogen for 4 to 6 months to start breast development.
  • After treatment, teens often take their own hormones to complete the puberty process. If not, your doctor will discuss long-term sex hormone replacement.
  • Genetic defects cannot be cured, but hormone therapy can help develop sexual symptoms.
  • Surgery is needed to remove the pituitary tumors, and these children are at risk for hypopituitarism (a deficiency of one or more pituitary hormones).