What are the first line laboratory tests and imaging studies for a 6-year-old female presenting with premature pubic hair?

First-Line Workup for 6-Year-Old Female with Pubic Hair

For isolated pubic hair in a 6-year-old girl with normal growth velocity and no other signs of virilization, no routine laboratory testing or imaging is required—clinical observation with close follow-up every 3-6 months is appropriate. 1

Initial Clinical Evaluation

Perform Tanner staging to distinguish between isolated premature adrenarche versus true precocious puberty 1:

• Check specifically for breast development (thelarche), as this is the first sign of true puberty in girls, not pubic hair 1
• Assess for other virilization signs: axillary hair, adult body odor, acne, oily skin, clitoromegaly, or genital maturation 1
• Measure height, weight, and calculate growth velocity—plot on growth curves to identify accelerated growth 2

When to Order Labs and Imaging

Observation Only (No Testing Required)

If the child has isolated pubic hair with normal growth velocity, no breast development, and no virilization signs, routine endocrinologic testing is not recommended 1:

• Monitor clinically every 3-6 months for progression 1
• This represents benign premature adrenarche in most cases 1

Testing IS Indicated If:

Order bone age (left hand/wrist X-ray) if: 1, 2

• Accelerated growth velocity is present
• Advanced bone age >2 standard deviations suggests significant androgen exposure requiring further workup 2

Order hormonal labs (LH, FSH, estradiol) if: 1, 3

• Breast development is present (indicates true precocious puberty)
• Elevated basal LH suggests HPG axis activation 1

Order ACTH stimulation test if: 1

• Accelerated growth velocity is documented
• Measures 17-hydroxyprogesterone, DHEA-S, androstenedione, and cortisol to identify enzymatic defects (21-hydroxylase or 3β-hydroxysteroid dehydrogenase deficiency) 1

Order pelvic ultrasound if: 1, 2

• Breast development is present (assess ovarian volume, uterine size, exclude ovarian tumor)
• Virilization signs are present (evaluate for ovarian or adrenal mass)
• Cushingoid features suggest adrenocortical carcinoma 2

Critical Red Flags Requiring Immediate Endocrinology Referral

Refer immediately if: 1

• Breast development (Tanner 2) is present before age 8 years
• Rapid progression of any pubertal signs occurs
• Both breast development and pubic hair are present together (true precocious puberty)

Common Pitfall to Avoid

The most important distinction is recognizing that pubic hair alone does not indicate true puberty activation—it represents adrenarche from adrenal androgen production, not HPG axis activation 1. Overtesting children with isolated premature adrenarche leads to unnecessary anxiety and cost when clinical observation is appropriate 1.