Can anemia cause headache and blurry vision in a pregnant patient?

Can Anemia Cause Headache and Blurry Vision in Pregnancy?

Yes, anemia can cause headache and blurry vision in pregnant patients, though these symptoms warrant immediate evaluation to distinguish between common iron deficiency manifestations and potentially serious complications requiring urgent intervention.

Understanding the Mechanism

Iron deficiency affects neurocognitive function and causes mood disturbances through alterations in serotonin, norepinephrine, and dopamine levels, and these symptoms can occur even before hemoglobin drops below diagnostic thresholds for anemia 1. This means a pregnant patient can experience neurological symptoms including headache from iron deficiency without meeting formal anemia criteria.

Critical Distinction: When Vision Changes Signal Danger

Severe Anemia with Vision Loss

• If hemoglobin is <7.0 g/dL, refer immediately for medical evaluation 2, 3
• Severe anemia (hemoglobin 4.0-6.9 g/dL) or moderate anemia (hemoglobin 7.0-9.9 g/dL) requires further investigation beyond presumptive iron deficiency 4
• Case reports document that severe aplastic anemia in pregnancy can cause bilateral disc edema and acute pre-retinal hemorrhage leading to vision loss, which resolved with supportive transfusions 5

Diabetic Retinopathy Considerations

While the evidence provided focuses on diabetic retinopathy screening 2, this is not directly relevant to anemia-related visual symptoms in non-diabetic pregnant patients. However, if your patient has pre-existing diabetes, rapid worsening of retinopathy can occur during pregnancy and requires ophthalmologic evaluation 2.

Diagnostic Approach

Initial Screening

• Screen for anemia at the first prenatal visit using hemoglobin or hematocrit 2
• Use pregnancy-specific thresholds: <11.0 g/dL in first trimester, <10.5-11.0 g/dL in second/third trimester 4
• Remember that 18.6% of pregnant women have iron deficiency, but only 16.2% also have anemia, meaning standard hemoglobin/hematocrit screening may miss iron deficiency without anemia 1

When to Investigate Further

• Hemoglobin <9.0 g/dL: Refer to physician familiar with anemia in pregnancy 2
• Mild anemia with very low MCV, macrocytic anemia, or failure to respond to iron after 4 weeks: Obtain additional tests including MCV, RDW, and serum ferritin 2, 4
• In women of African, Mediterranean, or Southeast Asian ancestry, consider thalassemia minor or sickle cell trait if unresponsive to iron 2

Treatment Algorithm

For Confirmed or Presumptive Iron Deficiency Anemia

1. Start oral iron 60-120 mg elemental iron daily 2, 4
2. Counsel on iron-rich foods and foods that enhance iron absorption 2
3. Reassess after 4 weeks: Expect hemoglobin increase of 1 g/dL or hematocrit increase of 3% 2
4. If no response despite compliance and absence of acute illness, further evaluate 2
5. Once hemoglobin normalizes for gestational stage, decrease to 30 mg/day 2

For Iron Deficiency Without Anemia

Current ACOG guidelines do not recommend treating iron deficiency without anemia during pregnancy, though this remains an area of ongoing research 6. However, given that impaired neurocognitive function and mood disturbances occur with iron deficiency before anemia develops 1, consider treatment if symptoms are present.

For Severe Cases

• Intravenous iron is preferred for patients who cannot tolerate, cannot absorb, or do not respond to oral iron 4
• Contemporary IV iron formulations have rare allergic reactions 4

Common Pitfalls to Avoid

• Don't dismiss symptoms in early pregnancy: Physiologic hemodilution occurs, but symptoms suggest pathologic anemia 7
• Don't assume all anemia is iron deficiency: 75% of pregnancy anemia is iron deficiency, but 25% has other causes 8, 6
• Don't overlook high hemoglobin: Hemoglobin >15.0 g/dL or hematocrit >45.0% in second/third trimester indicates poor blood volume expansion and warrants evaluation for pregnancy complications 2, 7
• Don't delay ophthalmologic referral: If blurry vision is accompanied by severe anemia, floaters, or sudden vision loss, this requires urgent evaluation 5

Maternal and Fetal Implications

Severe anemia (hemoglobin <6 g/dL) is associated with poor pregnancy outcomes including prematurity, spontaneous abortions, low birth weight, and fetal deaths 8. Maternal anemia also increases the likelihood of transfusion at delivery 4. Both iron deficiency with and without anemia are associated with impaired neurocognitive development in children and suboptimal immune responses 1.