Is it dangerous to start on 100mcg of Levo?

[buddy99]

I am not sure how to answer this question put to me by a person with a TSH of 23. Personally I think it is a shock to the system to start off that high. There are so many knowledgeable people here, I thought I pass the question on. The TSH is the only info I have but I assume that the T4 for this person is not high. Thanks for any input I can get.

[Lalatoot]

Buddy. You would need to know the age of the person and any underlying health conditions.The guidelines are start at 25mcg for elderly and those with heart conditions. Otherwise normally 50mcg.

Folks can start on an elevated dose in exceptional circumstances if it is considered right for them. With only TSH and no other info plus the fact that we are not medically trained, I don't think we can advise.

[buddy99 in reply to Lalatoot]

Thank you, Lalatoot, for your thoughts. My thinking was along the same lines. The person is 70 years old. The age was my main concern. I did not want to advise either but hope the doc doesn't screw this up. 😬

[SlowDragon Administrator]

Modern guidelines are to start on higher dose, but if been hypothyroid a long time before starting it can be too much to tolerate. Therefore most patients still start on 50mcg, and increase slowly upwards over several months

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...

gp-update.co.uk/files/docs/...

Traditionally we have tended to start patients on a low dose of levothyroxine and titrate it up over a period of months. RCT evidence suggests that for the majority of patients this is not necessary and may waste resources.

For patients aged >60y or with ischaemic heart disease, start levothyroxine at 25–50μg daily and titrate up every 3 to 6 weeks as tolerated.

For ALL other patients start at full replacement dose. For most this will equate to 1.6 μg/kg/day (approximately 100μg for a 60kg woman and 125μg for a 75kg man).

If you are starting treatment for subclinical hypothyroidism, this article advises starting at a dose close to the full treatment dose on the basis that it is difficult to assess symptom response unless a therapeutic dose has been trialled.

BMJ also clear on dose required

bmj.com/content/368/bmj.m41

[buddy99 in reply to SlowDragon]

Thanks, Slow Dragon, for the, as always, precise info.

[helvella Administrator]

Some time ago, probably about fifteen years, there was a paper from a team in Netherlands who trialled putting people onto a higher dose, pretty much the full replacement dose, immediately after diagnosis. Since then, it has changed from being trialled to policy in some places and circumstances.

They claimed that the results were pretty similar to the control group who were started on the more conventional lower dose and then incremented.

I fundamentally disagree. If someone is, like me, not going to need as much as the calculated dose, they would be started on a higher dose than they ever need. That would be unacceptable, in my view.

Also, starting people on such a high dose who might have been hypothyroid for years is asking a lot of their bodies.

My interpretation would be at most somewhere around 75% of expected dose. Making due allowance for how long they have been hypothyroid.

(At the other end of the scale, starting someone who is profoundly hypothyroid on 25 micrograms likely means they will, within days, find themselves running out well before their next dose is due. So ramping up needs to be faster. But that is another story.)

[tattybogle]

When i started i was age 30 ish , and 'otherwise' very fit , even though i had been increasingly hypo for a few years and felt dreadfully exhausted and cold all the time. But my TSH was only 6.8 I did 50 straight off and increased to 100mcg after 7 weeks and later 150, with no problem whatsoever.

So personally i think i would have been fine if they gave me 100mcg to start on.

But what if my right dose had been 87.5mcg ... which it might have been , they don't really know do they ? , and my TSH at the time was no use whatsoever as a guide for the correct dose .. it sat stubbornly at 2.5 ish on 50 and 100 and 150 . for over a year before falling lower.

So i agree with Helvella , for a lot of people you probably could start them at 75mcg without it being any problem .. and 25mcg does just seem to be prolonging the agony in many cases.

But i wouldn't fancy giving 100mcg to somebody who was 70 and with a 'high' TSH .

I think the general principle is that if the body is very hypo, and especially if it has been for a while and all the systems have got used to functioning at a much slower rate, then giving it so much in one go might be rather a big shock for it.

Even for an 'otherwise' healthy 70 yr old, with TSH 23 ,, the fastest i'd want to go would be to start at 50 for a month and then assuming no issues ,do 75 ,and then wait a full 8 weeks to see what to do next .

[SlowDragon Administrator in reply to tattybogle]

The problem with starting on 75mcg levothyroxine…..they would almost certainly get Teva brand levothyroxine as it’s only brand that makes 75mcg tablets

[tattybogle in reply to SlowDragon]

oh yes ..hadn't thought of that... it makes me feel so naff , i hate to think what would have happened if that had been my first introduction to taking levo. Fortunately i'd been used to a few other brands with no major issue for many yrs before a new chemist gave me Teva .. so i knew something felt a bit 'off' ., even though it still took while for me to realise what it was .

It's a shame none of the other manufacturers make such a good range of doses as Teva do ... i think they should all be 'encouraged' to make 12.5 /25/ 50 /100 if they are going to make any at all.

[helvella Administrator]

This is the Netherlands paper I referred to earlier:

Paper which compared patients started on a calculated full replacement dose of levothyroxine against starting at 25 micrograms and incrementing every four weeks.

Original Investigation

August 8/22, 2005

The Starting Dose of Levothyroxine in Primary Hypothyroidism TreatmentA Prospective, Randomized, Double-blind Trial

Annemieke Roos, MD; Suzanne P. Linn-Rasker, MD; Ron T. van Domburg, PhD; et alJan P. Tijssen, PhD; Arie Berghout, MD, PhD, FRCP

Author Affiliations Article Information

Author Affiliations: Department of Internal Medicine, Medical Centre Rijnmond-Zuid, Rotterdam (Drs Roos, Linn-Rasker, and Berghout), Department of Cardiology, Erasmus Medical Centre, Rotterdam (Dr van Domburg), and Department of Cardiology, Academic Medical Centre, Amsterdam (Dr Tijssen), the Netherlands.

Arch Intern Med. 2005;165(15):1714-1720. doi:10.1001/archinte.165.15.1714

Abstract

Background The treatment of hypothyroidism with levothyroxine is effective and simple; however, recommendations for the starting dose vary considerably. To our knowledge, the levothyroxine starting dose has never been studied prospectively.

Methods We conducted a prospective, randomized, double-blind trial that compared a full starting levothyroxine dose of 1.6 μg/kg with a low starting dose of 25 μg (increased every 4 weeks) in patients with newly diagnosed cardiac asymptomatic hypothyroidism. Safety was studied by documenting cardiac symptoms and events, and efficacy was studied by monitoring thyrotropin and free thyroxine levels and by assessing improvement of signs and symptoms and quality of life.

Results Seventy-five consecutive patients were enrolled, of whom 50 underwent randomization. At baseline, the severity of hypothyroidism and age were comparable in the full-dose (n = 25) vs the low-dose group (n = 25): thyrotropin, 61 vs 48 mIU/L; free thyroxine, 0.56 vs 0.64 ng/dL (7.2 vs 8.2 pmol/L); and age, 47 vs 47 years. No cardiac complaints or events were documented during treatment or at bicycle ergometry at baseline, 12 weeks, or 24 weeks. Euthyroidism was reached in the full-dose vs the low-dose group in 13 vs 1 (4 weeks), 19 vs 3 (8 weeks), 19 vs 9 (12 weeks), 20 vs 14 (16 weeks), 20 vs 18 (20 weeks), and 21 vs 20 (24 weeks) patients (P = .005). However, signs and symptoms of hypothyroidism and quality of life improved at a comparable rate.

Conclusion A full starting dose of levothyroxine in cardiac asymptomatic patients with primary hypothyroidism is safe and may be more convenient and cost-effective than a low starting dose regimen.

Primary hypothyroidism is a common disorder, most prevalent in women and most often caused by autoimmune thyroiditis. Overt hypothyroidism can present with classic symptoms of fatigue, weight gain, cold intolerance, and constipation. Fatigue, one of the major complaints, together with depression,1 neuromuscular signs and symptoms,2 and diastolic dysfunction3 can all lead to an impaired quality of life in patients with hypothyroidism. Furthermore, abnormalities of lipid metabolism, hyperhomocysteinemia, and arterial hypertension occur with increased frequency in hypothyroidism4,5 and are associated with an increased risk of premature atherosclerotic vascular disease.6,7

Although the treatment of hypothyroidism with levothyroxine, one of the most commonly prescribed drugs, seems effective and simple, recommendations for the starting dose of levothyroxine vary considerably: from 50 μg to a full replacement dose of 1.6 or 1.7 μg/kg in healthy adult patients younger than 65 years and from 25 to 50 μg/d in older patients and patients with known ischemic heart disease.8-13 The safety and efficacy of different initial doses of levothyroxine have, to our knowledge, never been studied prospectively. Moreover, in daily practice, many physicians still promote the dogma of “start low and go slow” irrespective of age or patient. This dogma is based on the association of hypothyroidism with ischemic heart disease.14,15 Interestingly, and in contradiction to this dogma, high doses of levothyroxine have been given to patients with myxedema coma, a patient group in whom a high prevalence of cardiac ischemia would be expected, without untoward effects.16 However, when levothyroxine was combined with triiodothyronine (T3) in the treatment of such severely ill patients, fatal outcome has been reported.9 Several case series and retrospective studies, dating back 4 to 6 decades, have shown considerable variability in the cardiac responses of patients with hypothyroidism to thyroid hormone therapy, ranging from precipitating acute coronary syndromes in patients without previous cardiac symptoms14,17 to controlling or even abolishing preexisting angina.17,18 These studies can be criticized for being retrospective, cross-sectional, or uncontrolled; for having small numbers of patients; or for using desiccated thyroid preparations that contain differing and therefore unpredictable amounts of both levothyroxine and T3. Levothyroxine is converted into T3 by type 1 deiodinase in the liver.19 The evidence for local deiodination of total thyroxine (T4) in the human heart by type 2 deiodinase20,21 and the increased expression of type 2 deiodinase in the mouse heart during hypothyroidism22 could indicate mechanisms of adaptation in case of low or high serum levels of T4.

Most reviews report a period of 4 to 6 months before normalization of plasma thyrotropin and free thyroxine (FT4) levels is attained.8-12 A more rapid normalization could be of great benefit to patients with hypothyroidism regarding the reduction of cardiac risk factors, improvement of quality of life, and being less cumbersome for regular visits to the clinics. However, the efficacy and safety of different initial doses of levothyroxine have surprisingly never been studied prospectively in patients with primary hypothyroidism. This prompted us to compare a full initiating treatment dose of levothyroxine (1.6 μg/kg)23 with the classic approach of “start low and go slow” in a prospective, randomized, double-blind study. The aim of the study was to prove that restoration of plasma thyrotropin and FT4 levels within the normal reference range can be performed with a straightforward high-dose regimen without any increased risk of major adverse cardiac events.

jamanetwork.com/journals/ja...

I think we need to realise that the best approach might well be one which tested every single day. (Possibly even more often very early. To catch the situations in which the thyroid hormone seems to run out well before the next dose.) That would allow blood levels and clinical assessment to go together and raise dose fairly fast, but not too fast for the individual. Of course, the cost of so doing is prohibitive.

But that is behind my hope that some technological development would allow indirect assessment of thyroid status - if not actual measurement of thyroid hormones.

[tattybogle in reply to helvella]

"... that is behind my hope that some technological development would allow indirect assessment of thyroid status - if not actual measurement of thyroid hormones."

If they could come up with a thing that does that , even 'yours truly' might be prepared to buy one and figure out how to use 'an app' .

[SlowDragon Administrator in reply to helvella]

We need one like diabetics have on their arm ….continuous glucose monitor…..instantly reads blood sugar on your phone

verywellhealth.com/freestyl...

[helvella Administrator in reply to SlowDragon]

I used to think that. But given that even major pathology laboratories seem to be inconsistent with each other, I suspect that a combination of factors such as core temperature, heart (possibly needing sophisticated analysis of an ECG), conductivity, muscle responses, etc., might be a better approach. Both because it is likely more achievable at a sensible price and in a sensible time.

[SlowDragon Administrator in reply to helvella]

Well a fitness watch is a good compromise

I find giving GP graphs of daily resting heart rate and “lowest heart rate at night” helps significantly with medics NOT reducing dose

[radd]

buddy99,

It is dependant upon many factors such as age, how compromised the body has become if diagnosis has taken many years, reason for hypothyroidism, ie autoimmune disease, thyroidectomy, etc

I was left undiagnosed for years & years, and then diagnosed with a TSH of 45, started on 100mcg Levo and immediately became further unwell with heart issues, breathlessness, vertigo, etc. There is little doubt I should have had Levo introduced slowly with adrenal support to have gained a better tolerance.

[buddy99 in reply to radd]

Thanks for your input, radd. She is 70 years old and has autoimmune thyroiditis and another autoimmune disease. Who knows how long she's been hypo. I start to think that the safer way might be to start her on 50mcg. Maybe, for once, a doctor is worried about myxedema. Usually they are worried silly about thyrotoxicosis.

[radd in reply to buddy99]

Yes, NICE states Levo should be introduced slowly in the elderly to avoid increase in metabolic demand. I hope it works for them and they feel better soon 😊.

[buddy99 in reply to radd]

Thanks. I hope so too.

[SlowDragon Administrator in reply to buddy99]

If she’s over 60 years old standard starter dose levothyroxine is 25mcg

gp-update.co.uk/files/docs/...

Traditionally we have tended to start patients on a low dose of levothyroxine and titrate it up over a period of months. RCT evidence suggests that for the majority of patients this is not necessary and may waste resources.

For patients aged >60y or with ischaemic heart disease, start levothyroxine at 25–50μg daily and titrate up every 3 to 6 weeks as tolerated.

For ALL other patients start at full replacement dose. For most this will equate to 1.6 μg/kg/day (approximately 100μg for a 60kg woman and 125μg for a 75kg man).

If you are starting treatment for subclinical hypothyroidism, this article advises starting at a dose close to the full treatment dose on the basis that it is difficult to assess symptom response unless a therapeutic dose has been trialled.

[Imaaan]

Many moons ago upon diagnosis, I was prescribed 50 mcg and worked myself up over the yrs. Anything above 75 has given me severe excruciating chest pain, so I'm grateful to God that I started slowly

[buddy99 in reply to Imaaan]

Thank you, Imaan. I have received more info from this person (her T4 and T3 are way below range) and I am more and more convinced that she should be started slowly because of these blood results and her age. If one is in such bad shape as far as thyroid hormones are concerned and elderly, going full throttle is probably more of shock to the system than enduring the hypo symptoms a bit longer but letting the body adjust to the new situation. She will have to talk to her doc about those concerns.