What is functional hypothyroidism?

You won’t find the term functional hypothyroidism in the medical literature, or at least not yet. Primarily due to clinical hypothyroidism being bound to a rigid assessment usually diagnosed by the blood test thyroid stimulating hormone or TSH.

TSH secretion is controlled by synthesis of thyroid releasing hormone or TRH in the supraortic and supraventricular nuclei of the hypothalamus. TRH is transported to the anterior pituitary by the hypothalamo- hypophysial portal system where it stimulates synthesis of TSH. T4, T3 and TRH control the secretion of TSH (Gardner et al., 2011).

TSH production can also be affected by TSH receptor damage, medical drugs, disease states, iodide, blood glucose levels and other circulating hormones TSH may also be affected by environmental pollutants and heavy metals (Llop et al., 2015).  Metabolic disease and increases in Body Mass Index appear to be correlated with an increase in TSH levels (Ruhla et al., 2010).

Often, you will see clear links and studies to key micronutrients such as zinc, selenium, iodine and other important co-factors. These deficiencies can exist demographically but usually in westernised societies, there deficiency can be linked to impaired absorption rates, perhaps linked to digestive dysfunction and other factors.

“Measuring the amount of thyroid in the blood isn’t a good way to evaluate adequacy of thyroid function, since the response of tissues to the hormone can be suppressed (for example, by unsaturated fats) (Peat, R.1999).

 Dietary factors such as unsaturated fatty acids in the diet may potentially be one of the most overlooked factors that supress thyroid function. Other factors such as caloric restriction, stressful environments, over exercising and other factors are some of the others. It’s well known that in certain areas of hormone dysregulation such as menstrual cycle irregularities, oligoamenorrohea (loss of cycle), anovulation (failure to ovulate) and lack of libido and fertility in both men and women,  can be attributed to poor energy intake and environmental factors (Nieuwenhuijsen et al., 2014) (Skakkebæk, 2003). Dietary factors have synergy with hormonal imbalances perpetuating high levels of estrogen.

The functional suppression of thyroid function by unsaturated fats, eating a so-called healthy diet (full of uncooked brassica vegetables, nuts and seeds) orthorexic states and other factors is largely ignored by physicians.

I can say with some certainty, after completing postgraduate studies at university with a number of Doctors, that diet and inhibitory factors of diet rarely get assessed when it comes to assessing energy and thyroid function.

A persistent functional hypothyroid state, induced by unsaturated fats may lead to the pre-diabetic and diabetic states induced by an inability to utilise carbohydrate and the preferential shift to use of fats instead of sugars as suggested in the Randle or glucose fatty acid cycle (Randle, Garland, Hales, & Newsholme, 1963). Increased cortisol, oxidation, decreased carbon dioxide and an increased stress on the oxidative system, could potentially lead to glycolysis and an increase in lactic acid, further increasing damage, stress and further suppression of thyroid function.

Measurement of thyroid blood tests remains inaccurate and problematic without the inclusion of a variety of symptoms and previously accurate assessment, such as basal metabolic rate, body temperature and pulse. The suppression of both thyroid and adequate energy states will always remain.

As the common approach for diagnosing hypothyroidism is having TSH above 4 or 5 mmUL and the preferred treatment is to supplement with synthetic levothyroxine. How much change can you realistically achieve if you fail to address the supressed metabolism induced by diet, an individuals susceptibility to stress and their own environment?

 

References:

Gardner, D. G., Shoback, D. M., Greenspan, F. S. et al .(2011). Greenspan’s Basic and Clinical Endocrinology. McGraw Hill.

Llop, S., Lopez-Espinosa, M. J., Murcia, M., Alvarez-Pedrerol, M., Vioque, J., Aguinagalde, X., … Ballester, F. (2015). Synergism between exposure to mercury and use of iodine supplements on thyroid hormones in pregnant women. Environmental Research, 138, 298–305. http://doi.org/10.1016/j.envres.2015.02.026

Nieuwenhuijsen, M. J., Basagana, X., Dadvand, P., Martinez, D., Cirach, M., Beelen, R., & Jacquemin, B. (2014). Air pollution and human fertility rates. Environment International, 70, 9–14. http://doi.org/10.1016/j.envint.2014.05.005; 10.1016/j.envint.2014.05.005

Peat, R. (1999). Thyroid Therapies, Confusion and Fraud. Retrieved from www.raypeat.com/articles/articles/thyroid.shtml

Randle, P. J., Garland, P. B., Hales, C. N., & Newsholme, E. A. (1963). The glucose fatty-acid cycle its role in insulin sensitivity and the metabolic disturbances of diabetes mellitus. The Lancet, 281(7285), 785–789. http://doi.org/10.1016/S0140-6736(63)91500-9

Ruhla, S., Weickert, M. O., Arafat, A. M., Osterhoff, M., Isken, F., Spranger, J., … Möhlig, M. (2010). A high normal TSH is associated with the metabolic syndrome. Clinical Endocrinology, 72(5), 696–701. http://doi.org/10.1111/j.1365-2265.2009.03698.x

Skakkebæk, N. E. (2003). Testicular dysgenesis syndrome. In Hormone Research (Vol. 60, p. 49). http://doi.org/10.1159/000074499

 

Health, Thyroid and TSH.

Increasingly health is defined by a bunch of arbitrary numbers. High cholesterol? That’s not normal take a pill. Low iron? Here take this iron supplement. In Ivan Illich’s book, Limits to Medicine- Medical Nemesis, Illich makes the reader fully aware of his disdain of medical check ups –

” The medicalisation of prevention thus becomes another major symptom of social iatrogenesis. It tends to transform personal responsibility for my future into my management by some agency.”

Instead of heavily reliant systems on numbers and markers. Should we not look to improve qualitative and quantitative pairings to get a better picture of health and improve outcomes? The last ten weeks of my life have been wrapped up in a post graduate diploma in endocrinology. Getting a better picture of how clinicians tackle complex areas has been a rewarding but at the same time frustrating area of study.

Sometimes the questioning has been a down the lines of – This patient has this endocrine feature, what are the medication used, which medications interfere, what surgical options can be pursued and what is the follow up? What is frustrating for me is there is little effort to understand why? Why? Why Donald why? Diet, stress and environmental aspects of hormonal health are often forgotten about, because the goal of getting that client back into the window of numerical health takes priority. But what if we took a better look at the why? Might it not yield better long-term outcomes for the patient?

I have a special interest in thyroid function, motivated by the writings of Ray Peat, Broda Barnes, Mark Starr and others. There’s a significant amount of work discrediting the role of combined T4/T3 therapy and in particular natural desiccated thyroid (NDT). In many endocrine textbooks the elevation of the active form of thyroid hormone, T3 was elevated significantly post NDT treatment.

A confounding factor in this assumption was based upon a previously incorrect conversion which can still be found in endocrine textbooks stating that 1mg of NDT was equivalent to 1ug of LT-4. There is recent evidence available showing a patient preference for NDT, which showed improved outcomes to weight loss, energy, happiness, sleep and memory (Hoang, Olsen, Mai, Clyde, & Shakir, 2013).

A reliance on TSH, T3 and T4 levels alone may be ineffective at analysing the effectiveness of combination therapy in comparison to synthetic monotherapy treatment of hypothyroidism. Additionally this study highlights the inaccuracy of the assumed conversion of 1mg: 1ug. Using more accurate 3rd generation TSH assays yields a suggested ratio of 1.47 mg’s to 1ug. This may explain the lack of effectiveness in previously conducted trials and the conclusion that increased transient T3 levels were decided as unacceptable. NDT in many cases may offer a better solution than synthetic thyroid hormone after all

Potential mechanisms of improvement may also lie in the actions of T1 and T2 and assumptions based solely on TSH, T3 and T4 may not explain the benefits recorded in this and other studies.     Thyroid pic

Another pitfall of number reliance is well known in the reference of thyroid stimulating hormone (TSH). TSH is considered the gold standard for hypothyroid diagnosis but its limitations have become increasingly prevalent due to its production via the stimulating centers from TRH (thyroid releasing hormone) from the hypothalamus and then TSH from the pituitary, if a problem exists at the periphery the likelihood of getting an accurate assessment is diminished. A normal TSH reading is defined as 0.4-4.5 mU/L but generally many Doctors do not consider someone hypothyroid unless they present with a TSH over 4 mU/L.

Increasingly some Doctors are becoming aware of the reduction of hypothyroid symptoms when TSH is kept below 1mU/L and some evidence suggests that even at 0.5 mU/L (lowered but suppressed) is ideal to ensure that hypothyroid symptoms are decreased (Pantalone & Nasr, 2010).

Me? I am going to go back and contradict myself and say that numbers are useful. The basal temperature test with a cheap thermometer, as championed by Broda Barnes still suggests a good window of function of the thyroid test. 36.5 to 37 degrees is considered normal and reflects a well functioning metabolism. Couple that with a pulse rate test and you can also get a good indication of cortisol. So I am not against the numbers. I just think we need to ask better questions before we accept them as absolutes.

References:

Hoang, T. D., Olsen, C. H., Mai, V. Q., Clyde, P. W., & Shakir, M. K. M. (2013). Desiccated thyroid extract compared with levothyroxine in the treatment of hypothyroidism: A randomized, double-blind, crossover study. Journal of Clinical Endocrinology and Metabolism, 98(5), 1982–1990. http://doi.org/10.1210/jc.2012-4107

Illich, I. Limits to Medicine – Medical Nemesis. Marion Boyars. 1976.

Pantalone, K. M., & Nasr, C. (2010). Approach to a low tsh level: Patience is a virtue. Cleveland Clinic Journal of Medicine. http://doi.org/10.3949/ccjm.77a.10056