Thyroid Monitoring Advice
Tayside Version
 

NOTICE; This version is used by the Consultant Endocrinologists on Tayside and is specifically for local advice to their primary healthcare professionals and training of staff. Where official guidance is available this is followed. The reference values are those of Clinical Biochemistry, Ninewells Hospital , Dundee . Others should only use this in conjunction with local specialist opinion taking into account the variation in thyroid hormones measured and assay methods used which may alter the reference ranges. Such information must at all times be checked with a person’s health provider.  

  ON THYROXINE REPLACEMENT  

Check for specified conditions where a suppressed TSH value is maintained namely;

      ·        Thyroid cancer
·        Informed patient preference
Then make no adjustment to dosage unless clinically thought essential
NB; take advice from endocrine specialist if required  

NB. Hypopituitarism replaced with thyroxine often exhibit TSH <0.1mU/L and such is NOT an indication to reduce the thyroxine dosage – in such situations rely on FT4 (free Thyroxine) and TT3 (total tri-iodothyronine) maintained within the usual reference intervals. 

If there is NO specified reason for suppressed TSH (thyroid stimulating hormone) then;  

If on thyroxine 200mcg/day or more, reduce dosage by 50mcg/day
            Reassess in 3 months; clinical and TSH level

If on thyroxine 50 to 175mcg/day then reduce by 25mcg/day
            Reassess in 3 months; clinical and TSH level

            If on thyroxine 25mcg/day then cease thyroxine
            Reassess in 3 months; if then TSH still suppressed refer to Specialist Thyroid Clinic  

NOT ON THYROXINE

Refer to Specialist Thyroid Clinic  

NB hypopituitarism may have TSH<0.1 mU/L
            Refer to Specialist Hospital Clinic
 

ON THYROXINE REPLACEMENT

No adjustment advisedWith dysthyroid eye disease it is essential that TSH does not become elevated above normal reference range at any time and so our advice is to provide sufficient thyroxine to maintain the TSH at less than 2.0 mU/L, so providing a margin of safety.

NOT ON THYROXINE REPLACEMENT

            If TSH 0.1 to 0.3 mU/L
            This might be due to non-thyroidal illness so confirm low TSH after 2-3 months
            Refer to Specialist Hospital Clinic for assessment
            NB; take specialist advice if unsure for some clinical reason

            If TSH >0.3 to 3.9 mU/L
            Continue yearly monitoring  

Not on Thyroxine

            If TSH >=4.0 up to 9.9 mU/L
            There is some difference in specialist opinion in UK with some advocating replacement whereas others will not do so unless thyroid 
            antibodies are positive
            Tayside specialists advise replacement in all with TSH 6.0 mU/L or above and in those 4.0 to 5.9 mu/L where there are symptoms 
            of  hypothyroidism and/or thyroid antibodies.  

Begin thyroxine replacement
            Thyroxine 50mcg/day for 1 month
            (NB start at 25mcg/day in very elderly and cardiac disease)
            Then 75mcg/day
            Reassess at 3 months out from start of therapy; clinical and TSH level  

            If TSH 10.0 mU/L or greater
            Begin thyroxine 50mcg/day for 1 month
            (NB start at 25mcg/day in very elderly and cardiac disease)
            Then thyroxine 100mcg/day
            Reassess at 3 months out from start of therapy; clinical and TSH level  

On Thyroxine therapy  

Check for compliance with therapy.
            Suspicion of lack of compliance with therapy is suggested by;
            ·        Variable TSH values within  and outside reference ranges over years despite adequate replacement dosages
            ·        High dosages of thyroxine (i.e. >=150mcg/day) and yet have raised TSH values
            ·        High TSH level with high FT4 value
            ·        NB; take advice from specialist if required  

If compliance satisfactory
            Increase thyroxine dosage by 25mcg/day
            Reassess in 3 months; clinical and TSH level  

Thyroid Cancer

To prevent recurrence of the cancer TSH is maintained suppressed i.e. <0.03 or <0.1 mU/L by adequate thyroxine replacement. Follow up is complex requiring knowledge of thyroglobulin, anti-thyroid antibody level and clinical state and all such patients should be followed up by the Hospital Specialist Thyroid Service  

Informed Patient Preference

Some patients have made an informed decision to take a higher dosage of thyroid replacement than is required to maintain the TSH level within the reference range. This usually results in a TSH level of <0.1 or <0.03 mU/L. This is a risk especially in those with dysrythmias such as atrial fibrillation and those with osteoporosis. In such circumstances the informed patient’s decision is recorded and followed.

Dysthyroid Eye Disease

In those patients on thyroxine with dysthyroid eye disease it is essential that TSH does not become elevated above normal reference range at any time and so our advice is to provide sufficient thyroxine to maintain the TSH at less than 2.0 mU/L, so providing a margin of safety.

Pregnancy

Any woman on thyroxine replacement who becomes pregnant should increase their dosage by 25mcg/day immediately. Further adjustments may be required depending on monitoring TSH every 6-8 weeks during pregnancy.

Hypopituitarism

Hypopituitarism replaced with thyroxine often exhibit TSH <0.1mU/L and such is NOT an indication to reduce the thyroxine dosage – in such situations rely on FT4 and TT3 (FT3) maintaining these within the usual reference intervals

Ó NHS Tayside; 2006; version 1.0

Disclaimer; no liability whatsoever is accepted for information given and all such information, especially with regard to drug usage ( UK version provided), must be checked with a person’s health provider