What baseline laboratory tests should be ordered for a healthy lactating mother without specific complaints to screen for anemia, iron status, organ function, thyroid function, vitamin D, calcium, phosphorus, folate, vitamin B12, glucose or hemoglobin A1c (if diabetic risk), infectious diseases (HIV, hepatitis B and C, syphilis, HTLV‑1/2) and medication levels if she is taking drugs that pass into breast milk?

Laboratory Testing for Healthy Lactating Mothers

Routine laboratory screening is not recommended for healthy lactating mothers without specific clinical indications or risk factors. 1

Evidence-Based Rationale

The available guidelines do not support routine laboratory testing in asymptomatic, healthy lactating women. The focus should instead be on:

Targeted Testing Based on Clinical Context

• Postpartum glucose screening: Only indicated for women with a history of gestational diabetes mellitus (GDM), who should undergo a 75-gram 2-hour oral glucose tolerance test at 6-12 weeks postpartum to classify glucose metabolism 1

  • Measuring fasting glucose alone misses 66% of women with impaired glucose tolerance or type 2 diabetes postpartum 1
  • Annual fasting glucose and tri-annual glucose tolerance testing thereafter is recommended for women with prior GDM 1

• Infectious disease screening: Not routinely repeated postpartum unless there are new risk factors or the mother was not screened during pregnancy 1

  • All pregnant women should already have been tested for HBsAg during pregnancy 1
  • HCV screening should be universal during pregnancy, not risk-based 1
  • Breastfeeding is not contraindicated even with hepatitis B or C infection 1

Nutritional Considerations Without Routine Testing

The evidence emphasizes dietary adequacy rather than laboratory monitoring for most nutrients:

• Group I nutrients (vitamin A, vitamin D, selenium, iodine): Maternal supplementation directly affects breast milk concentrations and infant status 1

  • Vitamin D supplementation of 10 mcg (400 IU) daily is recommended for all lactating women 1
  • Iodine intake of 200-250 mcg/day is recommended 1

• Group II nutrients (folate, calcium, iron, copper, zinc): Breast milk concentrations are maintained at the expense of maternal stores, but routine testing is not indicated without symptoms 1

  • Folate requirement increases to 500 mcg DFE/day during lactation 1
  • Calcium upper limit is 2,500 mg/day 1

When Laboratory Testing IS Indicated

Test only when specific clinical concerns arise:

• Symptoms of anemia (fatigue, pallor, tachycardia): Check complete blood count and iron studies 1
• Thyroid symptoms (weight changes, fatigue, mood changes): Check thyroid function tests 1
• Diabetes risk factors or prior GDM: Glucose tolerance testing as outlined above 1
• Medication monitoring: Drug levels only if taking medications requiring therapeutic monitoring (e.g., anticonvulsants, lithium) 1, 2
• Persistent postpartum hyperglycemia: Fasting or random capillary glucose before hospital discharge if diabetes during pregnancy 1

Critical Pitfalls to Avoid

• Do not order "routine postpartum labs" without clinical indication—this is not evidence-based and may lead to unnecessary interventions 1
• Do not delay breastfeeding while awaiting test results for infectious diseases if the mother was appropriately screened during pregnancy 1
• Do not assume normal fasting glucose excludes diabetes in women with prior GDM—a full glucose tolerance test is required 1
• Do not routinely check vitamin D or other micronutrient levels—focus on ensuring adequate dietary intake and supplementation instead 1

Practical Approach

For a healthy lactating mother without complaints:

1. Ensure she was appropriately screened during pregnancy for infectious diseases and anemia 1
2. Recommend vitamin D supplementation (10 mcg/400 IU daily) 1
3. Counsel on adequate nutrition including iodine (200-250 mcg/day), folate (500 mcg DFE/day), and calcium (up to 2,500 mg/day) 1
4. If history of GDM: Schedule 75-gram 2-hour OGTT at 6-12 weeks postpartum 1
5. Order laboratory tests only when symptoms or specific risk factors are present 1

The emphasis should be on nutrition counseling and supplementation rather than laboratory surveillance in healthy lactating women. 1