Work out percentage : My maths is dreadful! Can... - Thyroid UK

Thyroid UK

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Work out percentage


My maths is dreadful!

Can someone tell me what equation to use to work our percentage through range.

I’d really like to know for my T4 before I go and see the dr again to request a dose increase. It looks like my T4 is just under half way through but I’d like to be able to calculate it properly.

Serum free T4 level 16.8 pmol/L [11.0 – 23.0]

Serum TSH level 1.6 mU/L [0.27 - 4.5]


6 Replies

Does this help?

MissSusan in reply to humanbean

Perfect! Thank you so much.


Take the bottom of range (11.0) from the top of range (23.0) which gives you the size of the range (12.0).

Take the bottom of range (11.0) from your result (16.8) which gives you the displacement from the bottom of range (5.8).

Divide the displacement (5.8) by the size of the range (12.0) which gives 0.4833333333333. Make it a percentage by multiplying by 100 which gives 48.33%.

4.5 - 0.27 = 4.23

1.6 - 0.27 = 1.33

1.33/4.23 = 0.3144

0.3144 * 100 = 31.44%

MissSusan in reply to helvella

Thank you!

Try this one. Just put in your numbers.


So you need dose increase in Levothyroxine

See GP

Ask GP to test vitamin D, folate, ferritin and B12 too

Have you had TPO and TG thyroid antibodies tested? If not, ask for this test too

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