Early onset of pubarche

Premature pubarche is classically defined as the development of pubic hair before the age of 8 years in females and 9 years in males. Pubarche is one of the physical changes of puberty but should not be equated with it since it may occur independently of complete puberty. 

The average beginning of pubarche varies due to many factors, including climate, nourishment, weight, nurture, and genes. Pubarche usually results from rising levels of androgens (male sex hormones) from the adrenal glands or the testes (premature adrenarche) but may also result from exposure of a child to an anabolic steroid. Generally, premature pubarche has been attributed to an early maturation of the zona reticularis of the adrenal cortex leading to an increase of adrenal androgens to levels normally seen in early puberty and, in turn, to the premature appearance of pubarche. Because half of premature pubarche patients have normal androgen levels, a hypersensitivity of the hair follicle to steroid hormones has also been proposed.

Rarer causes include precocious puberty, congenital adrenal hyperplasia (group of inherited genetic disorders that affect the adrenal glands), and androgen-producing tumors of the adrenals or gonads. 

Once precocious puberty and nonclassic congenital adrenal hyperplasia are ruled out, no treatment is needed. However, a long-term follow-up of these patients is warranted.

Symptoms

The premature pubarche is referred to the appearance of pubic hair before the age of 8 years in females and 9 years in males, without other signs of puberty referred to the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction.

Associated diseases

• obesity
  
• polycystic ovary syndrome (PCOS)
• nonclassic congenital adrenal hyperplasia

Some authors have shown an association between premature pubarche and later development of insulin resistance, dyslipidemia (abnormal amount of lipids in the blood), PCOS, and metabolic syndrome (cluster of conditions - increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol or triglyceride levels - that occur together); however, in most cases, it represents a variant of normal pubertal development.

Complications

Overweight is a common finding in premature pubarche although birth weight is normal. What is important is that these children should be encouraged to lose weight because premature pubarche and obesity are associated with an increased risk of developing PCOS and metabolic syndrome in adulthood.

Risk factors

• premature adrenarche
• smallness for gestational age (SGA)
• obesity
• environmental stress

Prevention

Since it is suggested that obesity is closely associated with premature pubarche, it is recommended to prevent it.

Thelarche (onset of breast development) and pubarche represent observable markers of underlying hormones that are dependent on the maturation of unique endocrine axes, i.e., the hypothalamic-pituitary-gonadal (HPG) and hypothalamic-pituitary-adrenal (HPA) axis, respectively. Premature pubarche has been associated with a relative adrenal hyperandrogenism and hyperinsulinemia (high blood level of insulin). Those girls are at higher risk of developing ovarian hyperandrogenism (excess of male sex hormones – androgens), polycystic ovary syndrome and oligomenorrhea (infrequent menstruation) causing ovulatory dysfunction, which can lead to infertility because no eggs are released to be fertilized.

It is important to examine early pubertal markers (thelarche and pubarche) separately in an effort to better understand potential hormonal responses. Moreover, these systems may play differential roles in the etiology of downstream health outcomes, such as breast cancer and other reproductive cancers.

Recent data, in fact, indicate that girls with premature pubarche may not have a benign outcome. However, a long-term follow-up of these patients is warranted. However because this may represent the first sign of an abnormal and excess release of adrenal hormones, it should be evaluated. 

Furthermore, hyperinsulinemia is a common feature in adolescent patients with premature pubarche and functional ovarian hyperandrogenism, and is directly related to the degree of androgen excess. Future fertility depends on follow-up of those consequences.