Trip Answers

Question answered:27/02/08

We found relatively little information to answer this question. However, the CKS guideline on hypothyroidism discusses the issue of feeling well and correlation with TSH level in the section on assessing response to levothyroxine treatment. It states:

 

“How should I assess response to levothyroxine treatment?
• Aim to make the person feel well, and achieve a serum thyroid-stimulating hormone (TSH) concentration that is within the reference range.
• If the TSH concentration is below the reference range, titrate the levothyroxine dose down in 25 microgram increments until TSH is within the reference range.
Clarification / Additional information
• Reducing the dose of levothyroxine may be difficult in some people who have an apparent psychological benefit and general feeling of well-being when their TSH concentration is undetectable. Titrating down by 25 micrograms in each instance may make this reduction possible.
• Some people will continue to feel unwell even when receiving adequate levothyroxine therapy and with their TSH and free thyroxine (FT4) concentrations within the reference range. It remains controversial whether this relates to their thyroid axis or coincident psychological morbidity. There is no trial evidence that increasing the levothyroxine dose will improve psychological or cognitive symptoms in these people.

 

Basis for recommendation
• These recommendations are from a UK consensus guideline produced by the Association for Clinical Biochemistry, British Thyroid Association, and the British Thyroid Foundation [BTA et al, 2006].
• A double-blind randomized crossover trial aimed to see whether well-being was optimized if the thyroid-stimulating hormone (TSH) concentration was kept within the lower part of the reference range in people with primary hypothyroidism (n = 56, including 52 women and 4 men) [Walsh et al, 2006]. Participants were given individualized levothyroxine doses. Assessment included the General Health Questionnaire, the Short Form-36, and the Thyroid Symptom Questionnaire.
o Levothyroxine dose adjustment with the aim of achieving serum TSH concentrations in the lower reference range (or slightly below) did not result in measurable symptomatic benefit compared with target TSH kept in the upper reference range.
o The authors concluded that the target TSH concentration in people with primary hypothyroidism should not differ from the normal reference range.
• Studies have shown that 21% to 59% of people receiving levothyroxine replacement therapy have TSH concentrations below the reference range…” [1]

 

Reference
1. CKS. Hypothyroidism. March 2007.
(http://www.cks.library.nhs.uk/hypothyroidism/in_depth/management_issues)

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