Management of Thyrotoxicosis

Ahmed Ali KhanFinal year MBBS2011-12 Batch

JSS Medical College, Mysore

Investigations

Thyroid Function Tests• Serum T3 or T4 levels are very high. TSH is very

low or undetectable. (Normal T3 – 3-9 pmol/L)

(Normal T4 – 8-26 pmol/L)

• If eye signs are present along with the above values, then other tests are generally not needed.

Radioisotope study• An 123I or 131I uptake and scan should be

performed. • An elevated uptake shows ‘hot areas or

nodules’.• Grave’s disease shows diffuse uniform over-

activity.• It also helps to differentiate it from other

causes of hyperthyroidism.

Antibodies• Anti-Tg and anti-TPO antibodies are elevated

in up to 75% of patients.• Elevated TSH-R or thyroid-stimulating

antibodies (TSAb) are diagnostic of Graves' disease and are increased in about 90% of patients

Other Investigations• ECG to look for cardiac involvement.

• TRH estimation.

• Total count and neutrophil count are very essential as anti-thyroid drugs may cause agranulocytosis.

Management

• Thyrotoxicosis may be treated by any of 3 treatment modalities —

1. Antithyroid drugs2. Surgery3. Radioiodine Therapy 131I

Anti Thyroid Drugs• Indicated in children, pregnant women and

young adults.

• Drugs help maintain euthyroid state for a long time in hope of spontaneous remission and prepare the patient for surgery.

Anti Thyroid Drugs• Carbimazole, Propyluracil, Methimazole etc

are some of the commonly used drugs.

• B adrenergic blockers – Ex : Propranolol

• In pregnant women – propylthiouracil is preferred

Anti Thyroid Drugs• Lugol’s Iodine (5% iodine + 10% potassium

iodide) – decreases the vascularity of the gland only used as immediate preoperative measure. 10-30 drops/day for 10 days(makes the thyroid firm and easier to handle during surgery)

• Others – Lithium carbonate, Reserpine, potassium perchlorate

Anti Thyroid Drugs• Pros : no surgery and no use of radioactive• Cons: prolonged t/t and failure rate about

50%. • May also cause aplastic anemia,

agranulocytosis, hair loss and liver damage.• Poor prognosis : large gland size, severity of

disease nad TSH-Rab levels.

Surgical Treatment• Indications1. Failure of drug therapy2. Toxic nodular goitre3. Autonomous toxic nodule4. Suspected malignancy5. Grave’s disease in children6. Very large goitre(substernal/intrathoracic)

Surgical Treatment• Subtotal thyroidectomy – both lobes with

isthmus are removed and tissue equivalent to pulp of finger is retained at the lower pole of both the lobes.(5-8 grams)

• Hemithyroidectomy – done for autonomous nodule. Here, entire lateral lobe with the isthmus is removed.

• Total Thyroidectomy – Preferred in Grave’s disease to achieve lowest relapse rate.

Surgical Treatment• Pros – Rapid cure and high cure rate, problems

associated with radioiodine therapy can be avoided.• Surgery also provides tissue for biopsy.• Coexisting parathyroid Ca can be removed if present.• Only choice for very large retrosternal toxic thyroid.• Cons – Recurrence in 5% cases, Thyroid insufficiency

in (20-45%) and the generally encountered complications of surgery itself.

Radioactive Iodine Therapy (131I)

• Destroys thyroid cells and reduces mass of thyroid tissue below a critical level by ablation.

• Indications 1. Primary Thyrotoxicosis after 45 years2. Autonomous toxic nodule3. Recurrent Thyrotoxicosis

Radioactive Iodine Therapy (131I)

• Usual dosage is 160 microcurie/gm of thyroid• Patient is first made euthyroid by anti-thyroid

drugs. Then discontinued for 5 days after which oral radioiodine therapy is initiated.

• Once the preferred dosage is achieved, radioiodine therapy is stopped. Then anti-thyroid drugs are started after 7 days and continued for 8 weeks.

Radioactive Iodine Therapy (131I)

• It normally takes about 3 months to get full response. Additional 1-2 doses of radioiodine may be required.

• Due to the pre and post radioiodine therapy dosage of anti-thyroid drugs the patient may go into a state of hypothyroidism. This can be tackled by a maintenance dose of L-thyroixine 0.1mg daily.

Radioactive Iodine Therapy (131I)

• Pros – No Surgery, No prolonged drug therapy and a cure rate of about 90%

• Cons – Availabilty of services, necessity of proper regular follow up and more importantly, it may cause genetic mutation in younger individuals and thereby predisposing them to various malignancies. Hence, only useful in older adults(>45years).

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