7 reasons why your TSH may be increasing

If you are a thyroid warrior and noticed your TSH increasing... let's investigate.

I have had doctors tell my clients, "Your labs look great. See you next time" but in reality their TSH has been steadily increasing over the last 2 years going from 1.5 to 1.7 and then up to 3.5 (see graphic below for normal ranges). Could it be because she's working out more and not eating enough for the amount of energy she's expending? Could she still be using endocrine disrupting household items? Could her autoimmune disorder be causing underlying inflammation resulting in elevated reverse T3?

In this article, I'm helping you understand what could possibly be going on when there is an increase in TSH. Please note that lab interpretation needs to be done by a health professional.  Please reach out to your doctor, nurse practitioner, or dietitian for further guidance. 

*This article is for educational purposes only

                        * All lab data from mayocliniclabs.com

Why is your TSH increasing?

TSH stands for Thyroid Stimulating Hormone and is actually produced by the pituitary gland in the brain. TSH stimulates the thyroid to make T4 and T3. T4 is the inactive thyroid hormone and needs to be converted by the body into the active form of T3. 

Many people have labs in the normal range but are still struggling with hypothyroid symptoms. Two oversights that can happen in reviewing a lab is not monitoring trends and the other is utilizing supporting labs to assist with the interpretation of that lab. 

Let's review why someone's TSH may be increasing and why you're still having hypothyroid symptoms, even when labs are in normal limits. If you see an increase in TSH and don't feel well, still struggling to lose weight, have thinning hair, or other symptoms... it's time to investigate to figure out what could be happening. 

Below you'll find 7 reasons your TSH may be increasing. 

1) TSH increased because of low T3

T3 is the active thyroid hormone. I like to think of it as the gas pedal to the car. If you want the car to go faster, you need more T3 and for that T3 to actually activate a T3 receptor site. When T3 is low in the blood, your pituitary gland will become activated to make more TSH.   Just because a lab is in the normal range doesn't mean it's your normal. 

                           * All lab data from mayocliniclabs.com

Let's do a case study.

40 year old female with T3 of 2.3 pg/mL and increased TSH of 4.7 mlU/L.  If you look back on the trend, it T3 was 3.5 pg/mL the year before. TSH of 4.7 is just slightly elevated but elevated enough to have symptoms of weight gain, thinning hair, exhaustion, anxiety, and digestive issues. Even though both labs are not that far out of range, people feel the difference. Now we need to figure out WHY this is happening. 

Is low T3 caused from:

•  Could a low T3 be caused because of a conversion disruption? Once the thyroid is stimulated by TSH, it makes mostly T4 and a little bit of T3. This means the body still has to convert T4 to the active T3. If there is a disruption in the conversion, then the TSH will be elevated due to low T3. Low T3 is exhaustion, constipation, etc... it the metabolism us thyroid warriors are desperately seeking out.
  
  
  •  Causes of poor conversion of T4 to T3 may be due to fatty liver (alcoholic or non-alcoholic fatty liver) or elevated LFTs (liver function tests). You will be surprised by how many people actually have some sort of liver dysfunction starting. The liver is responsible for removing one of the iodines from T4 to make T3 (1). However, if liver damage is present - this important conversion to T3 may suffer resulting in low T3 levels. 
    
    
  • Another cause of low conversion of T3 could be a lack of tools. This is where eating certain foods to support your thyroid comes into play (see list below).  Iodine, selenium, zinc, iron, and carbohydrates either play a role in thyroid hormone metabolism or influence the metabolism of thyroid hormones. Both anemia and low carbohydrate intake (2) have been shown to decrease conversion of T4 to T3.
    
    
  • Elevated estrogen/estrogen replacement therapy causing elevated TBG (Thyroxine binding globulin). TBG binds to thyroid hormones in the blood, therefore an increase in TBG results in a decrease in thyroid hormones (3). That means your body doesn't receive what it needs. 
    
    
• Could low T3 be caused from high reverse T3 (rT3)? RT3 is the mirror image of T3 and unlike it's helpful counterpart, rT3 is completely useless and does not activate the T3 receptor site. When rT3 is elevated it is inversely related to T3. However, like you see above, a low T3 does not always mean a high rT3. Repeat- rT3 will cause a low T3 but a low T3 does not always mean rT3 will be high.
   
  • Causes of high rT3 include calorie restriction (I'll say it again- 1200 calories is not enough for an adult), chronic inflammation (do you have an autoimmune disorder or massively stressed/not sleeping?), cancer, trauma/stress etc (4). rT3 is not used by many people to help investigate what's going on, in fact the Thyroid.org does not recommend it in diagnosing of hypothyroidism or hyperthyroidism. However, we're not trying to diagnose. A diagnosis has already occurred with the elevated TSH and low T3 by the doctor and I, as a dietitian, can not diagnosis but I can figure out if we need to look into some's inflammatory markers or look more into someone's Omega 3 fatty acid intake is meeting the demand of the body. Supporting labs can help me look more into seeing if someone is eating enough for their energy expenditure (because cutting calories does not always work for thyroid warriors).