Dotty, the range of 9-19 means that the test was FT4 and you are slightly over the top of the range. I have a suspicion that the retest is to see if you are over range next time and if so your dose will be reduced.
Just a heads up -
If you feel OK on your current dose of Levo, a reduction in dose would bring about a recurrence of hypo symptoms. If there is any pressure for you to reduce your dose next time, tell them that you don't feel over medicated and that it's FT3 (the active hormone) that shows if you're overmedicated. If FT3 is in range then you're not overmedicated.
From ThyroidUK's main website > About the Thyroid > Hypothyroidism > Treatment Options
'Dr Toft states in Pulse Magazine,
"The appropriate dose of levothyroxine is that which restores euthyroidism and serum TSH to the lower part of the reference range - 0.2-0.5mU/l.
In this case, free thyroxine is likely to be in the upper part of its reference range or even slightly elevated – 18-22pmol/l. Most patients will feel well in that circumstance.
But some need a higher dose of levothyroxine to suppress serum TSH and then the serum-free T4 concentration will be elevated at around 24-28pmol/l.
This 'exogenous subclinical hyperthyroidism' is not dangerous as long as serum T3 is unequivocally normal – that is, serum total around T3 1.7nmol/l (reference range 1.0-2.2nmol/l)." '
You can obtain a copy of the article by emailing firstname.lastname@example.org
Doctors won't tell you about fasting before a thyroid test, nor to leave off Levo for 24 hours, it's a patient to patient tip to give the highest possible TSH which is what is needed when looking for an increase in dose of Levo or to avoid a reduction. Most doctors dose by TSH. Always try to get the earliest appointment of the morning as this is when TSH is highest. Results can be compared accurately if conditions are the same every time.