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Hypothyroidism

HYPOTHYROIDISM

Definition:

Hypothyroidism is the clinical result of the impaired production of LT4 and LT3 which are essential for growth, development and metabolism.

 

When to refer:

·         Suspect uncommon cause for hypothyroidism (ie. medications- amiodarone)

·         Persistently raised TSH despite adequate treatment where reversible causes ( poor adherence, malabsorption, drug interactions) have been excluded

·         Persistent symptoms despite treatment ( following consideration of alternative causes of symptoms)

·         Suspect associated endocrine disease ie. Addisons

·         Pregnancy- if profoundly hypothyroid.

 

 

Red flags

If previously uninvestigated, unexplained palpable neck lump- REFER 2WW Head and Neck

 

Investigations prior to referral:

 

TSH/ T4

 

 

Primary care management:

 

Overt hypothyroidism – treat with levothyroxine

 

DO NOT PRESCRIBE COMBINATION THERAPY (LT4 and LT3) in primary care.

 

Aim to adjust dose to resolve symptoms and normalise TSH.

Once TSH stable, check levels  4-6monthly then annually.

If elderly remember to start at lower dose.

 

During pregnancy increase the patient’s normal dose by 25mcg and aim for a TSH below 2

 

 

 

 

 

Subclinical hypothyroidism

If TSH>10miu/L and fT4 in normal range:

 

If 70yrs or younger start treatment with LT4

If 70yrs+ consider watch and wait, if decide to treat with LT4, recheck TSH after 2months and adjust accordingly

 

If TSH 4-10miu/L and fT4 normal:

If <65yrs and symptomatic, consider trial LT4 assess response to treatment 3-4months after TSH in reference range.

If older (esp >80yrs), watch and wait

 

In asymptomatic patients, observe and repeat TFTs in 6months.

 

 References

 

Clinical knowledge summary-NICE : Hypothyroidism, April 2016         

Personal communication with Dr Duncan Browne, Consultant Endocrinologist, Treliske Hospital, November 2016