A tissue marker like rbc-zinc may help. In typical thyrotoxicosis,
rbc-zinc is depressed. Pretty similar to the concept of HbA1c as a long
term marker of diabetes. A tissue marker represents the average thyroid
status in the preceeding 2-3 months. In transient thyrotoxicosis (e.g.
pregnancy associated, or in painless thyroiditis) the marker is normal.
This test is not widely available. Try Professor Swaminathan in Guy's
hospital. He was the one setting it up in Hong Kong originally. Some of
the laboratories in Hong Kong are still providing it. Our Endocrinologists
find it useful in difficult cases like the one you described.
Tony Mak
Clinical Pathology
Tuen Mun Hospital
Hong Kong
At 10:43 AM 1998/11/18 -0000, you wrote:
>We have a patient with some signs of thyrotoxicosis
>
>Lid retraction
>Weight loss
>
>However his thyroid function results are as follows (typical example)
>
>Total T4 70
>Free T4 19.5
>TSH < 0.03
>
>The TSH has been consistently suppressed during the last two to three
>months. Thinking this may be a T3 toxicosis we had a total T3 measured which
>came back 1t 1.50 (1.20 - 2.20).
>
>He also has strongly positive thyroid autoantibody titres.
>
>What's the next step ?
>Is this patient toxic ?
>Should we consider measuring LATS ABs ?
>What about a TRH test ?
>
>
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