What is the next step for a patient with a Thyroid-Stimulating Hormone (TSH) level of 23, currently medicating with Synthroid (levothyroxine) 88 mcg?

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Last updated: November 7, 2025View editorial policy

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Management of Inadequately Controlled Hypothyroidism

Increase the levothyroxine dose by 12.5-25 mcg immediately, as a TSH of 23 mIU/L on 88 mcg indicates severe undertreatment requiring urgent dose adjustment. 1

Immediate Action Required

Your current dose of 88 mcg is clearly insufficient. A TSH level of 23 mIU/L represents overt hypothyroidism despite treatment, carrying significant risks for cardiovascular dysfunction, metabolic abnormalities, and impaired quality of life. 1

Recommended Dose Adjustment

  • Increase levothyroxine by 25 mcg to 112-113 mcg daily (the standard increment for patients with TSH >10 mIU/L). 1, 2
  • If you are over 70 years old or have cardiac disease, use a more conservative 12.5 mcg increment instead. 1, 2
  • For younger patients without cardiac disease, the 25 mcg increase is appropriate and necessary given the severity of TSH elevation. 1

Monitoring Timeline

  • Recheck TSH and free T4 in exactly 6-8 weeks after the dose increase—not sooner, as steady-state levels require this time frame. 1, 2
  • If you have atrial fibrillation or serious cardiac disease, consider rechecking within 2 weeks instead. 1
  • Continue adjusting the dose every 6-8 weeks until TSH normalizes to 0.5-4.5 mIU/L. 1, 2

Critical Issues to Address

Rule Out Medication Adherence Problems

  • Poor compliance is the most common cause of persistently elevated TSH in treated patients. 3
  • Take levothyroxine on an empty stomach, 30-60 minutes before breakfast, with a full glass of water. 4
  • Avoid taking it within 4 hours of calcium supplements, iron, or antacids, which significantly impair absorption. 4

Check for Malabsorption

If TSH remains elevated despite confirmed adherence and appropriate dose increases, consider: 5, 3

  • Celiac disease, inflammatory bowel disease, or atrophic gastritis
  • Proton pump inhibitor use (reduces acid needed for tablet dissolution)
  • Recent bariatric surgery
  • Switching to liquid levothyroxine formulation may overcome absorption issues. 6

Review Drug Interactions

Common medications that increase levothyroxine requirements include: 5, 3

  • Estrogen therapy or oral contraceptives
  • Rifampin, carbamazepine, phenytoin
  • Proton pump inhibitors
  • Bile acid sequestrants

Why This TSH Level Demands Urgent Treatment

  • TSH >10 mIU/L carries approximately 5% annual risk of progression to severe overt hypothyroidism. 1
  • At TSH 23, you already have severe overt hypothyroidism causing: 1, 7
    • Adverse cardiovascular effects (delayed relaxation, abnormal cardiac output)
    • Elevated LDL cholesterol
    • Persistent hypothyroid symptoms (fatigue, weight gain, cold intolerance, constipation)
    • Significantly impaired quality of life

Target Goal

  • Aim for TSH between 0.5-4.5 mIU/L with normal free T4 levels. 1, 2
  • Once stable, monitor TSH annually (or every 6-12 months). 1, 2

Common Pitfall to Avoid

  • Do not make small, timid dose adjustments—a TSH of 23 requires meaningful intervention, not incremental tinkering. 1
  • Do not adjust doses more frequently than every 6-8 weeks, as levothyroxine takes this long to reach steady state. 1, 2
  • About 25% of patients on levothyroxine are inadvertently under- or over-treated, emphasizing the need for proper monitoring. 1

Special Consideration

If you have thyroid cancer requiring TSH suppression, this TSH level is still far too high—even cancer patients rarely need TSH >10 mIU/L. 2 However, standard hypothyroidism treatment aims for normal-range TSH, not suppression. 2

References

Guideline

Initial Treatment for Elevated TSH

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

Guideline

Levothyroxine Dosing and Counseling Guidelines

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

Research

Hypothyroidism: Diagnosis and Treatment.

American family physician, 2021

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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