Unusual thyroid results

Re: Unusual thyroid results

Kara Gibson — Wed, 25 Mar 2015 09:38:39 GMT

Thank you Shanley, I will look into this!

Re: Unusual thyroid results

shanley barber — Tue, 24 Mar 2015 20:11:50 GMT

I had a spaniel with endothelial dystrophy that sounded like this, many years ago. We treated it for several years with a hyperosmotic drop (can't remember what it was) to reduce the corneal oedema. The thyroid may be unrelated, so I would work them up separately. Hope this helps, Shanley

Re: Unusual thyroid results

Kara Gibson — Tue, 24 Mar 2015 01:51:24 GMT

That's the bit I'm confused about, the antibodies are given as a percentage but the ref range is <200, it doesn't make any sense. I have asked the lab and I'm waiting for a response! As far as I can tell usually antibodies are given as a percentage and over 35% is usually positive.

Re: Unusual thyroid results

Stephen Courtney — Sat, 21 Mar 2015 18:02:24 GMT

Of course hypothyroidism is also common in the breed...but it can be a nightmare to prove. I read the autoantibodies as 93 with normal less than 200 - is that right? In which case are the antibodies high at all?

Re: Unusual thyroid results

Stephen Courtney — Sat, 21 Mar 2015 17:59:33 GMT

What about age related corneal dystrophy? You get attenuation of the endothelial layer resulting in increasing levels of corneal oedema,which can lead to bulls lesions / vesicles over time, which often present as ulcers. common in the breed. Uveitis is painful and has other signs, what you describe seems to be a corneal issue only, but of course it can be hard to see through these corneas...

Re: Unusual thyroid results

Christopher Saul — Sat, 21 Mar 2015 08:27:06 GMT

Hi Kara,

I assume this dog has not had any treatments with drugs that can interfere with thyroid function tests (principally steroids, TmpS or phenobarbital)?

The sensitivity of the FT4ed is quoted in the range 80-98%, which means that 2-20% of hypothyroids will have FT4ed within the reference range (albeit low within that range); and your value is indeed low within the range.

That said one could also argue that the specificity of the TSH is similar (think about 80-95% off the top of my head) and argue the opposite BUT in your dog's case the TSH is not borderline it's comfortably high.

What was the reference lab's value for TT4? ( IMO in house machines are not the most reliable) - might be useful to ask them to run this if you have't already.

Did your biochemistry panel include triglycerides or cholesterol? these are frequently high in hypothyroidism.

So; given no test is 100% accurate we have to rely on clinical judgement to some extent. Occular changes are occasionally seen with hypothyroidism and these would include corneal lipidosis, lipaemia retinalis, corneal ulceration and uveitis, so your dog's clinical signs certainly are suspicious. Were there any other clinical signs?

On balance, it seems to me that your dog is likely hypothyroid. With equivocal results my usual advice would be to re-test in a month or so but this dog has ongoing uveitis and needs treatment.

Therefore - assuming that your reference lab's TT4 value is low (or low in the reference range) and the dog has had no drugs which can interfere with thyroid function - I would advise trial treatment in this case.

Hope this helps

Chris