Which hormones should be assessed in a 16-year-old female for endocrine evaluation?

Hormonal Evaluation in a 16-Year-Old Girl

For initial endocrine evaluation of a 16-year-old girl, check: TSH, free T4, prolactin, LH, FSH, estradiol (E2), and AMH as the core panel 1.

Core Hormone Panel

The following hormones form the essential baseline assessment:

• TSH and free T4: Detects thyroid dysfunction (both hyper- and hypothyroidism), which commonly causes menstrual irregularities in adolescents 1
• Prolactin: Identifies hyperprolactinemia, a frequent cause of amenorrhea. Note that prolactin can be elevated by food, sleep, exercise, stress, and breast examination, so timing matters 1
• LH and FSH: The pattern is more critical than absolute values. These distinguish between ovarian insufficiency (high FSH/LH with low E2), functional hypothalamic amenorrhea (low-normal LH with normal FSH), and PCOS (elevated LH/FSH ratio) 1
• Estradiol (E2): Values <20 pg/mL suggest significant hypogonadism; values <50 pg/mL are consistent with functional hypothalamic amenorrhea 1
• AMH (Anti-Müllerian Hormone): Provides information about ovarian reserve 1

Additional Hormones Based on Clinical Presentation

Add these if hyperandrogenism is present (hirsutism, acne, alopecia):

• Total testosterone: More accurate than free testosterone in most laboratories 1, 2
• DHEA-S: Rules out adrenal causes of androgen excess 1, 2
• 8 AM 17-hydroxyprogesterone: Only if late-onset congenital adrenal hyperplasia is suspected 1, 2

Critical Interpretation Points

The pattern of hormone levels matters more than individual values. For example:

• Low-normal LH with normal FSH (FSH > LH) plus E2 <50 pg/mL suggests functional hypothalamic amenorrhea
• Elevated FSH and LH with low E2 (<20 pg/mL) indicates ovarian insufficiency
• Very low or undetectable LH and FSH suggest organic hypothalamic-pituitary pathology requiring brain MRI 1

Common Pitfalls to Avoid

1. Single E2 measurement limitations: E2 reflects only one time point and fluctuates. Persistently low values (<20 pg/mL) are more meaningful than a single measurement 1

2. Assay reliability: Ensure your laboratory uses validated assays, particularly for E2 and testosterone. Many commercial assays lack accuracy at low concentrations 1

3. Normal LH/FSH doesn't exclude pathology: In functional hypothalamic amenorrhea, gonadotropins are often normal despite low estrogen—this confuses many clinicians 1

4. Prolactin false elevations: Multiple factors transiently elevate prolactin. Only values >100 ng/mL warrant extensive evaluation for prolactinoma 1

Mandatory Screening Tests Beyond Hormones

Before attributing symptoms to endocrine causes, exclude:

• Pregnancy (β-hCG)
• Complete blood count, electrolytes, glucose, liver panel: Identifies systemic illness, eating disorders, or metabolic derangements 1
• Hemoglobin A1C: If glucose is elevated 1