What is the management for a 34-year-old pregnant female with a new pregnancy, last menstrual period (LMP) on [DATE], presenting with leukocyturia (leukocytes in the urine) and elevated Thyroid-Stimulating Hormone (TSH) level of 4.73, indicating hypothyroidism?

Management of Leukocyturia and Elevated TSH in Early Pregnancy

This 34-year-old pregnant woman requires immediate initiation of levothyroxine for hypothyroidism and evaluation/treatment of the urinary tract findings.

Hypothyroidism Management in Pregnancy

Immediate Treatment Indication

• A TSH of 4.73 mIU/L in pregnancy warrants levothyroxine treatment, as pregnancy-specific TSH reference ranges are lower than non-pregnant ranges, and maternal hypothyroidism increases risks of pregnancy complications and impaired fetal cognitive development 1
• All pregnant women with TSH above the trimester-specific reference range should be treated to prevent adverse maternal and neonatal outcomes 2

Levothyroxine Dosing Strategy

For new-onset hypothyroidism with TSH <10 mIU/L in pregnancy:

• Start levothyroxine at 1.0 mcg/kg/day 3
• For a 70 kg woman, this translates to approximately 70 mcg daily, taken on an empty stomach 3

Monitoring schedule:

• Check TSH and free T4 every 4 weeks until TSH is within the normal trimester-specific range 3
• Continue monitoring at minimum once per trimester throughout pregnancy 3
• The goal is to maintain TSH in the trimester-specific reference range (typically 0.1-2.5 mIU/L in first trimester) 3

Dose Adjustments During Pregnancy

• Expect to increase levothyroxine doses during pregnancy - approximately 70% increase may be needed in women with subclinical hypothyroidism 2
• Most patients (86.5%) require one or more dose increases during gestation 2
• Many patients need adjustments beyond the first trimester, with 46.2% requiring changes into the third trimester 2

Postpartum Management

• Reduce levothyroxine to pre-pregnancy levels immediately after delivery 3
• Monitor serum TSH 4 to 8 weeks postpartum 3

Leukocyturia Management

Clinical Significance

• 15 leukocytes/HPF indicates significant pyuria and requires further evaluation for urinary tract infection (UTI), which is common in pregnancy and can lead to serious complications including pyelonephritis and preterm labor

Recommended Approach

• Obtain urine culture to confirm or rule out bacteriuria
• If symptomatic (dysuria, frequency, urgency) or culture-positive, treat with pregnancy-safe antibiotics
• Asymptomatic bacteriuria in pregnancy requires treatment due to high risk of progression to pyelonephritis

Critical Monitoring Considerations

Drug Interactions to Avoid

• Iron and calcium supplements reduce levothyroxine absorption - separate administration by at least 4 hours 4
• Prenatal vitamins containing iron should be taken separately from levothyroxine 4

Signs of Over-Replacement

• Avoid excessive levothyroxine doses, as even slight overdose increases risk of atrial fibrillation and osteoporotic fractures 4
• Monitor for thyrotoxic symptoms: tachycardia, tremor, excessive sweating 4

Timing of Laboratory Assessment

• TSH levels require 6-8 weeks to stabilize after any dose change due to levothyroxine's long half-life 3
• Do not adjust doses more frequently than every 6 weeks unless clinically indicated 3