What baseline metabolic and hormonal tests should I order for a reproductive‑age female with hirsutism, fatigue, anxiety, and diffuse hair loss and no prior PCOS diagnosis?

Baseline Laboratory Testing for Suspected PCOS

Order fasting glucose, fasting insulin, total testosterone (or free testosterone), TSH, prolactin, and lipid panel as your initial metabolic and hormonal workup for this patient with hirsutism, fatigue, and hair loss. 1

Essential First-Line Hormonal Tests

Androgen Assessment

• Total testosterone or free testosterone is the primary test to confirm hyperandrogenism, which is central to PCOS diagnosis 1
• Blood should be drawn between day 3-6 of the menstrual cycle if cycles are present 1
• Total testosterone >2.5 nmol/l is considered elevated and suggests PCOS or other hyperandrogenic conditions 1
• DHEAS measurement should be added if testosterone is normal but clinical suspicion remains high, as it indicates adrenal androgen production 2
  • DHEAS >600 μg/dL requires urgent imaging to exclude adrenocortical carcinoma 2

Ovulatory Function

• Mid-luteal progesterone (drawn during the luteal phase based on cycle timing) confirms anovulation when <6 nmol/l 1
• Low progesterone is common in PCOS, hypothalamic amenorrhea, and hyperprolactinemia 1

Exclude Other Endocrine Disorders

• TSH to rule out thyroid dysfunction, which can mimic PCOS symptoms 1
• Prolactin (morning resting level, not post-ictal) to exclude hyperprolactinemia; >20 μg/l is abnormal 1
  • Rule out hypothyroidism or pituitary tumor if elevated 1

Essential Metabolic Tests

Glucose and Insulin Assessment

• Fasting glucose followed by 2-hour glucose after 75-gram oral glucose load is recommended by ACOG for all women with suspected PCOS due to increased diabetes risk 1
• Fasting insulin helps assess insulin resistance, particularly when the glucose/insulin ratio is >4 1
• Fasting glucose >7.8 mmol/l suggests diabetes 1

Lipid Profile

• Complete fasting lipid panel including total cholesterol, LDL, HDL, and triglycerides is recommended by ACOG for all women with PCOS 1
• Women with PCOS frequently have dyslipidemia with elevated LDL and triglycerides, and decreased HDL 1

Additional Hormonal Tests Based on Clinical Findings

If DHEAS is Elevated

• 17-hydroxyprogesterone with ACTH stimulation testing to rule out non-classical congenital adrenal hyperplasia 2
• This is particularly important if DHEAS exceeds age-specific thresholds 2

If Severe or Rapid-Onset Virilization

• Androstenedione (>10.0 nmol/l suggests adrenal or ovarian tumor) 1
• Immediate adrenal CT imaging if DHEAS >600 μg/dL or signs of severe virilization 2

Gonadotropin Testing

• LH and FSH measured between day 3-6 of the cycle (average of three samples taken 20 minutes apart) 1
• LH/FSH ratio >2 suggests PCOS 1
• FSH >35 IU/l suggests ovarian failure 1
• LH <7 IU/ml suggests hypothalamic amenorrhea 1

Clinical Measurements to Document

• Body mass index (BMI) and waist-hip ratio (WHR) should be calculated 1
• WHR >0.9 indicates truncal obesity and increased metabolic risk 1
• These measurements help stratify cardiovascular and metabolic risk 1

Common Pitfalls to Avoid

• Do not order testosterone post-ictally or without regard to menstrual cycle timing, as this reduces diagnostic accuracy 1
• Do not skip the 2-hour oral glucose tolerance test in favor of fasting glucose alone, as ACOG specifically recommends both for PCOS screening 1
• Do not assume normal testosterone excludes PCOS; some women have isolated anovulation with polycystic ovarian morphology (phenotype D) 1, 3
• Do not delay imaging if DHEAS is markedly elevated (>600 μg/dL), as this may indicate malignancy requiring urgent evaluation 2