What is the best course of action for a patient with a Thyroid-Stimulating Hormone (TSH) level of 7.23 mU/L, who is currently taking 137 mcg of Synthroid (levothyroxine), indicating uncontrolled hypothyroidism?

Increase Levothyroxine Dose Immediately

Your TSH of 7.23 mU/L while taking 137 mcg of Synthroid indicates inadequate thyroid hormone replacement and requires a dose increase to prevent cardiovascular complications, worsening symptoms, and progression to overt hypothyroidism. 1

Why Your Current Dose Is Insufficient

• A TSH of 7.23 mU/L is clearly elevated above the normal reference range of 0.45-4.5 mU/L, indicating your body is not receiving adequate thyroid hormone despite treatment 1
• Persistent TSH elevation >7 mU/L carries approximately 5% annual risk of progression to overt hypothyroidism and is associated with adverse cardiovascular effects, abnormal lipid metabolism, and reduced quality of life 1
• Even for patients already on levothyroxine therapy, TSH levels in this range require dose adjustment to normalize thyroid function and prevent complications 1

Recommended Dose Adjustment

Increase your Synthroid dose by 12.5-25 mcg based on your current dose of 137 mcg. 1

• For a patient taking 137 mcg daily, a 12.5 mcg increment (to 150 mcg) is appropriate as the first adjustment 1
• Larger dose increases may lead to overtreatment and should be avoided, especially if you are elderly or have cardiac disease 1
• If you are under 70 years old without cardiac disease, a 25 mcg increment (to 162.5 mcg or rounding to 150 mcg) may be appropriate for more aggressive titration 1

Monitoring After Dose Adjustment

• Recheck TSH and free T4 in 6-8 weeks after the dose increase, as this represents the time needed to reach steady state 1
• Target TSH should be within the reference range of 0.5-4.5 mU/L with normal free T4 levels 1
• Continue dose adjustments by 12.5-25 mcg increments every 6-8 weeks as needed until TSH normalizes 1
• Once adequately treated, repeat testing every 6-12 months or if symptoms change 1

Critical Considerations Before Increasing Dose

Before increasing levothyroxine, rule out medication non-adherence, as this is the most common cause of elevated TSH in treated patients. 2

• Confirm you are taking levothyroxine on an empty stomach, 30-60 minutes before breakfast, and at least 4 hours apart from iron, calcium supplements, or antacids 1
• Verify you are not taking medications that interfere with levothyroxine absorption, such as proton pump inhibitors, iron supplements, calcium, or bile acid sequestrants 3
• Ensure you have not recently been hospitalized or had acute illness, as these can transiently elevate TSH 1

Special Populations Requiring Modified Approach

If you are over 70 years old or have cardiac disease, use a smaller 12.5 mcg increment to avoid potential cardiac complications. 1

• Elderly patients and those with underlying coronary disease are at increased risk of cardiac decompensation, angina, or arrhythmias even with therapeutic levothyroxine doses 1
• Start with conservative dose increases and monitor closely for chest pain, palpitations, or worsening heart failure 1

If you are pregnant or planning pregnancy, more aggressive TSH normalization is warranted, targeting TSH <2.5 mU/L in the first trimester. 1

• Untreated or inadequately treated hypothyroidism during pregnancy increases risk of preeclampsia, low birth weight, and neurodevelopmental effects in the offspring 1
• Levothyroxine requirements typically increase by 25-50% during pregnancy 1

Common Pitfalls to Avoid

• Do not wait to increase the dose. TSH >7 mU/L represents inadequate replacement that is already causing metabolic consequences 1
• Do not adjust doses too frequently before reaching steady state. Wait the full 6-8 weeks between adjustments 1
• Do not assume symptoms are unrelated to hypothyroidism. Persistent TSH elevation causes fatigue, weight gain, cold intolerance, constipation, and cognitive impairment that will improve with adequate treatment 1
• Avoid excessive dose increases that could lead to iatrogenic hyperthyroidism. This increases risk for atrial fibrillation, osteoporosis, fractures, and cardiac complications 1

Long-Term Management

• Once TSH is stabilized in the normal range (0.5-4.5 mU/L), annual testing is sufficient unless symptoms change 1
• Approximately 25% of patients on levothyroxine are unintentionally maintained on doses that either suppress or fail to normalize TSH, highlighting the importance of regular monitoring 1
• Development of low TSH (<0.1-0.45 mU/L) on therapy suggests overtreatment and requires dose reduction 1