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HealthRX.com · Printable lab tracker

Levothyroxine with NMN or NR: morning routine and TSH tracker

Log your first two weeks of morning timing, then keep your TSH and free T4 results on one sheet with the levothyroxine and NAD+ precursor doses you were taking at the time. The label facts beside them explain which timings and supplements actually change absorption or test results.

Companion to “NMN/NR and Levothyroxine Interaction: Safety, Timing, and What the Evidence Says” · healthrx.com/interactions-nad-nmn/with-levothyroxine · Facts checked 2026-10-18

Your thyroid treatment

Levothyroxine brand and strength (mcg)
Time you take itmorning before breakfast, or bedtime
Why you take ithypothyroidism, or TSH suppression after thyroid cancer
TSH range your clinician is aiming for
Pregnant or planning a pregnancy?

Your NAD+ precursor

NMN or NR product and amount per day
Time of day you take it
Date started, or date stopped
Other ingredients on its labellook for calcium, iron or biotin

Morning timing, first two weeks

Write clock times. The point is a routine you can repeat every day, not a perfect one.

DayLevothyroxineBreakfastNMN or NRCalcium, iron or antacidNotes

TSH and free T4 results

Ask the lab for the reference ranges, and note whether you stopped biotin first.

WhenDateTSHFree T4Levothyroxine doseNMN or NR doseBiotin stopped 2+ days before?
Baseline, before NMN or NR
6 to 8 weeks after starting
After any change in either
Yearly, if stable

What the Synthroid label says

  • Only 40% to 80% of an oral levothyroxine (T4) dose is absorbed, which is why timing and what you swallow with it matter.[1]
  • Take it once a day on an empty stomach, one-half to one hour before breakfast.[1]
  • Keep calcium carbonate, ferrous sulfate and other phosphate binders at least 4 hours away from the dose.[1]
  • Antacids, sucralfate and proton pump inhibitors can lower stomach acid and reduce levothyroxine absorption.[1]
  • Slow-release nicotinic acid (a niacin product, not NMN or NR) is listed among drugs that may lower thyroid-binding protein (TBG), in the label's table of drugs that change thyroid hormone transport in the blood without affecting free T4.[1]
  • Stop biotin and biotin-containing supplements at least 2 days before thyroid blood tests.[1]
  • T4 has a half-life of 6 to 7 days in people with normal thyroid levels and 9 to 10 days in hypothyroidism.[1]
  • In pregnancy, TSH and free T4 are checked as soon as pregnancy is confirmed and at least once each trimester.[1]

Questions for your endocrinologist

  1. What TSH range are we aiming for in my case?
  2. Given when I take levothyroxine, when in the day should NMN or NR go?
  3. If my TSH moves after I start NMN or NR, should we check timing and adherence before changing my dose?
  4. I am on TSH suppression after thyroid cancer: should my recheck come sooner than 6 to 8 weeks?
  5. My NAD+ product lists other ingredients. Do any of them change the timing?
Sources for the facts on this sheet
  1. AbbVie Inc., via DailyMed. Synthroid (levothyroxine sodium) tablets, for oral use: prescribing information. Effective 2024-02-20. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1e11ad30-1041-4520-10b0-8f9d30d30fcc

This sheet records information for a conversation with your prescriber or pharmacist. It does not replace their instructions or the medication's prescribing information.