Changes in the skin at puberty.

What is puberty?

Puberty refers to the period of life during which an individual undergoes physical development and sexual maturation to acquire the ability to reproduce. During puberty, the individual also suffers psychosocial changes and development of secondary sexual characteristics. These are:

• Genital development in males.
• Breast development in females
• Pubic hair in both sexes

What is adolescence?

Adolescence is defined by the transitional stage of physical maturation and psychosocial development, generally occurring from puberty to adulthood. Although the period of adolescence is closely related to adolescence, it is difficult to define a precise time interval for this stage of life. Adolescents experience several types of maturation:

• Biological
• Psychosocial (with early, middle and late stages) [1]
• Cognitive, that is, the development of formal operational thinking [2]

What are the stages of puberty?

Puberty is defined by:

• Adrenarche: the beginning of adrenal production androgens by the adrenal cortex (this occurs before the onset of puberty)
• Pubarche: the appearance of pubic hair
• Thelarche: the appearance of breast tissue
• Menarche: the age of the first menstrual period

Sexual maturity can be classified into stages according to the Tanner staging system: a scale physical development based on primary and secondary sexual characteristics, such as breast and genital size, testicular volume, and pubic and axillary hair (Tables 1-3).

When does puberty occur?

The age at which puberty occurs is highly variable.

In men, according to Tanner's data, the genitals began to enlarge at 95% in children aged 9.5 to 13.5 years (mean 11.6 ± 0.9 years) [3]. Functional puberty, defined by the ability to ejaculate, occurs between the ages of 13-17 years (mean 14.9 ± 1.1 years).

In women, the development of breast buds in the larche is one of the first signs of puberty. This occurs in white North American girls at the age of 9.96 ± 1.82 years, and in African American girls at 8.87 ± 1.93 years. Pubic hair growth begins around age 9 as a result of adrenarche, which is dependent on pituitary ACTH production. The average age at menarche is 13 years, with a range of 10 to 16.5 years.

Which are the physiological skin changes during puberty?

Puberty occurs when gonadotropin-releasing hormone (GnRH) is released from the hypothalamus in the brain. As a result, the pituitary gland (also within the brain) is stimulated to release other hormones (FSH and LH) that act on the sexual organs to produce the hormones estrogen and testosterone.

Testosterone is responsible for several skin changes during puberty. Increase tallow production (oil) and axillary sweating of the apoeccrine sweat glands. It is also the cause of pubic and axillary hair growth.

Hormonal fluctuations in the menstrual cycle also lead to cutaneous changes, including premenstrual exacerbation of pre-existing skin disorders such as psoriasis, atopic eczemaand lupus erythematosus.

Hair changes distribution

After birth, hair is divided into two main types: hair and terminal hair.

• The vellus hair is soft, short (usually <2 cm), no medulado (no tiene un núcleo de células llenas aire) y generalmente nopigmented.
• Terminal hair is longer, often mellow, pigmented and thicker. [3].

Prenatal Lanugo hair, which is characteristically soft, fine, not medullated, and usually pigmented [3], is generally not present after birth.

Before puberty, terminal hair is limited to the scalp, eyelashes, and eyebrows. After puberty, under the influence of androgens, mainly testosterone, terminal hair develops from vellus hair to give rise to secondary hair growth in the armpits and pubic regions. [3].

Changes in the microbiome

The microbiome refers to microorganisms that normally reside on our skin. One study observed greater variation in the microbiome of Tanner stage 1 children compared to Tanner stage 5 individuals. Predominant organisms They are:

• Tanner Stage 1: Streptococcus, Moraxella, Haemophilus and Neisseria
• Tanner Stage 5: Corynebacterium, Cutibacterium and Turicella

Stage 5 bacteria They are lipophilic (oil lover) and are found in sebaceous skin regions such as the scalp, face and upper trunk [4]. The increase in these lipophilic bacteria is probably due to a higher content of epidermal lipids of sebum Colonization of the skin by lipophilic bacteria reduces the skin. pH, which in turn inhibits the growth of pathogens staphylococcus and streptococcus.

Increased density and thickness of hair growth and increased apocrine gland activity at puberty can also affect the microbiome.

What skin conditions can start during puberty?

Rise in androgynous levels at puberty may herald the start of genetically programmed programs family characteristics. These include:

• Male pattern baldness
• Hirsutism
• Hyperhidrosis
• Bad armpit odorbromhidrosis)

Congenital melanocytic naevi (brown birthmarks) may increase in size and become more pigmented during puberty. Prominent terminal hairs may form within them. a becker nevus may appear for the first time. Sebaceous nevi become thicker with an irregular surface.

Skin disorders that tend to begin during adolescence include:

• Acne
• Seborrheic dermatitis
• Pityriasis versicolor
• Hidradenitis suppurativa
• Fox-Fordyce disease
• Polymorphic light eruption
• Psoriasis
• Compulsive skin collection
• Artifact dermatitis

What is precocious puberty?

Puberty is said to be precocious or premature (early) when pubertal signs are observed in boys before the age of 9 and when they are observed in girls before the age of 8. [5]. Children with precocious puberty should be referred to a endocrinologist for investigation Treatment depends on the cause.

Precocious puberty follows early activation of the hypothalamic-pituitary-gonadal axis, when it is known as “true,” “full,” or “central” puberty. Pseudopuberty is defined as sex hormonal secretion independent of normal control mechanisms.

Precocious puberty can be detrimental to behavioral and psychological development, may reduce height in adulthood, and may pose health risks.

What is delayed puberty?

Delayed puberty is defined by the absence of sexual development at the age of 15 in boys and at the age of 14 in girls. [3]. Delayed puberty orders endocrinological investigation. The treatment depends on the cause.

Delayed puberty is usually due to a constitutional delay, that is, puberty is late but otherwise occurs normally. The onset of puberty can be delayed by factors such as malnutrition or excessive exercise, by interfering with hypothalamiccontrol of the onset of puberty.