What are the next steps for a patient with elevated Thyroid-Stimulating Hormone (TSH) levels, indicating potential hypothyroidism?

Management of Elevated TSH

Confirm the elevated TSH with repeat testing after 3-6 weeks along with free T4 measurement, as 30-60% of elevated TSH levels normalize spontaneously 1.

Initial Confirmation and Assessment

Before making any treatment decisions, you must verify the TSH elevation is persistent and not transient 1:

• Repeat TSH and measure free T4 after 3-6 weeks (minimum 2 weeks, maximum 3 months) to distinguish between subclinical hypothyroidism (normal free T4) and overt hypothyroidism (low free T4) 1, 2
• Check anti-TPO antibodies to identify autoimmune etiology, which predicts higher progression risk (4.3% per year vs 2.6% in antibody-negative individuals) 1
• Review recent history for transient causes: acute illness, recent iodine exposure (CT contrast), recovery from thyroiditis, or medications that affect thyroid function 1

Treatment Algorithm Based on Confirmed TSH Levels

TSH >10 mIU/L: Treat Regardless of Symptoms

Initiate levothyroxine therapy immediately for all patients with confirmed TSH >10 mIU/L, as this carries approximately 5% annual risk of progression to overt hypothyroidism and is associated with cardiovascular dysfunction 1:

• For patients <70 years without cardiac disease: Start levothyroxine at full replacement dose of 1.6 mcg/kg/day 1, 3
• For patients >70 years or with cardiac disease: Start at 25-50 mcg/day and titrate gradually to avoid unmasking cardiac ischemia or precipitating arrhythmias 1, 3
• For pregnant women or those planning pregnancy: Start 1.6 mcg/kg/day immediately, as untreated hypothyroidism increases risk of preeclampsia, low birth weight, and neurodevelopmental effects 1

TSH 4.5-10 mIU/L: Individualized Approach

For TSH between 4.5-10 mIU/L, routine levothyroxine treatment is NOT recommended; instead, monitor thyroid function every 6-12 months 1:

Consider treatment in specific situations 1:

• Symptomatic patients with fatigue, weight gain, cold intolerance, or constipation—offer a 3-4 month trial with clear evaluation of benefit 1
• Positive anti-TPO antibodies (4.3% annual progression risk) 1
• Women planning pregnancy (target TSH <2.5 mIU/L before conception) 1
• Patients already on levothyroxine with inadequate dosing 1

Critical Safety Consideration: Rule Out Adrenal Insufficiency

Before initiating or increasing levothyroxine, always rule out concurrent adrenal insufficiency, especially in suspected central hypothyroidism, as starting thyroid hormone before corticosteroids can precipitate life-threatening adrenal crisis 1, 2:

• Check morning cortisol and ACTH if central hypothyroidism suspected (low or inappropriately normal TSH with low free T4) 2
• Start physiologic dose steroids 1 week prior to thyroid hormone replacement if adrenal insufficiency confirmed 1, 2

Monitoring and Dose Adjustment

Recheck TSH and free T4 every 6-8 weeks after initiating therapy or any dose change, as this represents the time needed to reach steady state 1, 3:

• Target TSH: 0.5-4.5 mIU/L for primary hypothyroidism 1, 3
• Dose adjustments: Increase by 12.5-25 mcg increments based on patient age and cardiac status 1
• Once stable: Monitor TSH annually or sooner if symptoms change 1, 3

Common Pitfalls to Avoid

• Never treat based on single elevated TSH value—30-60% normalize on repeat testing 1
• Never start thyroid hormone before ruling out adrenal insufficiency in suspected central hypothyroidism 1, 2
• Avoid overtreatment—14-21% of treated patients develop iatrogenic hyperthyroidism, increasing risk for atrial fibrillation (especially in elderly), osteoporosis, and fractures 1
• Don't adjust doses too frequently—wait full 6-8 weeks between adjustments to reach steady state 1
• Don't miss transient hypothyroidism—recovery phase from thyroiditis can cause temporary TSH elevation 1

Special Populations

Elderly patients (>70 years) 1:

• Start at lower dose (25-50 mcg/day) to avoid cardiac complications
• Use smaller dose increments (12.5 mcg)
• Consider slightly higher TSH targets acceptable to avoid overtreatment risks

Pregnant women 1, 3:

• Treat any TSH elevation immediately
• Target TSH <2.5 mIU/L in first trimester
• Increase pre-pregnancy dose by 25-50% upon pregnancy confirmation
• Monitor TSH every 4 weeks until stable, then each trimester

Patients with cardiac disease 1:

• Start at 25-50 mcg/day maximum
• Titrate slowly with 12.5 mcg increments
• Obtain baseline ECG to screen for arrhythmias
• Monitor closely for angina, palpitations, or worsening heart failure