How do I restart levothyroxine in an adult with severe hypothyroidism (markedly elevated TSH) after stopping a 137 µg dose several months ago, now presenting with a goiter and symptoms?

Restarting Levothyroxine in Severe Hypothyroidism After Non-Adherence

Immediate Restart Strategy

Restart levothyroxine immediately at the patient's previous dose of 137 mcg daily, as this represents their established maintenance requirement and the severely elevated TSH (211,000 mIU/L) with symptomatic presentation (goiter, hypothyroid symptoms) indicates life-threatening overt hypothyroidism requiring urgent full replacement. 1, 2

Critical Safety Assessment Before Restarting

Before administering the first levothyroxine dose, you must exclude adrenal insufficiency by measuring morning (8 AM) cortisol and ACTH levels, because initiating thyroid hormone in unrecognized adrenal insufficiency can precipitate fatal adrenal crisis. 1, 3 If morning cortisol is low or clinical features suggest adrenal insufficiency (hypotension, hyponatremia, unexplained symptoms), start hydrocortisone 20 mg morning and 10 mg afternoon for at least one week before levothyroxine. 1

Dosing Algorithm

• For patients under 70 years without cardiac disease: Restart at the full previous dose of 137 mcg daily immediately, as young patients tolerate rapid normalization and the TSH of 211,000 indicates months of severe deficiency requiring aggressive replacement. 1, 2

• For patients over 70 years OR with any cardiac disease (coronary disease, heart failure, atrial fibrillation): Start conservatively at 25-50 mcg daily despite the previous 137 mcg dose, because rapid thyroid hormone replacement can unmask cardiac ischemia, precipitate myocardial infarction, or trigger life-threatening arrhythmias in this population. 1, 2, 4 Increase by 12.5-25 mcg every 6-8 weeks based on TSH response. 1, 2

Administration Instructions

• Take levothyroxine as a single daily dose on an empty stomach, one-half to one hour before breakfast with a full glass of water. 2

• Administer at least 4 hours before or after drugs that interfere with absorption (iron, calcium, proton pump inhibitors, bile acid sequestrants). 2

• Avoid soybean-based foods, which decrease absorption. 2

Monitoring Protocol

Recheck TSH and free T4 in 6-8 weeks after restarting therapy, as this represents the time needed to reach steady-state levothyroxine concentrations. 1, 3, 2 The peak therapeutic effect may not be attained for 4-6 weeks. 2

• Target TSH: 0.5-4.5 mIU/L with normal free T4 for primary hypothyroidism. 1, 3

• Dose adjustments: Increase by 12.5-25 mcg increments every 6-8 weeks until TSH normalizes. 1, 3, 2

• Once stable: Monitor TSH every 6-12 months or sooner if symptoms change. 1, 3

Special Considerations for This Clinical Scenario

The presence of goiter and symptomatic hypothyroidism with TSH >10 mIU/L (yours is 211,000) mandates immediate treatment regardless of age or symptoms, as this level carries severe cardiovascular risk including heart failure, delayed myocardial relaxation, abnormal cardiac output, and increased systemic vascular resistance. 1, 5, 6

Untreated severe hypothyroidism can progress to myxedema coma (mortality 30%), characterized by hypothermia, hypotension, and altered mental status requiring ICU care. 5 The patient's current symptomatic state with goiter suggests they are at risk for this complication if treatment is further delayed.

Common Pitfalls to Avoid

• Never delay treatment to "start low and go slow" in young patients without cardiac disease—the previous dose of 137 mcg is their known requirement and months of severe deficiency demand full replacement. 1, 2

• Never restart thyroid hormone before ruling out adrenal insufficiency in patients with suspected central hypothyroidism or autoimmune polyglandular syndrome, as this can trigger adrenal crisis. 1, 3

• Do not adjust doses more frequently than every 6-8 weeks, as levothyroxine has a long half-life and premature adjustments lead to inappropriate dosing. 1, 3, 2

• Approximately 25% of patients on levothyroxine are unintentionally overtreated with suppressed TSH, increasing risks for atrial fibrillation (3-5 fold), osteoporosis, fractures, and cardiovascular mortality—monitor carefully to avoid this. 1, 6

Addressing Non-Adherence

Before restarting, identify and address barriers to adherence: medication cost, side effects, misunderstanding of lifelong need, difficulty with timing requirements, or depression from untreated hypothyroidism itself. 5, 7 Emphasize that levothyroxine is lifelong replacement therapy for a deficient hormone, not optional medication, and that stopping causes the current severe symptoms plus life-threatening complications. 5, 7

Expected Clinical Response

Symptomatic improvement (fatigue, weight, cold intolerance, cognitive function) should begin within 6-8 weeks of adequate replacement, with full resolution by 3-4 months. 1, 5, 7 The goiter may decrease in size over several months as TSH normalizes. 1