Medication
Biotin and Thyroid Labs: Why Your Supplement May Be Skewing Your Results
High-dose biotin supplements cause falsely low TSH and falsely high T3/T4 on standard lab tests. The FDA warned about this in 2017. Here's what to do.
Calcium, Iron, and Levothyroxine: The 4-Hour Rule
Calcium and iron levothyroxine interactions can cut absorption by 25-30% and push TSH from 1.6 to 5.4. Why the 4-hour rule matters and how to apply it.
Coffee and Levothyroxine Timing: The 60-Minute Window
Coffee levothyroxine timing matters more than most patients are told. Benvenga 2008 found about 36% less T4 absorption when taken together. Wait 60 min.
Fiber Supplements and Levothyroxine: The 4-Hour Rule That Protects Your Dose
Dietary fiber and fiber supplements like psyllium can bind levothyroxine in the gut and reduce absorption. Learn the simple timing rule that prevents this.
Generic vs Brand Levothyroxine: Does It Matter?
Generic vs brand levothyroxine: neither is inherently better. The FDA calls it a narrow-therapeutic-index drug, so consistency and TSH retesting matter most.
Levothyroxine on an Empty Stomach: Why Timing Matters
Levothyroxine empty stomach: why it matters. Acidic, food-free conditions let the tablet dissolve and reach the small intestine for 70-80% absorption.
Proton Pump Inhibitors and Levothyroxine: Why Your Heartburn Drug May Be Raising Your TSH
PPIs like omeprazole and pantoprazole raise stomach pH and impair levothyroxine absorption. Learn how to manage this clinically important drug interaction.
T3/T4 Combination Therapy: Is Adding Liothyronine Right for You?
Still feeling unwell on levothyroxine with a normal TSH? Learn what the research says about adding T3 (liothyronine) and who may actually benefit.