What screening tests are used to diagnose premature maturity in girls?

Screening Tests for Precocious Puberty in Girls

For girls presenting with early pubertal signs, the essential screening tests include baseline gonadotropins (FSH and LH), estradiol levels, bone age radiography, and pelvic ultrasound, with brain MRI indicated for girls under 6 years of age or those with neurological symptoms. 1

Initial Clinical Assessment

Physical examination findings to document:

• Breast development (thelarche) is the primary indicator of puberty onset in girls 2, 3
• Tanner staging of breast and pubic hair development 4
• Growth velocity measurement (>7.0 cm/year suggests central precocious puberty rather than benign variants) 5
• Height, weight, and calculation of predicted adult height 1
• Neurological examination for headaches, visual changes, or seizures 1

Historical elements to obtain:

• Age of symptom onset (precocious if <8 years) 6, 2
• Progression timeline of pubertal changes 1
• Family history of early or late puberty 1
• Potential exposure to exogenous hormones or endocrine disruptors 1

Laboratory Testing

Hormonal evaluation (required for all suspected cases):

• Baseline FSH, LH, and estradiol levels to differentiate central (gonadotropin-dependent) from peripheral (gonadotropin-independent) precocious puberty 1, 6
• For prepubertal girls ≥11 years with failure to initiate puberty, FSH and estradiol measurement is recommended 7
• Thyroid function tests to exclude primary hypothyroidism as a cause 6, 3

Interpretation thresholds:

• Elevated FSH (>35 IU/L) with LH >11 IU/L indicates hypergonadotropic hypogonadism 7
• FSH ≥10 IU/L at age 10 years or older suggests ovarian impairment 7

Radiologic Assessment

Bone age radiography (required for all cases):

• X-ray of left hand and wrist to assess skeletal maturation 1, 6
• Advanced bone age indicates true precocious puberty and helps predict impact on final adult height 1

Pelvic ultrasound:

• Indicated to evaluate ovarian size, rule out ovarian tumors or cysts, and assess uterine development 1, 6

Brain MRI (selective indications):

• Mandatory for girls <6 years of age with central precocious puberty, as they have the highest risk (up to 20-30%) of CNS abnormalities 1, 7
• Strongly recommended for all boys with precocious puberty 6
• Consider for girls 6-8 years based on clinical presentation, though CNS lesion likelihood is lower (2-7%) 1, 7
• Required for any child with neurological symptoms (severe headaches, visual changes, seizures) regardless of age 1
• MRI of sella and hypothalamic-pituitary axis with gadolinium contrast is the preferred imaging modality 1
• Can identify hypothalamic hamartomas, gliomas, arachnoid cysts, and other structural abnormalities 1

Diagnostic Algorithm

Step 1: Document pubertal signs and measure growth velocity

• Growth velocity >7.0 cm/year has 92% sensitivity for central precocious puberty versus benign premature thelarche 5

Step 2: Obtain baseline hormonal levels (FSH, LH, estradiol) and thyroid function

• Elevated gonadotropins indicate central activation of hypothalamic-pituitary-gonadal axis 1

Step 3: Order bone age radiography

• Advanced bone age confirms pathologic early puberty 1

Step 4: Perform pelvic ultrasound

• Evaluates for peripheral causes (ovarian tumors/cysts) 1

Step 5: Brain MRI based on age and clinical features

• Mandatory if <6 years, strongly consider if 6-8 years with rapid progression, required if neurological symptoms present 1, 7

Referral Criteria

Endocrinology consultation is indicated for:

• Prepubertal girls with no signs of puberty by age 13 years with elevated FSH 7
• Girls with confirmed central precocious puberty requiring GnRH analog therapy 1
• Primary amenorrhea by age 16 years despite other pubertal signs 4
• Failure to initiate or progress through puberty normally 4

Common Pitfalls

Avoid these diagnostic errors:

• Assuming all breast development before age 8 is pathologic—benign premature thelarche is common, especially in girls 6-8 years, and can be distinguished by slower growth velocity (<7 cm/year) 5
• Skipping brain MRI in girls 6-8 years—while CNS abnormalities are less common (2-7%), they can be asymptomatic and clinically significant (e.g., craniopharyngioma) 1, 5
• Failing to measure growth velocity—this is the most practical clinical tool to differentiate true precocious puberty from benign variants 5
• Ordering only a single FSH level without estradiol or LH—complete hormonal assessment is needed to classify the type of precocious puberty 1, 6