High dosage thyroid replacement should be considered in 'refractory' hypothyroidism
High dosage thyroid replacement should be considered in
There has been correspondence in the British Medical Journal
(8th February 2003) discussing tangentially risk assessment in patients
receiving high dosage thyroid replacement. As my practice is mainly
concerned with problems of thyroid function, I seek advice from colleagues
on the advisability of long term high dosage thyroid replacement in
patients with refractory hypothyroidism.
Hypothyroid patients who do not respond to thyroid treatment comprise
two groups namely patients who show no improvement but become clinically
thyrotoxic and patients who show no improvement nor adverse effect. The
latter creates a frustrating and difficult situation for both patient and
doctor which is often compounded by FT4 or FT3 levels above the upper
limit of the 95% reference interval and TSH levels approaching zero.
During the last decade I have treated at least fifty patients who had
irresolvable or refractory hypothyroidism with sodium thyroxine at dosages
over 350µg per day or natural Armour Thyroid extract at over 4 Grains per
day or a combination of the two medications at equivalent dosage. These
patients have been returned to optimal or near optimal health with no
evidence of adverse effect.
The critical question concerns possible long term adverse effects. A
priori, it is unlikely that restoration of a patient to health where she
is up and about and living a full life will be detrimental or associated
with long term pathological sequelae. Perceived complications are
unproven. Cardiac irregularity is a well recognised feature of
hypothyroidism and usually disappears on thyroid replacement and (in my
experience) asymptomatic thyroxine induced irregularity is rare but is
easily detected by physical examination and is reversible within 1-2 days.
Evidence of osteoporosis is insecure and may have arisen from the
purported association of osteoporosis with chronic hyperthyroidism where
there may also be accompanying hyperparathyroidism with bone
demineralisation but this is speculation. The author has never encountered
significant adverse effects in patients restored to euthyroidism by high
dosage thyroid replacement.
There is a second more philosophic consideration; many patients
unequivocally state that they would rather run the gauntlet of putative
and unproven pathological sequelae than continue a wretched hypothyroid
existence. This raises an ethical question on the degree of self
determination or self selection of medical care which is desirable,
acceptable or indeed is a patient¹s right in a society based on consensual
rather than dictatorial principles.
However it remains an unpalatable fact that many patients are
receiving inadequate and ineffective thyroid replacement from unfounded
fears that return of a patient to euthyroidism will be accompanied by
crumbling bones or undiagnosable cardiac pathology. It is suggested that
the efficacy and safety of higher dosage thyroid replacement be subjected
to the scrutiny of formal clinical trial.
Gordon R B Skinner MD, DSc, FRCOG, FRCPath
Competing interests: No competing interests