Rectum temperature much higher than under the tongue temperature

[Callmestar]

I've had hypothyroid type symptoms for years and more recently had a high TSH of 8.6. I'd been taking my temperature via under the tongue and it was always low. Typical 36.0c/96.8f upon waking. This morning I thought I'd try tongue and then rectum after reading quite a bit about the rectum probably being more accurate.

My under the tongue temperature was 36.1c and my rectum temperature was 36.7c? Clearly a massive difference with one suggesting I'm very cold and hypo and the other suggesting I'm relatively normal.

Confused

 

[xeliex]

Rectal temps typically are higher indeed around 0.5 degrees.
Go by the oral reading and keep trying to raise it a little.
My daytime oral temps are great but the mornings just don't change much despite thyroid meds.

 

[haidut]

I've had hypothyroid type symptoms for years and more recently had a high TSH of 8.6. I'd been taking my temperature via under the tongue and it was always low. Typical 36.0c/96.8f upon waking. This morning I thought I'd try tongue and then rectum after reading quite a bit about the rectum probably being more accurate.

My under the tongue temperature was 36.1c and my rectum temperature was 36.7c? Clearly a massive difference with one suggesting I'm very cold and hypo and the other suggesting I'm relatively normal.

Confused

Serotonin, which is mostly produced in the gut, can raise rectal temps and rectal temp is in fact one of the methods of assessing serotonergic activity of substances in animal experiments. The difference in this case is small, so not saying it is due to serotonin, but for a larger discrepancy it may be applicable. That's why armpit (core) temps may be a better temps assessment than other areas. Rectal temps are mostly used on toddlers, as their serotonin is low and rectal temps are good surrogate of core temps as well.

 

[Blaze]

I've had hypothyroid type symptoms for years and more recently had a high TSH of 8.6. I'd been taking my temperature via under the tongue and it was always low. Typical 36.0c/96.8f upon waking. This morning I thought I'd try tongue and then rectum after reading quite a bit about the rectum probably being more accurate.

My under the tongue temperature was 36.1c and my rectum temperature was 36.7c? Clearly a massive difference with one suggesting I'm very cold and hypo and the other suggesting I'm relatively normal.

Confused

Rectal temps have always been the most accurate way to measure and give a much better approximation of core temps. The only reason it is not used more is the discomfort factor. Patients will always prefer the oral temp method or the infrared temps taken by scanning the forehead.