When can I expect my resting heart rate to increase on Levo?

[ockerdoc]

I’m on 87.5mcg Levo now but my resting heart rate is still late 40s and I’m not an athlete by any stretch of the imagination. Will it go up when I’m properly medicated? Just curious really as I’ve been expecting it to gradually go up but it hasn’t moved. Thank you.

[seveneleven]

Likely won't until you're on a higher dose, but then also will depend if you're actually converting to T3. My HR has only started picking up (from 40s-50s) since adding T3 because I wasn't able to utilise the T4 alone. So you'll need to look at bloods once you've been on your current dose 6-8 weeks to see where you're at. Have you felt any improvement in anything since starting levo? How long have you been on it?

[ockerdoc in reply to seveneleven]

Thanks for the reply yes I’ve felt some improvement but think I need to be on a higher dose. Still feeling tired after exercise but improved in brain fog and overall zest for life coming back. My conversion is ok and my T3 was 52% through range at last test. I’m also 6.2 and 14.5 stone. Will be testing in around 2 weeks and hopefully move up to 100mcg. I was just expecting it to go up as I increased the Levo. I’ll just wait n see when I’ve upped my dose thank you.

[SlowDragon Administrator in reply to ockerdoc]

14 stone 5lbs = 91kg

91kg x 1.6mcg = 145mcg as likely eventual daily dose levothyroxine required

So you’re still some way off final dose

Some people don’t need quite as much as guidelines, some need slightly higher dose

Essential to maintain GOOD vitamin levels to help reduce symptoms and tolerate increasing levothyroxine dose

Even if we frequently start on only 50mcg, most people need to increase levothyroxine dose slowly upwards in 25mcg steps (retesting 6-8 weeks after each increase) until eventually on, or near full replacement dose

NICE guidelines on full replacement dose

nice.org.uk/guidance/ng145/...

1.3.6

Consider starting levothyroxine at a dosage of 1.6 micrograms per kilogram of body weight per day (rounded to the nearest 25 micrograms) for adults under 65 with primary hypothyroidism and no history of cardiovascular disease.

Also here

cks.nice.org.uk/topics/hypo...

pathlabs.rlbuht.nhs.uk/tft_...

Guiding Treatment with Thyroxine:

In the majority of patients 50-100 μg thyroxine can be used as the starting dose. Alterations in dose are achieved by using 25-50 μg increments and adequacy of the new dose can be confirmed by repeat measurement of TSH after 2-3 months.

The majority of patients will be clinically euthyroid with a ‘normal’ TSH and having thyroxine replacement in the range 75-150 μg/day (1.6ug/Kg on average).

The recommended approach is to titrate thyroxine therapy against the TSH concentration whilst assessing clinical well-being. The target is a serum TSH within the reference range.

……The primary target of thyroxine replacement therapy is to make the patient feel well and to achieve a serum TSH that is within the reference range. The corresponding FT4 will be within or slightly above its reference range.

The minimum period to achieve stable concentrations after a change in dose of thyroxine is two months and thyroid function tests should not normally be requested before this period has elapsed.

[ockerdoc in reply to SlowDragon]

Thank you it’s good to know I’ve still got room to increase 👍

[crimple]

ockerdoc, my resting HR only rose over 60 from 56 once I had some T3

[ockerdoc in reply to crimple]

Thank you 🙏