How should levothyroxine be titrated in an adult taking 150 µg daily with a TSH of 11.5 mIU/L?

Levothyroxine Dose Adjustment for TSH 11.5 mIU/L

Increase your levothyroxine dose by 25 µg (from 150 µg to 175 µg daily) and recheck TSH in 6–8 weeks. 1

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Why This Dose Adjustment Is Necessary

Your current TSH of 11.5 mIU/L indicates inadequate thyroid hormone replacement despite taking 150 µg daily 1. This level of TSH elevation carries approximately 5% annual risk of progression to overt hypothyroidism and is associated with adverse cardiovascular effects including delayed myocardial relaxation, abnormal cardiac output, and unfavorable lipid profiles 1. Treatment at this TSH threshold is recommended regardless of symptoms because the risks of undertreatment outweigh the risks of dose adjustment 1.

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Specific Dose Adjustment Protocol

Standard Increment

• Increase by 12.5–25 µg based on your current dose and clinical characteristics 1
• For a patient on 150 µg with TSH >10 mIU/L, a 25 µg increment is appropriate (moving to 175 µg daily) 1
• Larger adjustments risk iatrogenic hyperthyroidism and should be avoided 1

Age and Cardiac Considerations

• If you are >70 years old or have cardiac disease: use the smaller 12.5 µg increment to avoid unmasking cardiac ischemia or precipitating arrhythmias 1
• If you are <70 years without cardiac disease: the 25 µg increment is safe and allows faster normalization 1

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Monitoring Timeline

• Recheck TSH and free T4 in 6–8 weeks after the dose change, as this is the time required for levothyroxine to reach steady state 1, 2
• Target TSH range: 0.5–4.5 mIU/L with normal free T4 1
• Continue adjusting by 12.5–25 µg increments every 6–8 weeks until TSH normalizes 1
• Once stable, monitor TSH every 6–12 months or sooner if symptoms change 1

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Critical Safety Considerations

Rule Out Adrenal Insufficiency First

• Before increasing levothyroxine, especially if you have suspected central hypothyroidism or are on immunotherapy, measure morning cortisol and ACTH 1
• Starting or increasing thyroid hormone before adequate corticosteroid coverage can precipitate life-threatening adrenal crisis 1
• If adrenal insufficiency is present, start hydrocortisone at least one week before increasing levothyroxine 1

Confirm Persistent Elevation

• Repeat TSH and free T4 after 3–6 weeks if this is your first elevated result, as 30–60% of elevated TSH values normalize spontaneously 1, 3
• However, a TSH of 11.5 mIU/L is high enough that treatment is warranted even without waiting for confirmation if you are symptomatic 1

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Administration Instructions

• Take levothyroxine on an empty stomach, 30–60 minutes before breakfast, with a full glass of water 2
• Wait at least 4 hours before taking iron, calcium supplements, or antacids, as these interfere with absorption 2
• Avoid soybean-based foods near the time of administration 2
• Switching to evening dosing (before dinner) reduces therapeutic efficacy and is not recommended 4

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Common Pitfalls to Avoid

Do Not Over-Adjust

• Avoid jumping to full replacement dose (e.g., 200+ µg), as this risks iatrogenic hyperthyroidism 1
• Approximately 25% of patients on levothyroxine are unintentionally overtreated, leading to suppressed TSH and increased risks of atrial fibrillation, osteoporosis, and fractures 1

Do Not Adjust Too Frequently

• Wait the full 6–8 weeks between dose changes to allow steady state 1
• Adjusting doses before steady state leads to inappropriate titration 1

Do Not Ignore Transient Causes

• Exclude reversible factors before increasing dose: recent severe illness, recovery from thyroiditis, iodine exposure (e.g., CT contrast), or medications (lithium, amiodarone, interferon) 1
• If any of these are present, recheck TSH after resolution before adjusting dose 1

Do Not Treat Based on Single Result

• If this is your first elevated TSH, confirm with repeat testing unless you are symptomatic or TSH is very high (>10 mIU/L) 1, 3

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Special Populations Requiring Modified Approach

Elderly or Cardiac Disease

• Start with 12.5 µg increment (to 162.5 µg daily) rather than 25 µg 1
• Monitor closely for angina, palpitations, or worsening heart failure 1
• Consider obtaining an ECG to screen for baseline arrhythmias 1

Pregnancy or Planning Pregnancy

• More aggressive normalization is warranted, targeting TSH <2.5 mIU/L in the first trimester 1
• Levothyroxine requirements typically increase by 25–50% during pregnancy 1
• Check TSH every 4 weeks until stable, then at minimum once per trimester 1

Positive Anti-TPO Antibodies

• If you have positive anti-thyroid peroxidase antibodies, your annual progression risk to overt hypothyroidism is 4.3% (vs 2.6% without antibodies) 1
• This supports more aggressive treatment at lower TSH thresholds 1

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Expected Outcomes

• Symptom improvement (if present) should occur within 6–8 weeks of achieving target TSH 1
• Cardiovascular function improves with normalization of TSH, including resolution of delayed myocardial relaxation and abnormal cardiac output 1
• LDL cholesterol may decrease with adequate treatment 1

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When to Seek Urgent Evaluation

• New or worsening chest pain, severe shortness of breath, or marked ankle swelling may signal progression to severe hypothyroidism requiring prompt treatment 1
• Severe fatigue preventing routine activities warrants earlier follow-up 1