Low TSH with low FT4; FT3: 58% though range

[TW1689]

Further to my post three months ago asking for advice/comments relating to suppressed TSH readings and low FT4 readings, I enclose my latest Medichecks' results. Currently I am taking 1.5 grains of Erfa +50mcg T4 (equivalent to 104mcg T4 + 12mcgT3). Salivary Cortisols are marginal, mostly at the top of the range.

I experience arrhythmia on waking and still do not think that the "sweet" spot has been achieved.

I am particularly interested in any comments that members have have; "is low FT4 and depressed TSH a normal characteristic when using Natural Desiccated Thyroid?"

I am 77 years of age and have a very understanding endocrinologist.

[jimh111]

Your results reflect your intake. NDT contains a high T3 content. You can't rely on the T3/T4 content of the tablets to be reflected in the blood. Firstly, L-T3 is 95% absorbed whereas L-T4 has around 50% absorption. We can only guess the T3, T4 absorption rates from NDT are similar. Secondly, the fT3 figure will be very dependent upon how soon after taking NDT you have the blood taken - due to the short elimination half-life of T3.

Generally, TSH will reflect your combined T3, T4 intake. Except, many patients who need T3 have a TSH that is subnormal, their TSH is too low for their fT3, fT4 levels. In your case your TSH looks perfectly reasonable for someone taking 1.5 grain NDT plus 50 mcg L-T4. Your TSH, hormone intake and arrhythmia suggest you are taking a little too much. I would reduce to 1 grain and see whether the arrhythmia is reduced. If so, you know your hormone load is too much. This may make you feel worse but it will confirm whether or not the arrhythmia is arising from too much hormone. Once this is established you will be in a better place to make an informed decision on your hormone dose.

I'd also suggest you take a magnesium supplement such as magnesium citrate, it is good for the heart and magnesium deficiency can lead to raised blood pressure.

I'm a patient not a doctor.

[TW1689 in reply to jimh111]

Thanks for your comments; interesting and much appreciated.