1. Liothyronine treatment in hypothyroidism
Dr John Clark

2. Thyroid Treatment Synthetic thyroxine available in 1950s
Previously used porcine thyroid extracts which were not physiological
Porcine ratio T4:T3 is 4:1
Human ratio T4:T3 is 14:1

3. Over-replacement Occurred in the 1970s and 80s with thyroxine alone
Now have more accurate TSH level
Predisposed to atrial fibrillation + osteoporosis

4. On Thyroxine but still symptomatic
Have FT4 and TSH returned to normal?
If TFTs normal check for other pathology
Particularly other auto-immune conditions
Was TSH definitely elevated at diagnosis? (remember pituitary disease)
Consider checking FT3 if nothing else present to explain symptoms

5. Normal FT4 and TSH but low FT3 (on thyroxine alone)
No other pathology and patient has significant symptoms
Consider referral to Endocrine Service to discuss possible combination therapy (T4 + T3)

6. Normal FT4, FT3 +TSH (on thyroxine alone)
No other pathology and patient has significant symptoms
Are patients symptoms “psychological” rather than endocrine?
Possibly refer to Endocrine Service to discuss combination therapy (T4 + T3)

7. Combination Therapy Only do as a trial – supervised by endocrinologist
Usually require 25-50ug reduction in thyroxine
Add in liothyronine 5ug bd
After 6 weeks are all TFTs normal and is patient feeling any better?

8. Combination Therapy Evidence of benefit in trials – none
British Thyroid Association 2016
“Can do in very small number of appropriately selected patients, who have unambiguously not benefitted from thyroxine treatment”

9. Cost Liothyronine was £5/month, now £400/month Reason?
As a consequence I very rarely prescribe it
But Europe!
Armour extract

10. Replacing liothyronine with thyroxine
Clinically relatively straightforward
Psychologically very difficult - dependancy

11. Summary
99% of hypothyroid patients will do well on thyroxine treatment alone
The remaining 1% - liothyronine “unavailable” due to cost - ? Europe
Can patients already on liothyronine have it replaced with thyroxine? Yes – if patient agrees.