Brief Answer:
Thyroid

Detailed Answer:

If your thyroid blood test results done periodically over time, suggest steady TSH and Free T4 levels then there is no harm done in taking thyroxine 86 mcg daily.

There are couple other things to comment on here:

1 My impression is that thyroxine is typically available in 88 mcg and not 86 mcg. But I do not rule out the possibility that it may be manufactured in Australia in this dose strength. At any rate it does not matter much as it is a very minor difference of only 2 mcg

2 Taking thyroxine for hypothyroidism is beneficial, provided the diagnosis of hypothyroidism is correct. Endocrinologists are most qualified to do so. We typically go by several pieces of evidence before committing an individual to life long thyroxine treatment. Some examples include:
a) Positive thyroid auto antibodies such anti TPO (thyroid peroxidase) and/or anti Thyroglobulin

b) Thyroid swelling ('goiter')

c) Family history of thyroid problems

d) Symptoms suggestive of hypothyroidism.

e) Significantly elevated TSH blood test result at baseline or during the course of treatment

These are some example of factors taken into consideration jointly before a final diagnosis is made

3 So if you truly have Hypothyroidism then the next step is to get the thyroxine dose right for the rest of your lifetime
This entails initial 6 to 12 weekly blood checks and once stable biannual or even annual tests suffice

4 The typical TSH target I use for my patients is 0.4 to 2, with free T4 closer to the higher end of the normal range.

However,there are a few situations where the thyroxine dose should be more conservative such as
a) severe untreated osteoporosis
b) chest pains from blocked arteries in the heart
c) Irregular heart beat rhythm problems

5 So as long as your TSH and free T4 remain at goal, you are unlikely to experience any harm from taking thyroxine for a lifetime

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