2. Introduction
Hypothyroidism prevalence is gradually increasing throughout the world.
prevalence was 10.95% in India
ATA does not endorse the prescription of T3, BTA and ETA propose its usage in a select group
of patients who do not respond to T4
Unnikrishnan AG, Kalra S, Sahay RK, Bantwal G, John M, Tewari N. Prevalence of hypothyroidism in adults: An epidemiological study in eight cities of India. Indian J Endocrinol Metab
2013;17:647-52
. Jonklaas J, Bianco AC, Bauer AJ, Burman KD, Cappola AR, Celi FS, et al. Guidelines for the treatment of hypothyroidism: Prepared by the American Thyroid Association Task Force on
thyroid hormone replacement. Thyroid 2014
. Wiersinga WM, Duntas L, Fadeyev V, Nygaard B, Vanderpump MPJ. 2012 ETA Guidelines: The use of L-T4 + L-T3 in the treatment of hypothyroidism. Eur Thyroid J 2012
Okosieme O, Gilbert J, Abraham P, Boelaert K, Dayan C, Gurnell M, et al. Management of primary hypothyroidism: Statement by the British Thyroid Association Executive Committee. Clin
Endocrinol 2016
3.
4. continued symptoms including fatigue, in spite of optimized T4 dosage.
Tissue hypothyroidism can also manifest as surrogate markers of the
syndrome, including raised liver enzymes and CPK (creatine
phosphokinase), as well as dyslipidaemia.
T3 has been used in euthyroid conditions like cardiac surgery, depression
and fibromyalgia.
Kalra S, Khandelwal SK. Why are our hypothyroid patients unhappy? Is tissue hypothyroidism the answer? Indian J Endocrinol Metab 2011;15(Suppl
2):S95-8
5. indications
proven absolute deiodinase enzyme deficiency,
allergy/hypersensitivity to all T4 preparations.
combination may be used as the initiation of treatment in severely
symptomatic patient
Interchange is mandated in patients who have achieved biochemical
euthyroidism, but continue to exhibit clinical or biochemical signs of
the disease. Examples include low satisfaction/well-being, thyroid fatigue
syndrome and surrogate biochemical anomalies linked with
hypothyroidism such as raised liver enzymes and dyslipidaemia.
Dayan C, Panicker V. Management of hypothyroidism with combination thyroxine (T4) and triiodothyronine (T3) hormone replacement in
clinical practice: A review of suggested guidance. Thyroid Res 2018;11:1.
6.
7. Contraindications
contraindications –
1. women planning conception
2. antenatal
3. lactating mothers.
avoided - unstable heart disease and severe osteoporosis.
potential for misuse as a weight-reducing drug
8. monotherapy, or as combination therapy.
The T4:T3 ratio must be decided while prescribing combination thyroid
replacement.
While introducing T3 into a pre-existing prescription of T4, it is important
to decide whether to continue the same dosage of T4 or to reduce it.
9. Intensification is preferred in people who continue to have biochemical
hypothyroidism (high TSH with/without low T3) in spite of a ‘reasonable’(1.5–
2 µg/kg/day) dose of T4 for an adequate (6–12 weeks) period of time. In
cases, a 20 µg dose of T3 may be added to the T4 prescription.
no consensus on the ideal ratio of T4 to T3.
10:1 ratio -with further titration done on an individualized basis.
Dayan C, Panicker V. Management of hypothyroidism with combination thyroxine (T4) and triiodothyronine (T3) hormone replacement in clinical practice: A
review of suggested guidance. Thyroid Res 2018
10. T3 may be required in a twice-daily dose in some persons.
Titration of dosage may be done in 6–12 weekly intervals.
The triggers for titration will depend upon the indication for starting T3
therapy.
If symptoms were the reason for T3 initiation, these should be enquired
about.
If biochemical reports were the reason, these must be reviewed.
In case a finite endpoint is achieved, e.g., euthyroidism, to facilitate an
elective surgery, the need for continued T3 intake should be reevaluated.
11. In such cases, a detailed clinical evaluation should be performed to reason
the cause of the concern or complaint.
The 6-dimensional approach to refractory hypothyroidism provides a
pragmatic framework for this.
Persons who respond to T3 therapy may continue their treatment
indefinitely
Kalra S, Narayanan P, Monteiro AS. A 6 Dimensional approach to diagnosing refractory hypothyroidism. Thyroid Res Pract
2020;17:53-5.
12. Evidence and experience
Multiple studies have been conducted on the efficacy of T3 as opposed to
T4. The results are equivocal. If there is no added benefit of using T3 at a
population level, there is no added disadvantage as well.
The large numbers of persons living with hypothyroidism who complain of
dissatisfaction, the understanding of concepts such as tissue
hypothyroidism and the realization that genetic factors like deiodinase
deficiency may impair the action of T4, suggest that we need to think
beyond convention.
13. Special care should be taken in women of childbearing age who are not
on contraception, the elderly and those at risk of/with established
cardio-vascular disease and osteoporosis .
misuse of the drug for inappropriate indications, such as obesity, heart
blocks or depressive symptoms.
14. Contraindications and
caveats/concerns for T3 therapy
Pre-conception/pregnancy/lactation
Unstable coronary artery disease/pericardial effusion/arrhythmias
Severe osteoporosis
Potential of abuse for weight loss
Sick euthyroid syndrome (low T3 with/without other abnormalities)
15. rational manner,
choosing the right patient, who is followed up with due diligence and
vigilance.
? ideal dosage and frequency of administration.
