75mcg Levothyroxine starter dose?

[RuthNelson]

Hi,

75mcg is what I've been prescribed by the endo. I last took Levothyroxine many years ago for recurrent miscarriage.

Have just read the leaflet in the pill packet which says that those over 50 years old should start on 50mcg; I am 53, should I be worried?

Thanks!

[helvella Administrator]

A very difficult question.

It used to be pretty much universal that adults started on 50 micrograms (or 25 in some cases), then dose gets incremented.

Somewhere about twenty years ago, there were some trials (I remember in in Netherlands) of starting on 100. The results were, in my view, somewhat equivocal.

However, the NICE guidelines now say:

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.

1.3.7

Consider starting levothyroxine at a dosage of 25 to 50 micrograms per day with titration for adults aged 65 and over and adults with a history of cardiovascular disease.

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

My view is that dosing by weight is a bad idea.

helvella's calculation document and spreadsheet can be can be found by following this link:

helvella - Estimation of Levothyroxine Dosing in Adults

A discussion about the use of formulas to estimate levothyroxine dosing. Includes link to a downloadable spreadsheet which calculates several of these.

helvella.blogspot.com/p/hel...

At the same time, some people need their initial dose to be raised quite quickly. Waiting months to receive an increment from, say, 50 to 75 (or 50 to 62.5) is dreadful management. Especially when it is very obvious that a dose increase is required.

I end up thinking that 50 to 75 is possibly reasonable, but first increase(s) should be prepared for and expected.

[RuthNelson in reply to helvella]

Brilliantly comprehensive, thank you! I take from this that I should not be worried about going straight to 75.

[helvella Administrator in reply to RuthNelson]

I would not be worried but your journey from first dose might be a bit different to those who start on, say 25 or 50.

However, if your prescription is written for 75, then there are only two possible products. Teva and Crescent.

Teva splits opinions between being excellent and causing problems. Crescent has literally only become available in the last few days. Hence there is next to no reported experience. I don't think there is any way to be sure (unless you specifically cannot tolerate one of the excipients) ahead of trying them.

Hope it goes well for you.

[RuthNelson]

thank you; I have been given Crescent.

[McPammy]

Or you could request liquid levothyroxine which you can dispense in any quantity dose. Liquid also absorbs much better than tablets. Liquid is so easy to use and you can tailor your dose exactly to suit yourself. It’s a bit more expensive so you’ll have to make a request via your medication manager at your surgery or directly with then endocrinologist.

[RuthNelson]

thank you; I have been given 3 months worth of Crescent, so will see how I get on with them, but good to know that there are other options!