Treatment of Hypothyroidism: A Reappraisal of Thyroxine Therapy

Evered, David; Young, E. T.; Ormston, B. J.; Menzies, Ruth; Smith, Pamela Alethea; Hall, R.

doi:10.1136/bmj.3.5872.131

Cited by 88 publications

(26 citation statements)

References 16 publications

(5 reference statements)

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“…Others have made similar recommendations, with 20-75% women increasing their dose in pregnancy, although the gestational ages at which testing or dose adjustment are made is not clearly specified. 5,6 Our data suggest strongly that women whose dose is being adjusted prior to conception or who are poorly compliant are more likely to need dose increases. This has not been reported previously, and possibly, together with other issues not related to the pregnancy may contribute to the apparently wide range of thyroid dose changes needed after conception.…”

Section: Discussionmentioning

confidence: 71%

Hypothyroidism in pregnancy: pre‐pregnancy thyroid status influences gestational thyroxine requirements

Kothari

Girling

2008

BJOG

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There is considerable uncertainty about the management of hypothyroidism in pregnancy. Our aim was to establish the pattern of thyroxine dose adjustment needed and to determine the clinical reasons for these changes and the contributory factors. Of 89 pregnancies, thyroxine dose was unchanged in 50, increased (by a mean of 38 micrograms) in 34, and decreased in 5. Twenty-three percent of women who were tested in the first trimester needed an immediate increase in thyroxine. One-quarter (26%) of the women who needed a gestational increase in thyroxine dose had had a recent pre-pregnancy increase in thyroxine requirement (compared with 0% in women on static dose in pregnancy, P < 0.001). Furthermore, they did not require a decrease in thyroxine dose postpartum, suggesting a long-term need for more thyroxine rather than a transient gestational effect. None of the women who had stable doses of thyroxine during pregnancy had required recent pre-pregnancy changes in dose or needed postnatal changes. Inadequate pre-pregnancy control of thyroid function is associated with a need to increase thyroxine dosage during pregnancy.

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Section: Discussionmentioning

confidence: 71%

Hypothyroidism in pregnancy: pre‐pregnancy thyroid status influences gestational thyroxine requirements

Kothari

Girling

2008

BJOG

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“…(7 Clin Endocrinol Metab 39: 923, 1974) C HRONIC therapy of patients with hypothyroidism with thyroxine (T 4 ) is known to result in dose related increases in serum T 4 levels and decreases in serum thyrotropin (TSH) levels (1)(2)(3). More recently the fact that serum triiodothyronine (T 3 ) levels also increase in such patients has been well documented (3)(4)(5)(6)(7). In these studies the precise relation of the time of hormone administration to the time at which measurements were made was not stated.…”

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confidence: 99%

Serum Thyroid Hormone and Thyrotropin Concentrations During Thyroxine and Triiodothyronine Therapy

Saberi

Utiger

1974

The Journal of Clinical Endocrinology & Metabolism

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Measurements of serum triiodothyronine (T 3 ), thyroxine (T 4 ) and thyrotropin (TSH) concentrations were made in hypothyroid patients at 2-hr intervals for 48 hr before and during chronic therapy with single daily doses of 25 and 50 fig T 3 or 100 and 200 ^g T 4 . No time-related changes were found in serum T 3 , T 4 or TSH levels during therapy with 100 or 200 fj.g T 4 daily. In patients treated with T 3 , prompt increases in serum T 3 levels occurred which reached a peak after 4 hr and then gradually returned to base line. Base line serum T 3 levels were, respectively, 101 ± 13 and 94 ± 9 ng/100 ml (SEM) and the peak levels were 223 ± 17 and 235 ± 18 ng/100 ml on the 2 study days in patients receiving 25 fig T 3 daily. Base line serum T 3 levels were 109 ± 18 and 116 ± 13 ng/ 100 ml and peak values were 350 ± 30 and 375 ± 31 in the patients receiving 50 fig T 3 daily. Serum TSH levels were elevated (mean basal serum TSH 13.1 ± 3.9 and 14.2 ± 4.7 /iU/ml) in the patients receiving 25 fxg T 3 daily and also elevated (mean basal serum TSH 11.8 ± 5.4 and 11.8 ± 6.0 /iU/ml) in the patients receiving 50 (xg T 3 daily. No changes in serum TSH were observed in the intervals between doses of T 3 in either group.These results indicate that once daily T 4 therapy is not associated with any acute changes in either serum T 4 , T 3 or TSH levels. While striking alterations in serum T 3 levels follow once daily T 3 therapy, these changes are not associated with any acute changes in serum TSH levels. (7 Clin Endocrinol Metab 39: 923, 1974)

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“…The use of a clinical index again proved to be of little value. 9 Altogether 79% of patients were clinically euthyroid at the time of survey and they were found to be clinically and biochemically similar irrespective of time since operation.…”

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confidence: 99%

“…The possible long-term significance of a minor reduction in serum T-4 and increase in serum TSH is not certain at present and will require further long-term studies. Medical3Journal, 1973, 3, 131. 10 Evered, D. C., et al, British Medical Journal, 1973, 1, 657. "Himsworth, R. L., and Fraser, P. M., British Medical3Journal, 1973, 3, 295.…”

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confidence: 99%

Comparative study between endoscopy and radiology in acute upper gastrointestinal haemorrhage.

Hoare¹

1975

BMJ

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these subjects had the highest T-4 and T-3 values recorded in the survey. The use of an established index6 was unhelpful in identifying these patients.The clinical features of hypothyroidism had been previously recognized in 12% of patients and the diagnosis confirmed, and a further four subjects were found to be clinically hypothyroid when recalled for study. This group had the four highest TSH values and lowest T-4 values in the survey. The T-3 values were also very low in three of these patients, the fourth value lying within the normal range. The use of a clinical index again proved to be of little value.9Altogether 79% of patients were clinically euthyroid at the time of survey and they were found to be clinically and biochemically similar irrespective of time since operation.Of this group 65% had a raised serum TSH. Our study of patients a year or more after subtotal thyroidectomy suggests that the serum TSH may remain consistently raised for many years. It is difficult, however, to be certain that there is no change in thyroid function over the years since patients who develop clinical thyroid failure, and who have the highest TSH values,'" are progressively removed from this followup group for treatment.The significance of a raised serum TSH in asymptomatic subjects has been the subject of much controversy.'0" It has now been established in a large-scale community survey that TSH values over 5 piU/ml are seen in less than 25 % of the normal population. Now that the normal range of serum TSH concentrations in normal subjects has been defined it may be assumed that any increase in serum TSH concentration reflects downward deviation from the optimum level of circulating thyroid hormones and to some extent gives an indication of the magnitude of that deviation. This contention is supported by our data. The mean serum T-4 in the euthyroid subjects with a normal TSH was very similar to that observed in a normal population. The serum T-4 in the group with a raised serum TSH was significantly lower but still within the normal range. The serum T-3 concentrations were similar in both groups. These findings confirm similar observations in radioiodine-treated patients." 15 Hence probably this minor reduction in total thyroid hormone concentration is sufficient to induce a rise in serum TSH but insufficient to produce the clinical features of thyroid failure. The maintenance of the serum T-3 level in patients with mild and subclinical thyroid failure has been reported previously'018 and was confirmed in our study. This presumably reflects a compensatory mechanism, probably TSH dependent, whereby smaller amounts of iodine are used to produce a metabolically more potent thyroid hormone. The finding of a normal or mildly raised T-3 in the face of a raised serum TSH shows that T-3 cannot be the sole regulator of pituitary TSH release.Subtotal thyroidectomy in this series rendered 79% of patients clinically euthyroid. The high prevalence of raised serum TSH levels in euthyroid subjects after thyroid surgery is confirmed a...

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Treatment of Hypothyroidism: A Reappraisal of Thyroxine Therapy

Cited by 88 publications

References 16 publications

Hypothyroidism in pregnancy: pre‐pregnancy thyroid status influences gestational thyroxine requirements

Hypothyroidism in pregnancy: pre‐pregnancy thyroid status influences gestational thyroxine requirements

Serum Thyroid Hormone and Thyrotropin Concentrations During Thyroxine and Triiodothyronine Therapy

Comparative study between endoscopy and radiology in acute upper gastrointestinal haemorrhage.

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