Thyrotoxicosis

THYROTOXICOSIS

Dr Mukhilesh R M.S.,

Hyperthyroidism

This disease result from an excess of circulating thyroid hormone.

Its very important to distinguish disorders:

1.Cause excess production of hormone - characterized by increasing in radioactive iodine uptake.

2.An other condition which release stored hormone such as thyroiditis.

Hyperthyroidism VS Thyrotoxicosis

Not all manifestations are related to elevated thyroid hormones.

Clinical types

Primary thyrotoxicosis – Grave’s Disease

Secondary Thyrotoxicosis – Plummer’s Disease

Toxic nodule Rare causes for hyperthyroidism

Grave’s Disease

Diffuse vascular goitre. Symptom appears with

goitre Younger women with

eye signs TSH-R Abs –

hypertrophy and hyperplasia of the thyroid tissue.

Toxic Nodular goitre

Long standing nodular goitre Middle aged women

infrequently associated with eye signs

Internodular tissue is the active region

Rarely , autonomous nodules.

Toxic nodule

Overactive nodule part of generalised nodularity or true toxic adenoma.

Not related to TSH-R Abs. Normal thyroid tissue is suppressed

and inactive.

Histology

SCALLOPED PATTERN

THYROXINE IS THE KEY FOR

ADRENALINE TO ACT ON THE CELL

Clinical Features

Primary VS Secondary Thyrotoxicosis

Features Primary Thyrotoxicosis

Secondary Thyrotoxicosis

Goitre Firm , diffuse and vascular / Bruit

Nodular

Hyperthyroidism

Severe Not severe

CVS Rare Most severe

Ophthalmic Features

More common Lid lag and spasm

Cardiovascular Symptoms

Secondary thyrotoxicosis

Multiple extrasystoles Paroxysmal atrial fibrillations Paroxysmal atrial tachycardia Paroxysmal atrial fibrillations.

Eye Signs

Primary thyroosicosis Lid spasm – sympathetic overactivity Exophthalmus Joffrey’s and VonGraffe’s sign Mobieus Sign Auto immune etiology – glycosamino

glycans deposition Weakness of extraoccular muscle Pappilloedema and corneal ulcers

Contd..

Malignant exophthtalmus – eyes may be destroyed.

Treatment of malignant exophthalmus

Rx Control of hyperthyroidism Sleeping propped up position Lateral tarsoraphy Prednisone Intraorbital steroid are to be avoided. Thryoid ablation with radio iodine

worsens the malignant exophthalmus Orbital decompression.

Thyroid dermopathy

Hyaluranic acid – dermis and subcutaneous tissue.

Rx – topical steroids

Diagnosis of thyrotoxicosis

Clinical features Biochemical investigation Thyroid antibodies

T3 T4 TSH

HYPERTHYROIDSM

INCREASED

INCREASED

SUPPRESSED

T3 TOXICOSIS INCREASED

NORMAL SUPPRESSED

Contd…

Thyroid scan Toxic nodular goitre

Principles of treatment of thyrotoxicosis

Anti thyroid durgs Carbimazole and propylthiouracil, Beta blockers – propranolol and nadolol Iodides – reduce vascularity,

preoperative scenario Cannot cure toxic nodule

Contd…

Dosage – 10 mg of carbimazole tds can be increased up to 120mg per day.

Levels of TSH R Ab fall and permanent cure in 50%

BLOCK AND REPLACEMENT REGIMEN

Inhibit all T3 and T4 with high dose of carbimazole and replace with thyroxine 0.1-0.15mg

Surgery

Helps in reducing the mass of overactive tissue.

Reduction of TSH R Abs or only limited stimulation.

Toxic nodule – suppressed tissue acts normal after the surgery.

Radio Iodine

Destroys thyroid cells. Functioning tissue reduced beyond

critical level. Accurate dosage is difficult and may

require further dose after 12 weeks. No evidence proven – therapeutic

dosage is carcinogenic.

Anti- thyroid drugs

• No surgery and radio iodine effects

• prolonged• 50% failure

rate• difficult to

predict response.

• agranulocytosis or aplastic anemia

Surgery

• Goitre is removed

• Cure is rapid • High cure rate

• Permanent thyroid failure

• Hypoparathyroidism

• Recurrence <5%

Radioiodine

• No prolonged drug therapy

• indefinite follow up

• slow response• Accurate

dosage - difficult

Choice Of Therapy

Factors influencing Type of thyrotoxicosis Age of the patient Co existing medical illness Post treatment care Follow up Compliance and Patient wishes.

Diffuse Toxic Goitre

Radio Iodine

Age >45

Large goitre – surgery

Small goitre – antithyroid drugs or radio iodine

Age<45

Toxic Nodular Goitre

Enlarges with antithyroid drugs.

Responds poorly with drugs and radio iodine

Surgical removal is the treatment.

Toxic Nodule

Surgery vs Radio Iodine.

Pros and cons to be considered.

Special situations

Pregnancy

Radio iodine – absolute C/ISurgery – abortionDrugs – hypothyroidism both mother abd babySurgery in second trimester or careful administration of drugs

Children

Radio iodine – C/I

Surgery - recurrence

Drugs till adoloscents

Surgery later.

Thyrocardiac

Severe cardiac damage

Radio iodine with anti thyroid drugs

Hyperthyroidism Due To Rare Causes

Thyrotoxicosis factitia

Jod-Basedow Thyrotoxicosis Large doses of iodine in endemic goitre

deQuervain’s thyroiditis

Carcinoma

Preoperative preparation Extent of resection

Biochemically euthyroid

Antithyroid drugs

Block and replacement regimen

Lugol’s iodine

Beta blockers

Surgical optionsFeatures

Control of toxicity

Return to euthyroid state

Recurrence

Thyroid failure

Hypoparathyroidism

Followup

Total Thyroidectomy

Immediate

Immediate

None

100%

5%

Minimal

Subtotal thyroidectomy

Immediate

Variable

5%

25%

1%

lifelong

Thyrotoxic Crisis

Thyroid storm

Acute exacerbation

Etiology Inadequately preapred Infection / stress

Clinical features Dehydration Hyperpyrexia Tacycardia Diaphoresis

Contd…

Rx

Intravenous fluids / rehydration

Cooling the patient with ice packs

Diuretics

Manage cardiac failure with digoxin

Hydrocortisone

Specific Rx

Carbiamzole – 10-20mg q6hrly

Lugol’s iodine 10drops q8hrly

Sodium iodide 1g i.v

Propranolol 1-2 mg i.v

Post Operative Follow Up

Hypocalcemia

Thyroid function test

Replacement of thyroxine