The whole area of TSH testing has been discussed, criticised, acclaimed, and generally confused for years. Here is an interesting article which is, in my view, well worth reading.
Thyroid-Stimulating Hormone
Why Efforts to Harmonize Testing Are Critical to Patient Care
By James D. Faix, MD, and Linda M. Thienpont, PhD
Thyroid disease is common in the general population, and its prevalence increases with age. Because the signs and symptoms of the disease often resemble other disorders, before initiating treatment physicians need to determine whether the patient actually has thyroid disease or something else. The test most frequently ordered to test thyroid function is thyrotropin, commonly referred to as thyroid-stimulating hormone (TSH). Based on the functional interrelationship of the hypothalamus, pituitary gland, and thyroid, TSH should be elevated if the thyroid gland is not producing adequate thyroid hormone, and suppressed if it is producing too much (Figure 1). Today, however, we are beginning to realize that this well-established paradigm for TSH synthesis and release is an oversimplification.
The part about glycosylation is very interesting. An Endo in USA told me about this stuff and how it acts like a turbocharged form of TSH and was normally found in , I think I recall, patients who had been hypo and untreated for a long time.
Interesting to know more. Does TSH go high and as it stays high then thyroid switches to the high potency form or is it the action of TPO abs?
This report seems to say that tests are blind to glycosylation which on one hand is good but on the other means that a euthyroid well persons TSH of 2 if seen
In a hypothyroid person could be understating how hard the thyroid is being driven by the pituitary.
Wonder if this is why we feel ill for a long time before we finally go over the limit and get treated? If so then TPO needs testing on symptoms not TSH levels....?
Having read this paper: jcem.endojournals.org/conte... (about the production of T4, T3 and TSH in 'normal individuals) I am a bit stuck on understanding the role of T4 as a negative modulator in the TSH production process. Another point mentioned on the forum is that folks taking T3 have very low TSH. Surely T3 is the major negative modulator?? Which T3 of course, circulatory or hypothalamus/pituitary produced. Circulatory seems to be a modulator of TSH if you take it by mouth?? In the paper above how come that T4 is constant as TSH increases whereas T3 production is strongly linked to TSH production??
There was another paper very, very recently (I saw it after that one) which went on about tanycytes (mentioned in that paper) seem critical to controlling dietary intake and putting on weight.
My immediate reaction was to question whether thyroid and weight are both affected by problems of tanycytes?
Wow - my brain feels frazzled now after trying to read all those articles. Can anyone summarise them in layman's terms? I want my family to get tested due the genetic factor. I'm 46 and found out a year ago that I have Hashimoto's and subclinical hypothyroidism, now on 50mg Levothyroxine. My mum (71) went to the doctors the other day and he said he would only do the TSH test. Mum noticed that he put "daughter has Hashimoto's" on his notes or the blood test form. I don't think he's even going to do the T4! Some of her symptoms include: loss of hair, overweight, bad back for years so on diclofenac - NSAID and fallen arches, very dry cracked skin on hands and feet, dry eyes and sinus problems. She isn't yellow like me and seems to be okay in the cold. My dad's sister is treated for hypothyroidism and had nodules cut off from her thyroid gland many years ago. She's also on anti-depressants. Her son is treated for schizophrenia and depression. I think he's on lithium now! My dad (71) doesn't complain about being tired but will fall asleep anywhere and often. He gets acid reflux, gout and snores, his eyes water a lot (a sign of dry eyes?). He's also doesn't have yellow skin and can deal with the cold. His skin is okay too - not dry. He also has another strange symptom where he can faint after eating. This is rare though. He will also ask for tests but is waiting for his knee to get better after twisting it. He's on crutches now and can't drive. Is there a simple print out or suggestions for him getting tested for TSH Free T4, FreeT3 and antibodies. Thanks xx
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