Another useful article showing minimal adverse effect dosing with T3 in addition to T4

[diogenes]

This downloadable paper has studied the effects of T3 administration on women with some residual thyroid working. T3 in combination gave better health signs when T4 only was given in therapy. T3 only therapy is still a step medicine won't yet tread, but at least combination therapy is now seriously looked at

ORIGINAL RESEARCH article

Front. Endocrinol., 22 February 2022 | doi.org/10.3389/fendo.2022....

Effect of Liothyronine Treatment on Quality of Life in Female Hypothyroid Patients With Residual Symptoms on Levothyroxine Therapy: A Randomized Crossover Study

Betty Ann Bjerkreim1,2*, Sara Salehi Hammerstad3,4, Hanne Løvdal Gulseth5, Tore Julsrud Berg1,2, Lars Johan Omdal6, Sindre Lee-Ødegård7 and Erik Fink Eriksen3,8

1Department of Endocrinology, Morbid Obesity and Preventive Medicine, Oslo University Hospital, Oslo, Norway

2Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway

3Department of Endocrinology, Pilestredet Park Specialist Center, Oslo, Norway

4Department of Pediatrics, Oslo University Hospital, Oslo, Norway

5Department of Chronic Diseases and Ageing, Norwegian Institute of Public Health, Oslo, Norway

6Department of Endocrinology, Balderklinikken, Oslo, Norway

7Department of Transplantation, Oslo University Hospital, Oslo, Norway

8The Faculty of Dentistry, University of Oslo, Oslo, Norway

Objective: The effects of levothyroxine (LT4)/liothyronine (LT3) combination therapy on quality of life (QoL) in hypothyroid patients former on LT4 monotherapy have been disappointing. We therefore wanted to test the effects of LT3 monotherapy on QoL in hypothyroid patients with residual symptoms despite thyroid stimulating hormone (TSH) values within the reference range.

Design: Female hypothyroid patients with residual symptoms on LT4 monotherapy or combination LT4/LT3 therapy received LT3 and LT4 monotherapy, respectively for 12 weeks in a non-blinded randomized crossover study.

Methods: Fifty-nine patients aged 18-65 years were included. QoL was assessed using one disease-specific questionnaire (ThyPRO) and two generic questionnaires (Fatigue Questionnaire and SF-36) at baseline and at the end of the two treatment periods. Clinical indices of cardiovascular health (resting heart rate and blood pressure), as well as thyroid tests, were assessed at baseline and at the end of the two treatment periods.

Results: After 12 weeks of LT3 treatment, 12 of the 13 domains of the ThyPRO questionnaire (physical, mental and social domains) showed significant improvements. The most pronounced improvements were less tiredness (mean -21 ± 26; P<0.0001) and cognitive complaints (mean -20 ± 20; P<0.0001). LT4 monotherapy exerted minor effects on two domains only (cognitive complaints and impaired daily life). All three dimensions’ scores in the Fatigue Questionnaire (physical, mental and total fatigue) improved after LT3 treatment compared to baseline (P<0.001), and in the SF-36 questionnaire 7 of 8 scales showed significantly better scores after LT3 treatment compared to baseline. There were no differences in blood pressure or resting heart rate between the two treatment groups. TSH in patients on LT3 was slightly higher (median 1.33 mU/L (interquartile range (IQR) 0.47-2.26)) than in patients on LT4 (median 0.61 mU/L (IQR 0.25-1.20; P<0.018). Five patients on LT3 dropped out of the study due to subjectively reported side effects, compared to only one on LT4.

Conclusions: LT3 treatment improved QoL in women with residual hypothyroid symptoms on LT4 monotherapy or LT4/LT3 combination therapy. Short-term LT3 treatment did not induce biochemical or clinical hyperthyroidism, and no cardiovascular adverse effects were recorded. Further studies are needed to assess the long-term safety and efficacy of LT3 monotherapy.

Clinical Trial Registration: ClinicalTrials.gov, identifier NCT03627611.

[shaws Administrator]

Thank you diogenes. That is very encouraging for those hypo patients who remain very symptomatic.

[tattybogle]

very encouraging . thankyou for letting us know

[SarahJane1471]

Now that I like 👏

[helvella Administrator Thyroid UK]

Note that they did their blood tests using a very similar approach to that often expounded here:

Laboratory Assessment

All blood samples were collected in a fasting state in the morning before medication was ingested, approximately 24 hours after the last LT4 dose and 14 hours after the last LT3 dose.

And, despite using an initial dose ratio of approximately 3:1 (T4:T3 by weight), adjusted - if needed, the patients' TSH was actually higher on T3.

[jimh111]

Thanks for this. The level of significance is outstanding given the small number of participants. Unfortunately, the study was not blinded, rendering it of little use. I'm not shooting the messenger!

There are all sorts of excuses for not being ‘able’ to blind the study but if they put some effort in it could have been achieved. Could they not crush the standard tablets and put them in little packets? We see this sort of laziness in the medical world all the time, it would not happen in the manufacturing industry or other businesses.

Sorry for the rant. I hate to see precious medical resources being wasted.