The gland in the neck
The thyroid is gland situated at the lower part of your neck, and in simple terms is in control of your metabolism. But it’s so much more than that. And as a clinician, is frustrating and amazing to treat. Figuring out if someone has a thyroid issue is not straightforward. Many medical doctors will test TSH and declare the thyroid healthy, but this level is only a small picture of what’s going on, and their normal ranges are very different than most naturopaths.
First, let’s explore what the thyroid does and how it does it. The thyroid produces the thyroid hormones T4 and T3, which control energy utilization, heat production, and growth. T4 and T3 are produced in the gland by attaching iodine molecules to the tyrosine molecules in a complex called thyroglobulin. This thyroid hormone is released into the circulation when TSH stimulates thyroglobulin to dissolve, where it is mostly bound to carrier proteins called thyroxine-binding globulin and albumin. The hormone is then released from the carrier protein in the peripheral tissues where it is used by individual cells. Here it can have such effects as increasing heart rate, stimulating gut motility, increased speed of muscle contraction and relaxation, increased use of glucose and fats, and increased oxygen availability in the blood. So when the thyroid is functioning too high, these effects are increased. And when the thyroid is under functioning, all these things slow down. Which is actually a really good way to describe thyroid problems: hyperthyroidism speeds things up too high, and hypothyroidism slows things down too much.
Testing testing 123!
The usual level that a doctor will check to evaluate someone’s thyroid function is TSH. This is a hormone sent from the pituitary in the brain to the thyroid to tell the thyroid to get working or to cool it for a bit. It’s part of something we call a negative feedback loop. TSH turns the thyroid on, the thyroid starts making hormones, and T4 levels turn on or off TSH secretion. If T4 levels are too low, TSH will increase to tell the thyroid to make more. If T4 levels are too high, TSH will decrease and the thyroid makes less T4. So there is this continual conversation between the brain, thyroid and blood T4 levels that regulate thyroid function. When a doctor sees a high TSH level, what they see is the brain telling the thyroid to get cracking, but not enough T4 levels to turn this off, likely indicating hypothyroidism and an under functioning thyroid. If TSH is really low, then a doctor can assume that the T4 levels in the blood are very high and not responding to the low TSH level, thus indicating hyperthyroidism and an over functioning thyroid.
For the most part the thyroid produces T4, which is relatively inactive and functions like a storage hormone, and the peripheral tissues convert it into T3, which is far more active and actually has an effect on the cells. Sometimes this conversion process isn’t that efficient. This means that someone’s TSH will likely look normal, but will still experience symptoms of hypothyroidism. This is also common on synthroid, the most common medication for hypothyroidism. Synthroid is just synthetic T4. Increasing the levels of T4 addresses the conversation between the brain and the thyroid, but if conversion into the active hormone T3 is also an issue, isn’t quite fixing everything. Hence, TSH will look normal but the person will still feel hypothyroidism symptoms.
There is also a third hormone called reverse T3 (rT3) which is also relatively inactive, and this level goes up during times of stress because cortisol stimulates T3 to be converted to rT3. I will go over this more in a future post diving further into the thyroid and thyroid dysfunction.
Antibodies are also really important to test for because they indicate something is attacking the thyroid and is associated with overall prognosis. There are two main antibodies, anti-TPO and thyroglobulin antibodies. Some people will have one and not the other, but anti-TPO is the most common one. However, I have caught hypothyroidism that was only anti-thyroglobulin positive so it’s important in some cases to run both. To make matters even more frustrating, 20-30% of people who have active hypothyroidism won’t have any antibodies in their lab work because those immune cells haven’t made it out of their thyroid (yet). It’s in cases like these that a thyroid gland ultrasound is useful. These centres of autoimmune attack will show up on ultrasound imaging.
Thyroid dysfunction can be hard to pinpoint
The thyroid is an organ we don’t often think about until something goes awry. And it often goes misdiagnosed for a while because the symptoms are pretty non-specific and can look like a whole host of other things. To make it worse, testing for thyroid issues is not always straight forward because there are lots of steps in the thyroid pathway that could be contributing. Often a medical doctor will only check TSH, which is usually the last thing to change when the thyroid starts to get funky. There is a subset of people who will have symptomatic hypothyroidism, but you can’t really see it in any lab value yet. These people are best identified with an ultrasound of the thyroid to see if there is active damage occurring. There are also some people who will have hypothyroidism symptoms but the issue isn’t the thyroid but the cell’s ability to read hormone. This is called cellular hypothyroidism. In these patients, thyroid symptoms can be improved by improving cellular health.
The thyroid is also really sensitive to other things going wrong in the body, so sometimes you just have to clean up inflammation, stress, or insulin and blood sugar control in order to calm the thyroid down.
Identifying thyroid dysfunction is admittedly difficult sometimes, but identifying and treating thyroid issues can be life changing. Especially you suspect hyperthyroidism, this is not something that you should leave on the back burner!!
To wrap up this introduction to the wonderful but sometimes pesky organ, here are the symptoms of both hypothyroidism and hyperthyroidism. If you strongly identify with one of these lists and suspect that you might have a thyroid condition, please make an appointment with your naturopath or your medical doctor!
Hypothyroidism
Early symptoms –
Weight gain
Cold intolerance
Constipation
Weakness
Fatigue
Muscle and/or joint pain
Dry skin
Brittle hair and/or nails
Carpal tunnel in both hands
Tinnitus
Late symtoms –
Hoarseness
Slow speech
Decreased taste and/or smell
Puffy face
Thinning eyebrows
Skin thickening
Menstrual changes – especially irregular periods or really heavy periods
Hyperthyroidism
Early symptoms –
Fatigue
Heart palpitations
Intolerance to heat
Tremors, especially in the hand
Increased bowel movements
Vomiting
Weight loss but increased hunger
Anxiety, nervousness
Restlessness
Itching
Difficulty sleeping
Increased sweating, clammy skin
High blood pressure
Menstrual changes
Late stages –
Bulging eyes
Noticeable enlargement of throat
References
Friedman TC. Thyroid gland. Andreoli and Carpenter’s Cecil Essentials of Medicine. 63: 633-641.
Gaw A et al. Thyroid pathophysiology. Clinical biochemistry: An illustrated colour text 5th edition. 44: 88-89
LaFranchi S, Huang SA. Thyroid development and physiology. Nelson Textbook of Pediatrics 2nd edition, Chapter 563, 2663-2664.
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