Hyperthyroidism and raw food diet

Hello. I have a 8 years old female calico cat and a 12-13 years old male short hair cat and both are found with high levels of T4 ( T4 2.8 on male cat and T4 2.7 on younger female);
vet also wanted to run the Free T4 and that came back up pretty high as well, so...looks like we're might be going to deal with hyperthyroidism pretty soon.
my cats are on raw meat diet + I add some Ziwipeak and Nature's Variety canned food (for flavor, texture and to better entice their appetite) for more than 4 years now and doing great but I did notice a rapid incresed of the T4 levels and Cholesterol (also pretty high!) in the last couple of years.
I used to grind up turkey thighs (Perdue brand) with some chicken but, for some reason, I can't find turkey in stores anymore so I started feeding a whole course ground rabbit (that I can easily get from MyPetCarnivore in Indianapolis) with some chicken .

My question is: could hyperthyroidism be caused by or related to this diet?

The rabbit I use for the recepie does include the thyroid gland and other organs so I do not add any extra iodized salt on the batch; could it be because the rabbits are fed in a way so they carry a high content of iodine...?!

I find it kind of odd the both cats T4 levels raised that much lately and I'm triyng to figure out what the cause is; I'm afraid it's my fault beacause of what I'm feeding them....or could it be stress?

P.S.: besides the T4, high Cholesterol and high level of proteins, everything else look pretty good on their blood work; although, their appetite increased and, while the younger female is keeping the same weight and same behavior, the older male has been more vocal, restless at times and seems to me he has lost some muscle mass especially around his thighs but keeping about the same weight for now; he was also found with a slight heart murmur recently and hopefully that is caused by the overeacting thyroid ( will have to go see a cardiologist soon).

And, did anybody try to treat Hyperthyroidism with an holistic approach?
Can huperthyroidism be reversed naturally?

ANY THOUGHTS, RECOMMENDATIONS OR HELP WOULD BE GREATLY APPRECIATE, THANKS

Likely unrelated. Hyper-t is very, very common in cats older than 10. Your cats are low grey zone right now, it may take awhile for them to go into proper hyper-t, but it's worth watching. Raw food is no doubt the best diet you can offer your cats. There isn't any solid evidence as to what causes hyper-t but there is some evidence that it is possibly related to foods (fish, BPA) as well as environmental chemicals.  

There are NO holistic or natural treatments for hyper-t. Hyper-t is caused by a tumor growing on the thyroid and there is no way to slow down or reverse it other than with i-131, which is the cure. You can also do meds, but ultimately meds just mask the symptoms and the tumor will continue to grow. I did i-131 on my 13.5 year old when he was diagnosed back in January of this year with a T4 of 5. He recovered perfectly and now has a normal T4. 

Just a quick question on the raw diet.  Did you ever use Call of the Wild to supplement with?  There was something going around a couple years ago that they were pretty high in Iodine, and the thought was that that might eventually lead to Thyroid issues.  I quit using it because of that.

Just curious.

I think you mean "Taste of the Wild" but, no, I haven't tried as it never appealed to me. Good catch on that though, I'm going to ask Ziwipeak and Nature's Variety companies if they can tell me the content of Iodine on their canned food.
Although, I just came accross something else pretty disturbing; I've always use Ball mason jars to can the food and was thinking about the lids and the possibility of BPA....guess what?! Looks like many of the Ball's lids (probably the older ones) are NOT BPA free and I have several of them.
Please take a look at the article below and tell me what you think.
I really hope I didn't make my kitties sick 8-(

https://delishably.com/misc/How-to-Can-Food-BPA-Free-Mason-Jar-Lids-are-Toxic

Blakat said:

I think you mean "Taste of the Wild" but, no, I haven't tried as it never appealed to me. Good catch on that though, I'm going to ask Ziwipeak and Nature's Variety companies if they can tell me the content of Iodine on their canned food.
Although, I just came accross something else pretty disturbing; I've always use Ball mason jars to can the food and was thinking about the lids and the possibility of BPA....guess what?! Looks like many of the Ball's lids (probably the older ones) are NOT BPA free and I have several of them.
Please take a look at the article below and tell me what you think.
I really hope I didn't make my kitties sick 8-(

https://delishably.com/misc/How-to-Can-Food-BPA-Free-Mason-Jar-Lids-are-Toxic

Click to expand...

No, I do actually mean CALL of the Wild, but that's incidental at this point. 

As to the Ball lids, are you actuallly canning the food, or just freezing it?  If freezing it, I'm guessing the food isn't actually touching the lid, is it?  If not, it's probably ok.  I used to freeze all mine in small ziploc bags or those "disposable" glad containers, so am guessing they were a LOT worse for them.  Never gave it a thought   (until now). 

I wouldn't blame myself for this if I were you.  Sounds like you've done everything you could to the best of your ability to do what's best for your little ones

The food I make for my cats is usually not touching the lid (not sure if BPA contamination would happen by contact or not though...)
Update on Ball canning lids: just got off the phone with a lady from the Ball company and assured me that all of their lids are BPA free since the 60' when the company came up but recently they started printing "Mada in Usa" on lids...
I really hope that's the truth and the article I found online is wrong ....

Thank you, I also agree that I131 is the best and safest way to take care of hyperthyroidism. Just hope that moment is still pretty far...