What to do next for a 70-year-old patient with elevated TSH (Thyroid-Stimulating Hormone) and low FT4 (Free Thyroxine)?

Management of Overt Hypothyroidism in a 70-Year-Old Patient

Initiate levothyroxine therapy immediately at a starting dose of 25-50 mcg daily, as this patient has overt hypothyroidism (elevated TSH 8.331 mIU/L with low FT4 0.85) requiring treatment regardless of symptoms. 1

Diagnostic Confirmation and Assessment

• This patient has overt hypothyroidism, not subclinical hypothyroidism, because both TSH is elevated (8.331 mIU/L) AND FT4 is low (0.85), distinguishing it from subclinical disease where FT4 would be normal 1, 2
• Before initiating treatment, confirm the diagnosis is not transient by checking for recent iodine exposure (CT contrast), acute illness, or medication changes that could transiently affect thyroid function 1
• Measure thyroid peroxidase (TPO) antibodies to identify autoimmune etiology, which predicts higher progression risk and supports long-term treatment 1, 3
• Critical: Rule out concurrent adrenal insufficiency before starting levothyroxine, as initiating thyroid hormone in a patient with undiagnosed adrenal insufficiency can precipitate adrenal crisis 4, 1

Initial Treatment Protocol for Elderly Patients

For patients over 70 years old, start with a conservative dose of 25-50 mcg daily rather than full replacement dosing, to minimize cardiac risks 1, 5:

• The full replacement dose calculation of 1.6 mcg/kg/day is NOT appropriate for elderly patients or those with cardiac disease 1
• Start at 25-50 mcg daily and titrate gradually by 12.5-25 mcg increments every 6-8 weeks based on TSH response 1, 5
• This conservative approach is essential because elderly patients have higher risk of cardiac complications including angina, arrhythmias, and atrial fibrillation with overly aggressive treatment 1, 5

Monitoring and Dose Titration

• Recheck TSH and free T4 in 6-8 weeks after starting therapy to assess response 1, 5
• Continue dose adjustments every 6-8 weeks until TSH normalizes to the target range of 0.4-2.5 mIU/L (lower half of reference range) 1, 3
• For elderly patients specifically, age-adjusted TSH targets may be appropriate, with upper limit of normal around 7.5 mIU/L for patients over 80 years 3, 6
• Once stable, monitor TSH annually or sooner if symptoms change 1, 5

Special Considerations for This 70-Year-Old Patient

• Screen for cardiac disease (history of angina, heart failure, arrhythmias) before initiating treatment, as presence of cardiac disease mandates even more cautious dosing 1, 5
• If cardiac disease is present, consider starting at 25 mcg daily (lower end of range) and increase by only 12.5 mcg increments 1
• Educate the patient that symptom improvement may take several weeks, and replacement therapy is typically lifelong 5
• Ensure proper administration: take on empty stomach, 30-60 minutes before breakfast with full glass of water 5
• Avoid taking within 4 hours of calcium, iron supplements, or antacids which impair absorption 5

Critical Pitfalls to Avoid

• Never start with full replacement dosing (1.6 mcg/kg/day) in elderly patients, as this significantly increases risk of cardiac complications including atrial fibrillation and myocardial ischemia 1, 5
• Do not delay treatment waiting for repeat testing in overt hypothyroidism (unlike subclinical hypothyroidism where confirmation is needed), as both TSH and FT4 are clearly abnormal 1, 2
• Avoid overtreatment, which occurs in 25% of patients on levothyroxine and increases risk for osteoporosis, fractures, and cardiac arrhythmias 4, 1
• Do not use TSH alone for monitoring during dose titration—measure both TSH and free T4, as free T4 helps interpret ongoing abnormal TSH levels 1
• Never initiate thyroid hormone if adrenal insufficiency is suspected without first starting corticosteroids, as this can precipitate life-threatening adrenal crisis 4, 1

Long-Term Management

• Once TSH is stable in target range (0.4-2.5 mIU/L), monitor annually with TSH and free T4 1, 3
• Reassess if new symptoms develop, new medications are started, or significant weight change occurs 1
• Levothyroxine requirements may change with aging, illness, or other medications, necessitating periodic dose adjustments 5
• Educate patient on signs of overtreatment (palpitations, tremor, weight loss, heat intolerance) and undertreatment (fatigue, weight gain, cold intolerance) 5