Treatment for Pregnant Women with Iron Deficiency and Hypothyroidism
Pregnant women with both iron deficiency anemia and hypothyroidism should be treated with levothyroxine to normalize TSH levels and 60-120 mg/day of oral iron supplementation for anemia, with regular monitoring of both conditions throughout pregnancy. 1
Management of Hypothyroidism in Pregnancy
- Hypothyroidism in pregnant women should be treated with levothyroxine in a sufficient dosage to return the TSH level to normal 1
- The levothyroxine dosage should be adjusted every four weeks until the TSH level is stable 1
- TSH levels should be checked every trimester to ensure adequate treatment 1
- Untreated maternal hypothyroidism increases the risk of preeclampsia and is associated with low birth weight in neonates 1
- Inadequate treatment of hypothyroidism from iron deficiency increases the risk of congenital cretinism (growth failure, mental retardation, and other neuropsychologic defects) 1
Management of Iron Deficiency in Pregnancy
- For established iron deficiency anemia in pregnancy, prescribe 60-120 mg/day of oral elemental iron 1, 2
- Start with oral iron supplementation as the first-line treatment for iron deficiency anemia in pregnancy 3
- Continue iron treatment until hemoglobin concentration becomes normal for the stage of gestation, then decrease the dose to 30 mg/day 1
- Counsel pregnant women about consuming iron-rich foods and foods that enhance iron absorption 1
Monitoring and Follow-up
- Monitor response to iron therapy after 4 weeks of treatment; hemoglobin should increase by 1 g/dL or hematocrit by 3% 1
- If anemia does not respond to iron treatment despite compliance, further evaluate with additional tests including MCV, RDW, and serum ferritin concentration 1
- For severe anemia (Hb <9.0 g/dL or Hct <27.0%), refer the patient to a physician familiar with anemia during pregnancy 1
- Continue monitoring TSH levels throughout pregnancy to ensure adequate thyroid hormone replacement 1
Special Considerations and Potential Pitfalls
- Iron deficiency can worsen hypothyroidism as iron is an essential cofactor for thyroid peroxidase (TPO), which is necessary for thyroid hormone synthesis 4
- Women with chronic energy deficiency (CED) may have a higher risk of hypothyroidism when iron deficient 4
- Consider the timing of iron and levothyroxine administration - iron supplements can interfere with levothyroxine absorption, so separate these medications by at least 4 hours 5
- Side effects of iron supplementation (constipation, nausea) may overlap with pregnancy symptoms and hypothyroidism symptoms, making it difficult to distinguish between them 3, 6
- For women with compliance issues due to side effects, consider alternate-day dosing of iron, which may have similar efficacy with potentially fewer side effects 6
- Vegetarian women may require higher iron supplementation doses due to lower absorption of non-heme iron 2, 5