Amenorrhoea

Published on 09/03/2015 by admin

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Chapter 2 Amenorrhoea

Puberty

Definition. Puberty is the physiological developmental stage of becoming capable of reproduction (ovulation in the female and spermatogenesis in the male).

Endocrinology of puberty

In the fetus, the hypothalamic–pituitary axis responsible for pubertal development is able to function normally, but chronic inhibitory tone secondary to high levels of sex hormones from the fetoplacental unit inhibits fetal gonadotrophin release. After birth, increasing central nervous inhibition prevents gonadotrophin secretion. Puberty occurs when the gradual rise in gonadotrophin-releasing hormone (GnRH) secretion stimulates the pituitary to release gonadotrophin. With the lowering in central nervous system inhibition, there is an increase in hypothalamic generation of GnRH and increasing ovarian sensitivity to gonadotrophins.

Secondary sexual characteristics

Major physical changes during puberty

• development of secondary sexual characteristics

• changes in body mass and fat distribution

• rapid skeletal growth, with fusion of epiphyses

Secondary female characteristics

These include the enlargement of the ovaries, uterus, vagina, labia and breasts, and the growth of pubic hair.

• Breast development (thelarche) is classified into Tanner stages 1–5. Development normally starts between 8 and 13 years of age. It is the first physical sign of puberty and is primarily controlled by ovarian oestrogens.

• Pubic hair growth usually begins with the appearance of breast buds. It is under the control of adrenal androgens. There is a high correlation between breast and pubic hair stages.

• Growth in height usually occurs, with the peak growth velocity coinciding with Tanner stages 2–3 (at about 12 years of age). In the year of maximum growth, 6–11 cm is added to the height.

• Axillary hair growth begins at about 12.5–13 years of age. It takes about 15 months from the first appearance of axillary hair to achieve adult distribution.

• Menarche occurs at the average age of 13 years (range 12.2–14.2 years). It occurs within 2 years of the onset of breast development, regardless of the age at which this occurs. Menarche occurs after the peak of the growth spurt in height.

• Skeletal age corresponds better to maturity than chronological age.

• Vaginal length increases before the development of secondary sexual characteristics. There is also enlargement of the vulva.

• Uterine growth is mainly due to enlargement of the myometrium.

Primary amenorrhoea

Definition. Primary amenorrhoea is defined as no spontaneous uterine bleeding by age 16 years when normal growth and secondary sexual characteristics are present, or no sexual development by age 14.

The average age of menarche is 12.7 years. The requirements for having menses are:

• a functional outflow tract and uterus

• normal ovarian hormone production and follicular development

• anterior pituitary stimulation

• hypothalamic/central nervous system regulation

Management of primary amenorrhoea

When to investigate

• no sexual development by age 14 years

• no spontaneous menstruation by age 16 years or within 2 years of onset of breast development

Before evaluation, exclude:

• chronic disease

Examination

• height, weight, blood pressure

• webbed neck, inguinal hernia

• secondary sexual characteristics (feminising, masculinising, infantile)

• genitalia (avoid vaginal examination if the patient is not sexually active; instead, part the labia to observe, for example, an imperforate hymen)

Investigations

Investigations will depend on historical and clinical findings:

• ultrasound scan of the pelvis, magnetic resonance imaging (MRI)

• follicule-stimulating hormone (FSH), luteinising hormone (LH), prolactin, thyroid function tests

• androgens (testosterone, androstenedione, dehydroepiandrosterone sulfate (DHEAS), 17-hydroxyprogesterone)

• endometrial cultures, such as tuberculosis and schistosomiasis where indicated

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