Weighing the accuracy of Tanner staging

Tanner staging is a standard way to assess for the onset of puberty in both boys and girls, but there are some factors that can make an accurate assessment difficult even for seasoned professionals.

Tanner staging uses pubic hair and breast development in girls to gauge the progression through the stages of puberty. A number of studies have suggested that obesity may be linked to earlier onset of puberty,1,2 but adipose tissue on the chest can also develop independent of true breast tissue,3 skewing the Tanner assessment.

Tanner staging is performed separately for pubic hair and breast development. The level of development observed for each, as seen below, is used to assign a stage of reproductive development.

Tanner Staging for Females⁴

Pubic Hair

• Stage 1: No hair
• Stage 2: Light, downy hair
• Stage 3: Thicker, darker (terminal) hair begins to develop
• Stage 4: Terminal hair covers the entire triangle of the pubic region
• Stage 5: Terminal hair covers the entire triangle of the pubic region and extends past the inguinal crease to the thigh

Breast development scale

• Stage 1: No palpable glandular breast tissue
• Stage 2: A breast bud can be felt under the areola
• Stage 3: Breast tissue can be felt outside the areola, but there is no further development of the areola itself
• Stage 4: The areola develops above the contour of the breast
• Stage 5: The areola recedes back into the contour of the rest of the breast and takes on a darker pigmentation, papillae development, and protrusion of the nipple

Assessment of pubic hair growth is usually not a challenge regardless of weight, says Katherine Kutney, MD, a pediatric endocrinologist at Rainbow Babies and Children’s Hospital in Cleveland, Ohio. However, the appearance of pubic hair doesn’t always align with the beginning of central precocious—or premature—puberty. Breast development is the key sign of puberty onset in girls, but girls who are overweight or obese may have excess tissue on the chest that can be mistaken for true breast tissue.

“Breast tanner staging in overweight females is difficult due to lipomastia, but breast development as the key physical exam finding to detect early central puberty is very important,” said Kutney.

Lipomastia can look similar to developed breast tissue when in reality it is simply fat, Kutney stated. However, she added, it’s important to note that lipomastia can also develop along with true breast tissue.

“Distinguishing between these 2 scenarios is difficult,” Kutney explained. “Breast tissue is firm, and estrogen exposure makes the breast bud harder. If a palpable breast bud can be felt—even in the presence of lipomastia—this is suggestive of central puberty.”

If it’s still difficult to make an accurate assessment, Kutney recommended looking for other signs of early puberty like a growth spurt or vaginal discharge. Blood can also be drawn to test hormone levels, but she cautioned that it’s possible for hormone levels to remain low or normal even in cases of early onset of puberty.

Kutney recommended referring any girls who are suspected to be entering central precocious puberty to a pediatric endocrinologist for a more thorough evaluation and potential intervention.

References

1. Lian Q, Mao Y, Luo S, et al. Puberty timing associated with obesity and central obesity in Chinese Han girls. BMC Pediatr. 2019;19(1):1. doi:10.1186/s12887-018-1376-4
2. Brix N, Ernst A, Braskhøj Lauridsen LL, et al. Childhood overweight and obesity and timing of puberty in boys and girls: cohort and sibling-matched analyses. Int J Epidemiol. 2020:834-844. doi: 10.1093/ije/dyaa056
3. Carlson L, Flores Poccia V, Sun BZ, et al. Early breast development in overweight girls: does estrogen made by adipose tissue play a role? Int J Obes. 43:1978–1987. doi:10.1038/s41366-019-0446-5
4. Emmanuel M, Bokor BR. Tanner Stages. StatPearls Publishing. 2021.