Premature thelarche

Premature thelarche (PT) is a medical condition, characterised by isolated breast development in female infants. It occurs in females younger than 8 years, with the highest occurrence before the age of 2. PT is rare, occurring in 2.2-4.7% of females aged 0 to 2 years old. The exact cause of the condition is still unknown, but it has been linked to a variety of genetic, dietary and physiological factors. Premature thelarche (PT) is a medical condition, characterised by isolated breast development in female infants. It occurs in females younger than 8 years, with the highest occurrence before the age of 2. PT is rare, occurring in 2.2-4.7% of females aged 0 to 2 years old. The exact cause of the condition is still unknown, but it has been linked to a variety of genetic, dietary and physiological factors. PT is a form of Incomplete Precocious Puberty (IPP). IPP is the presence of a secondary sex characteristic in an infant, without a change in their sex hormone levels. Central Precocious Puberty (CPP) is a more severe condition than IPP. CPP is the presentation of secondary sex characteristics, with a change in sex hormones due to alteration of the hypothalamic-pituitary-gonadal (HPG) axis.}CPP is an aggressive endocrine disorder with harmful developmental consequences for the patient. At the presentation of PT, diagnostics are used to ensure it isn’t early stage CPP. CPP can be differentiated from PT through biochemical testing, ultrasounds and ongoing observation. There is no treatment for PT but regular observation is important to ensure it doesn’t progress to CPP. CPP diagnosis is important as treatment is necessary. Premature thelarche is breast hypertrophy before puberty. This form of hypertrophy is an increase in breast tissue. PT occurs in pre-pubescent females, under the age of 8, having a peak occurrence in the first two years of life. The breast development is usually bi-lateral: both breasts show development. In some cases development may be unilateral: one breast develops. There are four patterns of PT development. Most patients have hypertrophy followed by complete loss of the excess breast tissue (51% of cases) or loss of most excess tissue, but some remains until puberty (36% of cases). Less commonly patients have ongoing patterns of thelarche: 9.7% suffer from a cyclic pattern where the size of the breast tissue varies over time, and 3.2% experience continual increase in tissue size. The main symptom of PT is enlarged breast tissue in infants. Estrogen’s role in PT, also leads to increased bone age and growth in some cases. In PT these secondary symptoms are minimal: bone age only varies from actual age by a few months and growth velocity only slightly varies from the norm. Diagnostic tests will distinguish these PT secondary symptoms from the more severe bone aging and growth occurring in early CPP. The direct pathophysiology behind PT is still unknown, but there are many postulated causes. PT is linked to increased sensitivity of the breast tissue to estradiol, an estrogen derivative, in certain prepubertal individuals. Sporadic estrogen or estradiol production in the adrenal glands, follicles or ovarian cysts is also linked to the condition. Follicle Stimulating Hormone (FSH) is secreted from the anterior pituitary. FSH plays a key role in development, growth and puberty, thus it is suspected to play a role in PT. Gondotropin-releasing hormone (GnRH) stimulation testing in some patients with PT has shown a dominant response from FSH. This response is linked to active mutations in the FSH receptor and Gs-a subunit in PT. Genetic investigation indicated these mutations only account for few cases of premature PT. PT may also be caused by transient partial activation of the HPG axis. Partial activation would release a surplus of FSH from the anterior pituitary without further disruption of the HPG axis. The consumption or exposure to certain endocrine disrupters have also been linked to PT.