Fatigue Workup in Childbearing Women: Not a Fishing Trip

Four tests. That’s the starting line: CBC, ferritin, TSH, pregnancy test. Not a 30-tube rainbow draw.

“I'm just so tired all the time.” It's one of the most common complaints in primary care, and in women of childbearing age, the differential is simultaneously broad and predictable. The temptation is to order everything—a CMP, CBC, iron studies, B12, folate, vitamin D, cortisol, ANA, Lyme, EBV, celiac panel, ferritin, TSH, free T4, testosterone—and hope something lights up. That's not a workup. That's a fishing trip. And fishing trips catch incidental abnormalities that generate more tests, more anxiety, and no answers.

This post makes the case for a disciplined, stepwise approach.

The Core Four: Start Here, Every Time

The First-Line Panel

1. CBC: Anemia is the most common lab-identifiable cause of fatigue in this population. Look at hemoglobin AND MCV (microcytic = iron deficiency until proven otherwise).
2. Ferritin: Iron deficiency causes fatigue before anemia develops. A normal hemoglobin does NOT rule out iron deficiency. Ferritin is the test that catches the pre-anemic state.
3. TSH: Hypothyroidism is common in women of reproductive age. One test, high yield.
4. Pregnancy test (urine hCG): Fatigue is often the first symptom of early pregnancy, before a missed period is noticed. In any woman of childbearing age with new-onset fatigue, rule it out. It changes everything about your workup and management.

These four tests cover the most common and most treatable causes of fatigue in this population. If all four are normal, then you expand.

Iron Deficiency Without Anemia: The Under-Recognized Entity

This is the clinical pearl that separates a good fatigue workup from a mediocre one. Iron deficiency exists on a spectrum:

• Stage 1: Depleted iron stores (low ferritin, normal hemoglobin, normal MCV). The patient is symptomatic—fatigued, brain fog, exercise intolerance, restless legs—but the CBC is “normal.”
• Stage 2: Iron-deficient erythropoiesis (low ferritin, low transferrin saturation, normal or borderline hemoglobin, possibly low MCV)
• Stage 3: Iron deficiency anemia (low ferritin, low hemoglobin, low MCV, microcytic hypochromic RBCs on smear)

If you only check a CBC and the hemoglobin is 12.5, you'll call it normal and send the patient home. But her ferritin might be 8. She has iron deficiency without anemia—and she'll feel dramatically better with iron replacement.

The Ferritin Threshold Debate

What ferritin level defines iron deficiency? This is more contentious than it should be.

• WHO/traditional cutoff: Ferritin <15 ng/mL = iron deficiency
• Most hematologists and current evidence: Ferritin <30 ng/mL = iron deficiency in the context of symptoms
• Functional iron deficiency (especially with inflammation): Ferritin <100 ng/mL with transferrin saturation <20% may indicate iron deficiency despite “normal” ferritin (ferritin is an acute phase reactant)

For a symptomatic woman of childbearing age, ferritin <30 should be treated as iron deficiency. Multiple RCTs have demonstrated symptom improvement with iron supplementation in non-anemic women with ferritin <50, particularly for fatigue and cognitive function.

When the Core Four Are Normal: Expanding the Workup

Tier 2 (If Core Four Are Normal and Fatigue Persists >4 Weeks)

• BMP: Electrolyte abnormalities (hyponatremia, hypercalcemia), renal insufficiency, glucose (diabetes or hypoglycemia)
• Vitamin D: Deficiency is endemic but its role in fatigue is debated. Check it, but manage expectations—correcting vitamin D may or may not resolve fatigue.
• Depression screening (PHQ-9): This should arguably be Tier 1. Depression and fatigue are intimately linked, and no lab test diagnoses depression. If the PHQ-9 is positive, treat the depression.
• Sleep history: Obstructive sleep apnea is underdiagnosed in women. Ask about snoring, witnessed apneas, morning headaches. STOP-BANG questionnaire.

Tier 3 (If Tier 2 Normal and Specific Symptoms Suggest)

• Celiac panel (tTG-IgA + total IgA): If GI symptoms, iron-refractory iron deficiency, or family history
• ANA: Only if joint pain, rash, photosensitivity, or other autoimmune features are present. Do NOT order ANA as a fishing expedition—the false positive rate in young women is high, and it generates referrals and anxiety without answers.
• Cortisol (AM): Only if Addisonian features (orthostasis, hyperpigmentation, salt craving, weight loss)
• EBV panel: Only if acute-onset fatigue with pharyngitis, lymphadenopathy, splenomegaly. Chronic EBV is not a validated diagnosis; don't order it for chronic fatigue.
• B12/MMA: Lower yield in this population (more relevant for elderly, vegans, post-bariatric surgery)

What NOT to Order (and Why)

Choosing Wisely for Fatigue

• Lyme titers in non-endemic areas: False positives abound. Only test if exposure history + clinical features support it.
• EBV titers for chronic fatigue: Most adults are EBV seropositive. A positive IgG means past exposure, not active disease. It doesn't explain chronic fatigue.
• ANA without autoimmune features: Up to 20% of healthy young women have low-titer positive ANA. A positive ANA without clinical findings generates rheumatology referrals that end with “no autoimmune disease.”
• Morning cortisol without Addisonian features: Random cortisol testing for fatigue has extremely poor specificity. Adrenal insufficiency is rare; poor sleep, depression, and iron deficiency are common.
• Testosterone levels in premenopausal women: Not validated as a fatigue workup tool in this population.
• “Adrenal fatigue” panels: This is not a recognized medical diagnosis. Salivary cortisol panels marketed for “adrenal fatigue” are not evidence-based.

When Labs Are Normal: What Then?

If the Core Four are normal, depression is screened for, sleep is addressed, and Tier 2 labs are unrevealing, the most common diagnoses remaining are:

• Depression/anxiety (may need formal psychiatric evaluation if PHQ-9 doesn't capture it)
• Sleep deprivation (the most undertreated cause of fatigue in working mothers)
• Obstructive sleep apnea (consider sleep study)
• Chronic fatigue syndrome / ME/CFS: Diagnosis of exclusion. Requires ≥6 months of unexplained fatigue + post-exertional malaise + unrefreshing sleep. Validate the patient's experience.
• Lifestyle factors: Overcommitment, caregiving burden, inadequate nutrition, deconditioning

The most important thing at this stage is to believe the patient. “Your labs are normal” doesn't mean “you're fine.” It means the labs didn't find the answer. The fatigue is real.

Iron Replacement: Practical Notes

• Oral iron: Ferrous sulfate 325 mg (65 mg elemental iron) every other day is better absorbed than daily (hepcidin rebound with daily dosing). Take with vitamin C, empty stomach, avoid calcium/coffee/tea within 2 hours.
• IV iron: Consider for ferritin <15 with Hgb <10, oral intolerance, malabsorption (celiac, IBD, bariatric surgery), second/third trimester pregnancy with significant anemia, or failure to respond to 4–6 weeks of oral iron.
• Recheck ferritin at 8–12 weeks. Goal: ferritin >50 (some argue >100 for sustained repletion).
• Identify the source: Heavy menstrual bleeding is the most common cause of iron deficiency in this population. Screen with pictorial bleeding assessment chart (PBAC) or menstrual history. If HMB is present, treat the bleeding (hormonal management, referral to GYN) in addition to replacing iron.

Bottom Line

Fatigue in childbearing women is best approached with discipline, not a shotgun. Start with CBC, ferritin, TSH, and a pregnancy test. Ferritin <30 in a symptomatic woman is iron deficiency regardless of hemoglobin. If the Core Four are normal, screen for depression and sleep disorders before adding labs. Don't order ANA, EBV, or cortisol without specific clinical indications. And when all the labs come back normal, the fatigue is still real—acknowledge it, investigate further, and keep advocating for your patient.

Stay sharp out there.

 

Pap Smear Interpretation: Bethesda Classification, HPV Co-Testing, and the ASCCP Management Guidelines

ASC-US with negative HPV? Routine screening. AGC? Colposcopy, endocervical curettage, and possibly endometrial biopsy. Know the difference.

Cervical cancer screening has evolved dramatically, yet the interpretation of results and management algorithms remain a source of confusion for many providers. The shift from cytology-only screening to HPV co-testing and primary HPV screening has changed when and how we act on results. This post walks through the Bethesda classification system, the current screening strategies, and the 2019 ASCCP risk-based management consensus guidelines.

Current Screening Strategies

Age Group	Preferred Strategy	Acceptable Alternatives	Interval
<21 years	No screening (regardless of sexual activity or HPV vaccination status)	None	N/A
21–24 years	Cytology (Pap) alone	No HPV testing in this age group (too many transient infections)	Every 3 years
25–65 years	Primary HPV testing alone (FDA-approved tests) every 5 years	HPV + cytology co-testing every 5 years, OR cytology alone every 3 years	See strategy
>65 years	Discontinue if adequate prior screening and no history of CIN2+	Adequate = 3 consecutive negative cytology or 2 consecutive negative co-tests in prior 10 years, most recent within 5 years	N/A
Post-hysterectomy (total, with cervix removed)	No screening if no history of CIN2+ and the hysterectomy was for benign indications	Continue screening if history of CIN2+ (screen for 25 years after treatment)	N/A

The Primary HPV Shift

The ACS (2020) and USPSTF (2018) now endorse primary HPV testing as the preferred strategy for ages 25–65. This means HPV testing alone—without concurrent cytology—as the first-line screen. If the HPV test is positive, reflex cytology (triage Pap) is performed on the same specimen. This approach has higher sensitivity for CIN3+ than cytology alone. The key HPV genotypes to know: HPV 16 and HPV 18 are highest risk and warrant direct colposcopy referral even with normal cytology.

The Bethesda Classification System

Result	Full Name	What It Means	Management Summary
NILM	Negative for Intraepithelial Lesion or Malignancy	Normal. May note benign findings (inflammation, atrophy, reactive changes).	Return to routine screening per age-appropriate interval.
ASC-US	Atypical Squamous Cells of Undetermined Significance	Mildly abnormal cells that could be reactive or low-grade. Most common abnormal result.	Reflex HPV testing. If HPV(+): colposcopy. If HPV(−): return in 3 years (co-test) or 5 years (primary HPV).
ASC-H	Atypical Squamous Cells, cannot exclude HSIL	More concerning than ASC-US; higher likelihood of underlying CIN2/3.	Colposcopy regardless of HPV status.
LSIL	Low-grade Squamous Intraepithelial Lesion	Equivalent to CIN1/HPV effect. Most regress spontaneously, especially in young women.	Ages 21–24: repeat cytology in 1 year. Ages ≥25: colposcopy (per ASCCP guidelines, management mirrors ASC-US HPV+).
HSIL	High-grade Squamous Intraepithelial Lesion	Equivalent to CIN2/3. Significant precancer risk.	Expedited treatment (LEEP) or colposcopy depending on age and risk factors. Non-pregnant, ≥25, not concerned about fertility: immediate LEEP is acceptable.
AGC	Atypical Glandular Cells	Abnormal glandular cells. Can originate from endocervix OR endometrium. Higher risk of significant pathology than ASC-US.	Colposcopy + endocervical curettage (ECC) for ALL. Add endometrial biopsy if ≥35 years, abnormal uterine bleeding at any age, or AGC “favor neoplasia.”
AIS	Adenocarcinoma In Situ	Glandular precancer of the endocervix.	Colposcopy + ECC + diagnostic excision. Hysterectomy is the definitive treatment for completed childbearing.
SCC / Adenocarcinoma	Squamous Cell Carcinoma / Adenocarcinoma	Invasive cancer on cytology.	Urgent referral to gynecologic oncology.

AGC Is Never Routine

AGC (Atypical Glandular Cells) is the result that demands the most aggressive workup relative to how benign it sounds. Unlike ASC-US, which is usually nothing, AGC carries a 9–38% risk of significant pathology (CIN2+, AIS, or endometrial pathology). Every AGC result requires colposcopy with endocervical curettage. In women ≥35 or with abnormal uterine bleeding, add endometrial biopsy. AGC “favor neoplasia” carries the highest risk and may require diagnostic excisional procedure even if colposcopy is negative.

The ASC-US Reflex Algorithm

ASC-US is the most common abnormal Pap result and accounts for the majority of follow-up decisions in primary care. The reflex HPV test (run on the same specimen) is the triage tool:

• ASC-US + HPV negative: Return to routine screening (every 3 years with co-testing, or every 5 years with primary HPV). The negative HPV essentially rules out significant disease.
• ASC-US + HPV positive (not 16/18): Repeat co-testing in 1 year. If persistent ASC-US/HPV+ or worse, colposcopy.
• ASC-US + HPV 16 or HPV 18 positive: Proceed directly to colposcopy. HPV 16/18 carry the highest CIN3+ risk.

The 2019 ASCCP Risk-Based Management Guidelines

The Paradigm Shift

The 2019 ASCCP guidelines moved from result-based management (same result = same action) to risk-based management (same result + different history = different action). The key principle: management is determined by the patient's estimated risk of CIN3+ based on current results AND prior screening history. Two patients with LSIL may be managed differently if one has a history of normal screens (lower risk) and the other has prior ASC-US (higher risk). Use the ASCCP management guidelines app or risk tables at asccp.org.

Special Populations

Ages 21–24

HPV is extremely common and usually transient in this age group. Management is more conservative: ASC-US and LSIL are managed with repeat cytology in 1 year, not immediate colposcopy. HSIL still warrants colposcopy. No HPV co-testing (high false positive rate from transient infections).

Pregnancy

Colposcopy can be performed during pregnancy (no endocervical curettage). Treatment (LEEP, excision) is deferred until postpartum unless invasive cancer is suspected. Cervical biopsy is acceptable during pregnancy if indicated by colposcopic findings.

Immunocompromised (HIV+)

Start screening at age 21 (within 1 year of sexual debut for HIV+). Screen annually with cytology (21–29) or co-testing (30+). After 3 consecutive normal results, can extend to every 3 years. Never stop screening (no age cutoff). HPV persistence and progression are more common.

Post-HPV Vaccination

Vaccinated individuals follow the same screening guidelines as unvaccinated. The vaccine doesn't cover all high-risk HPV types, and patients may have been exposed before vaccination. Screening intervals and management don't change.

The Pitfalls

• Don't Pap women under 21: No exceptions. Even with sexual activity, HPV exposure, or abnormal symptoms. If symptomatic, evaluate the symptoms—don't screen for cervical cancer.
• Don't HPV-test women 21–24: Transient HPV is ubiquitous in this age group. A positive HPV in a 22-year-old causes anxiety and overtesting with no benefit.
• AGC is not ASC-US: The workup is fundamentally different. AGC always needs colposcopy + ECC. Don't just repeat the Pap.
• Post-hysterectomy screening errors: If the cervix was removed for benign indications and there's no CIN2+ history, screening is over. If the cervix was NOT removed (supracervical hysterectomy), screening continues.
• Don't over-screen: Co-testing every year is not indicated for normal-risk patients. It leads to false positives and unnecessary colposcopies. Stick to the recommended intervals.
• Inadequate specimen: An “unsatisfactory” Pap needs to be repeated in 2–4 months, not in a year. Don't let it fall through the cracks.

Bottom Line

Cervical cancer screening saves lives when done correctly—at the right intervals, with the right tests, and with appropriate follow-up. Primary HPV testing is the preferred strategy for 25–65. ASC-US with negative HPV is reassuring. AGC is never reassuring. HPV 16/18 positivity warrants colposcopy regardless of cytology. And the 2019 ASCCP guidelines mean that a patient's screening history now drives management, not just the current result. Use the ASCCP risk tables and manage accordingly.

Stay sharp out there.