Laboratory Tests for Female Hormone Evaluation
For a comprehensive female hormone assessment, order the following core panel: LH, FSH, prolactin, testosterone, progesterone (mid-luteal phase), and TSH, with timing and interpretation dependent on menstrual cycle status and clinical presentation. 1
Core Hormonal Panel
Gonadotropins (LH and FSH)
- Measure serum LH and FSH on days 3-6 of the menstrual cycle using an average of three samples taken 20 minutes apart for accuracy 1
- Abnormal findings include:
Prolactin
- Obtain morning resting serum prolactin levels (never post-stress or postictal) 1
- Prolactin >20 μg/L is abnormal and requires investigation for hypothyroidism, pituitary tumors, or medication effects 1, 2
- If elevated, confirm with repeat testing as single elevations can be spurious due to stress or prolactin pulsatility 2
- Prolactin >188 μg/L (4,000 mU/L) typically indicates prolactinoma and mandates pituitary MRI 2
Progesterone
- Measure serum progesterone during mid-luteal phase (approximately day 21 of a 28-day cycle) 1
- Progesterone <6 nmol/L indicates anovulation, commonly caused by PCOS, hypothalamic amenorrhea, or hyperprolactinemia 1, 2
Androgens
- Testosterone: Measure on days 3-6 of cycle 1
- Androstenedione: >10.0 nmol/l warrants evaluation for adrenal or ovarian tumors 1
- DHEAS (dehydroepiandrosterone sulfate): 1
- Age 20-29: >3,800 ng/ml is abnormal
- Age 30-39: >2,700 ng/ml is abnormal
- Elevated levels suggest non-classical congenital adrenal hyperplasia
Thyroid Function
- Measure TSH and free T4 immediately as primary hypothyroidism is a common reversible cause of menstrual irregularity and hyperprolactinemia 2
- Thyroid dysfunction should be ruled out in all patients with menstrual irregularity or infertility 1
Metabolic Assessment (When PCOS Suspected)
Glucose and Insulin
- Obtain fasting morning glucose and insulin levels 1
- Abnormal findings: 1
- Fasting glucose >7.8 mmol/L suggests diabetes
- Glucose/insulin ratio >4 suggests reduced insulin sensitivity
- Both are associated with obesity and PCOS
Additional Testing Based on Clinical Context
For Hypogonadism Assessment
- In premenopausal women with menstrual irregularity: Measure serum estradiol with LH/FSH 1
- Low estradiol with elevated LH/FSH confirms hypogonadism 1
For Male-Pattern Features
- If hirsutism or virilization present: Measure free testosterone or calculate free testosterone index (total testosterone/SHBG ratio) 1
- Free testosterone index <0.3 indicates hypogonadism in the context of low total testosterone 1
Critical Timing Considerations
Common pitfall: Hormone levels vary dramatically throughout the menstrual cycle, making timing essential for accurate interpretation 1
- Days 3-6 of cycle: LH, FSH, testosterone 1
- Mid-luteal phase (day 21): Progesterone 1, 2
- Morning fasting: Prolactin, glucose, insulin 1
- Any time: TSH, DHEAS, androstenedione 1
Interpretation Algorithm
When LH/FSH ratio >2 with testosterone >2.5 nmol/L and anovulation (progesterone <6 nmol/L): Diagnose PCOS and proceed with metabolic screening 1, 3
When prolactin >20 μg/L: Rule out hypothyroidism first with TSH, then consider pituitary imaging if persistently elevated 1, 2
When FSH >35 IU/L: Diagnose primary ovarian insufficiency and assess for hormone replacement needs 1
When all gonadotropins and prolactin are normal but anovulatory: Consider functional hypothalamic amenorrhea and assess nutritional status, stress, and exercise patterns 4, 5
Important Caveats
- Testosterone, androstenedione, or LH (alone or in combination) are elevated in 86% of women with PCOS, making these the definitive hormonal tests 3
- LH/FSH ratio has only 41-44% sensitivity for PCOS and should not be used as the sole diagnostic criterion 3
- Medications (antipsychotics, metoclopramide, opioids) can elevate prolactin, requiring medication review before extensive workup 2
- Normal ranges must be defined for each laboratory's specific assay, as absolute values vary significantly between methods 1, 3