Relationship of thyroid dysfunction to Chronic Fatigue Syndrome

Editor’s Note: This article is reproduced with permission from InterAction magazine, the quarterly publication from the UK charity, Action for M.E. To find out more about support services provided by Action for M.E. to sufferers and their carers, please send email to or mail a self-addressed stamped envelope to Action for M.E., PO Box 1302,Wells, Somerset BA5 1YE, or telephone 01749 670799.


The purpose of this study was to evaluate the response to thyroid replacement therapy in patients considered to be suffering from underactive thyroid because of their presenting signs and symptoms, but whose thyroid biochemistry (i.e. blood test results) were within ‘normal’ laboratory reference ranges.

Presenting signs and symptoms of hypothyroidism include:

* Loss of energy, tiredness, lethargy or exhaustion

* Poor memory or concentration or ‘fuzzy head’

* Changes in skin (dry and flaky), hair (fine, coarse, thinning) or voice (deeper)

* Muscle or joint pain

* Constipation and/or bloated stomach

* Cold or heat intolerance

* Enlarged thyroid gland


Practice-based open interventions study; control group used for baseline laboratory values only.


The 139 patients studied who presented with the 16 recognised criteria of clinical hypothyroidism had been diagnosed with a range of different conditions: 64 with ME/CFS/PVFS, 32 with depression and 43 with other diagnoses, although these prior diagnoses are mentioned for interest only.

All patients were given 25mcg a day thyroxine sodium for the first week, building up by 25mcg at six week intervals until patient was clinically euthyroid (in optimum health’ with normal thyroid chemistry) Response to treatment was assessed on how many clinical signs and symptoms of hypothyroidism disappeared or improved (usually 6-12 months).


* In 22% of the patients all 16 clinical features of hypothyroidism either disappeared or improved.

* Patients FT4 (thyroid level) blood test results were averaging 13.2 prior to treatment but after treatment, when many signs and symptoms had improved, they were averaging 18.4.

* Likewise, TSH (thyroid stimulating hormone) blood test results were averaging 2.3 prior to treatment, but after treatment when many signs and symptoms had disappeared or improved, they were averaging 0.35. [the TSH has to work harder if there is less thyroid hormone available – Ed].

* Of the 139 patients studied, 129 (93%) had disappearance or improvement of at least 10 of the signs and symptoms. 93% of the study patients showed a remarkable improvement in their health, subjectively.


The study shows that the majority of patients, judged to be hypothyroid because of presenting signs and symptoms despite ‘normal’ blood test results, responded well to thyroid replacement therapy.

From the Journal of Nutritional and Environmental Medicine, as part of the study write-up:

‘In the absence of a control group, a placebo effect cannot be excluded in this or any other study. However, the average duration of illness was 7.5 years in patients who had usually undergone an alarming array of traditional and alternative medications without significant improvement as evidenced by their wish to seek further medical advice. Secondly, certain clinical features allowed objective assessment, namely changed in appearance, hair or skin texture, reduction in size of tongue and thyroid gland and increase in pulse rate. Therefore, while acknowledging the criticality of such a formal clinical trial – and indeed we are pleased to report that such a trial has been instituted at Stobhill Hospital, Glasgow – the proposition of placebo effect to explain sustained clinical response in 135 of 139 patients is unlikely.’

Dr Ellen Goudsmit comments:

‘This paper should be interpreted with care. The study does not relate specifically to CFS, but to people with chronic fatigue and symptoms of hypothyroidism. Some individuals with borderline values may be helped by thyroid supplementation but this should be supervised by an expert, with lots of experience.’

Clinical Response to Thyroxine Sodium in Clinically Hypothyroid but Biochemically Euthyroid Patients, Skinner G, Holmes D et al. Journal of Nutritional and Environmental Medicine. (2000) 10, 115-124

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