My cats has diabetes and a slightly elevated T4 level?

Question

Mickey is a 12 year old Maine **** who has diabetes and she's on insulin twice a day. She's only recently started the insulin and we're having a terrible time getting her blood sugar stabilised and the vet mentioned today that her T4 levels could be interfering with the blood glucose. I need to stress that her T4 levels are barely elevated, by some lab standards she's still within the healthy range (only just though) but we've started her on meds to bring down her T4 levels and to see if a) this helps her diabetes stabilise and b) to make sure there's no underlying kidney issues (although her creatanine levels were very promising).

Has anyone else had diabetes and hyperthyroidism running concurrently in their cat/cats? And if so, did this make stabilising her blood sugar difficult?

We're retesting her in 3 weeks (to give the meds a chance to work) and then if her T4 levels are OK and kidneys are also OK, we're looking to go the nuclear medicine option. I'd appreciate any suggestions on this.

Answer 1

This is not at all uncommon; it's called sick euthyroid syndrome.  The thyroid may be entirely normal, but other illnesses cause increased (or decreased) production of thyroid stimulating hormone, thyroxine, T3, and T4.

The half life of circulating T4 is only 6-7 days at best (only 3-4 days in hyperthyroid animals), so it's not surprising that you might see a marked change quite quickly.

Best of luck to you and Mickey.