Hyperthyroidism.

Normal range.

  • FT4   10 - 22.
  • TSH   0.6 – 4.8.

1% of females.

Aetiology.

Primary.

  • 80%
  • Toxic multi-nodular goitre.
  • Toxic adenoma.
  • Ectopic – struma ovarii.
  • Thyroid cancer.

Secondary.

  • TSH secreting pitiutary tumour.
  • Hydatidiform mole (hCG has thyroxine like properties).
  • Thyroiditis – post partum, subacute deQuervains, amiodarone.
  • Thyroxine overload from treatment.

Graves most common under 50.

Toxic multi-nodular over 50.

Symptoms.

  • Fatigue
  • Weight loss.
  • Hunger
  • Diarrhoea
  • Palpitations
  • Heat intolerance.
  • Itch
  • Insomnia
  • Sweating
  • Anxiety
  • Oligomen
  • Depression (apathetic thyrotoxicosis of elderly).

Signs.

  • Goitre 90%.
  • Tremor
  • Hyper-reflexic.
  • Lid lag and retraction –not Graves specific.
  • Hair loss.
  • Muscle weakness ,proximal myopathy.
  • Tachycardia
  • Fib.
  • Osteoporosis on DEXA.

Diagnosis.

Biochemistry.

  • In primary, TSH is suppressed by NFL.
  • FT4 raised.
  • Beware of diagnosing on basis of low TSH as can be low in lots of ill patients.

Radiology.

Radiolabelled scan can tell if diffuse uptake (Graves), patchy (nodular) or less uptake (thyroiditis).

Note on Graves disease.

  • Auto-immune.
  • Produces TSH receptor stimulating antibodies.
  • May have other auto-immune condition.
  • TSH-like antibodies + gland.
  • Strong FHx.
  • Painless diffuse goitre.

Eye signs:

  • NO SPECS.
  • More prevalent in smokers.

Rarely pre-tibial myxoedema.

Treatment.

  • b-blockers.
  • Anti thyroid drugs. Graves less than 50.
  • Radiation All patients over 50.
  • Surgery

b-blockers.

  • Propranalol 20 to 40mgs TDS for symptom control.

Anti-thyroid drugs (thionamides).

  • carbimazole
  • propylthiouracil

These prevent Iodine incorporation.

Indications:

Graves in young. – 50% chance of remission.50% will recur.

To render someone Euythyroid pre surgery or I-131.

Of no use in thyroiditis.

Side effects:

Rash.

Agranulocytosis in 0.1%. Check FBC pre-treatment.Give advise re infections.

Propylthiouracil safer in pregnancy.

Use as:

  • Reducing from high to low dosage until euthyroid then maintain for 2 years.
  • “Block & replace regime” where get antithyroid drug at same dosage but thyroxine added after few weeks.Less frequent follow up needed and 6 months treatment needed.

Check effect by measuring FT4, TSH levels unhelpful as can remain suppressed for some time.

Advise of 50% recurrence rate.

 

 

Radiation.

  • Iodine-131.
  • Safe.
  • Use in all patients over 50.
  • Need pre-treatment with carbimazole – stop 1 week pre and start > 3 days after.
  • Can use for all types except thyroiditis.
  • Aim for hypothyroid state.
  • Avoid close contact with kids for few weeks.
  • Long term follow up.
  • 20% need repeat.

C/I:

  • Pregnant. Can conceive 4/12 after.
  • Breast feeding.
  • Children.

Surgery.

  • Rare.Only if treatment failure.
  • Make euthyroid pre treatment.
  • S/E:
  • Hypo PTH.
  • Rec. laryngeal nerve palsy.
  • Haemorrhage.

Sick euythyroid.

  • Low TSH but normal FT4.
  • This has increased incidence of A. Fib (x3) and osteoporosis.
  • Treat actively.