What patient counseling is required when initiating levothyroxine (thyroid hormone replacement therapy) in patients with hypothyroidism, including those with a history of heart disease?

Patient Counseling for Levothyroxine Initiation

Timing and Administration

Take levothyroxine as a single dose on an empty stomach, 30-60 minutes before breakfast with a full glass of water to prevent choking and optimize absorption. 1

• Taking levothyroxine with breakfast instead of fasting increases TSH levels by approximately 1.47 µIU/mL and reduces therapeutic efficacy 2, 3
• Only 39% of patients follow the recommended timing of taking levothyroxine ≥30 minutes before eating, which contributes to suboptimal thyroid control 4
• If morning administration is difficult, taking levothyroxine before dinner (1 hour before the meal) is an alternative, though it results in slightly higher TSH levels and requires closer monitoring 2

Drug and Food Interactions

Do not take levothyroxine within 4 hours of iron supplements, calcium supplements, or antacids, as these agents significantly decrease absorption. 1

• Approximately 7% of patients concurrently use molecules that bind to levothyroxine without applying the recommended dosing interval, compromising treatment effectiveness 4

Timeline for Symptom Improvement

It may take several weeks (typically 6-8 weeks) before you notice improvement in symptoms such as fatigue, weight changes, or cognitive difficulties. 1, 5

• Hypothyroidism commonly causes fatigue (68-83% of patients), weight gain (24-59%), cognitive issues (45-48%), and menstrual irregularities (23%) 5
• Partial hair loss may occur rarely during the first few months of therapy, but this is usually temporary 1

Lifelong Therapy Requirement

Levothyroxine is intended to replace a hormone normally produced by your thyroid gland, and replacement therapy is generally taken for life. 1

• Levothyroxine should not be used as a primary or adjunctive therapy in a weight control program 1

Monitoring Requirements

Your healthcare provider will check your TSH levels 6-8 weeks after starting levothyroxine or changing the dose, then annually once levels are stable. 6, 5

• Approximately 25% of patients are unintentionally maintained on doses that fully suppress TSH, increasing risks for atrial fibrillation, osteoporosis, and cardiac complications 7

Special Precautions for Cardiac Patients

If you have heart disease, your starting dose will be lower (25-50 mcg/day) and increased gradually to avoid unmasking cardiac ischemia or precipitating arrhythmias. 7, 6

• Rapid normalization of thyroid hormone can worsen cardiac ischemia in patients with coronary artery disease 7
• Notify your physician immediately if you experience rapid or irregular heartbeat, chest pain, or shortness of breath 1

Other Medical Conditions Requiring Dose Adjustments

Notify your physician if you have diabetes, clotting disorders, or adrenal/pituitary gland problems, as medications for these conditions may need adjustment. 1

• If you have diabetes, monitor blood glucose levels as directed, as hypothyroidism can cause insulin resistance and hyperglycemia 1, 5
• If taking anticoagulants, clotting status should be checked frequently 1

Pregnancy and Breastfeeding

Notify your healthcare provider immediately if you are pregnant, breastfeeding, or planning to become pregnant, as levothyroxine requirements typically increase by 25-50% during pregnancy. 1, 7

• Untreated hypothyroidism during pregnancy increases risk of preeclampsia, low birth weight, miscarriage, and neurodevelopmental effects in offspring 7

Warning Signs Requiring Immediate Medical Attention

Contact your healthcare provider if you experience any of the following symptoms of overtreatment or undertreatment: 1

• Rapid or irregular heartbeat, chest pain, shortness of breath
• Leg cramps, headache, nervousness, irritability, sleeplessness, tremors
• Significant changes in appetite, weight gain or loss, vomiting, diarrhea
• Excessive sweating, heat intolerance, fever
• Changes in menstrual periods, hives, skin rash, or any unusual medical event

Adherence Importance

Take levothyroxine exactly as prescribed—approximately 28% of patients miss at least 73 cumulative days per year, which compromises thyroid control. 4

• Unintentional non-adherence due to forgetfulness is the most common reason for missed doses (21.9% of patients) 4
• Setting a daily alarm or using a pill organizer can help maintain consistent dosing

Surgery Notification

Notify your physician or dentist that you are taking levothyroxine prior to any surgery. 1