Goiter

Dr. Gehan Mohamed

Thyroid enlargement

• The term goiter (from the Latin guttur = the throat) is used to describe generalised enlargement of the thyroid gland.

NORMAL SIZED THYROID

(black lining)ENLARGED GOITER

(pink)

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Causes of Goiter

GOITER

A goitre may be associated with:

• Normal thyroid hormonal activity (euthyroidism).

• Increased thyroid hormonal activity (hyperthyroidism).

• Decreased or absent thyroid hormonal activity (hypothyroidism).

Classification of Goiter1. Simple (non-toxic ) Goiter a-

Diffuse goitre b-Nodular goitreEither diffuse or nodular goiter can be sporadic

or endemic when more than 10% of any community have goiter

.

2. Toxic Goitre a- Diffuse toxic goiter(Grave’s Disease) b- nodularToxic goiter

Endemic goiter

T3

Hypothalamus

Anterior pituitary

Thyroid

TRH

TSH

T4

Remember this?

Iodide

io

Simple Goiter

Definition :it is goiter with normal thyroid hormonal functions.

Age group: May occur in any age group-from neonate (congenital goiter) to the elderly. Peak age:31 and 40 years. The goiter appears in childhood in endemic areas but, in sporadic cases, it usually occurs at puberty when metabolic demands are high.

Aetiology of goiter• A- deficiency of the thyroid hormones lead to Increased secretion

of TSH which stimulate thyroid to grow:

causes of thyroxine deficiency are:

1. Inadequate iodine in diet

2. Impaired absorption of iodine from the gut

3. Drugs preventing trapping and concentrating of iodine by the thyroid gland

4. Dyshormonogenesis: deficiency of enzymes necessary for oxidising iodine, coupling of iodine and tyrosine

5. Excessive iodine paradoxically interfering with release of hormones from the thyroid.

6. Goitrogens: Well-known goitrogens as cabbage,cauliflower,turnip which contain thiocyanate which prevent thyroxine hormone production.

Aetiology of goiter

B- inappropriate secretion of TSH from a microadenoma in the anterior pituitary

C- Relative Physiological Deficiency:

Physiological states such as puberty ,menstruation, pregnancy and lactation there is Increase demand for thyroid hormones due to increase in metabolic activity

Mechanism of enlargment of thyroid in case of Simple Goiter:

The stages in goiter formation are as follows:•1- decrease level of thyroxine hormone secretion stimulate release of excess

TSH which cause growth stimulation and diffuse hyperplasia of the thyroid gland ; all lobules are composed of active follicles and iodine uptake is uniform.

This is a diffuse hyperplastic goiter, which may persist for a long time but is reversible if stimulation ceases.

• 2- Later, as a result of fluctuating stimulation of the thyroid (alternating hyperplasia and involution of the thyroid ), a mixed pattern develops with areas of active lobules and areas of inactive lobules.

• Active lobules become more vascular and hyperplastic untilhaemorrhage occurs, causing central necrosis and leaving onlya surrounding rind of active follicles.• Necrotic lobules coalesce to form nodules filled with either iodine-free colloid

or a mass of new but inactive follicles.• Continual repetition of this process results in a nodular goitre. Most nodules

are inactive, and active follicles are present only in the inter nodular tissue

Diagnosis of simple goiter

Symptom: swelling in the neck-a major complaint .Pressure symptoms like difficulty in swallowing and breathing .

Examination findings on Nodular Goitre

• A visible goiter that moves up and down on swallowing

• May be small, moderate, large or giant in size and affects one of the two lateral lobes or the isthmus or all the lobes.

• Skin over goiter is often shiny with engorged superficial veins .

Investigations

• Imaging: x-ray of the neck including thoracic inlet,, ultrasound, CT scan

• Thyroid function test

• Direct and indirect laryngoscopy

COMPLICATIONS OF simple GOITER

• Pressure symptoms-dyspnea, dysphagia

• Toxicity-secondary thyrotoxicosis may occur

• Malignant change

• Infection

ectomy

Management of simple goitre

Prevention• Iodine supplementation in food

Drug Therapy• Iodine therapy-Lugol’s iodine or potassium iodide tablets-early

cases of endemic and sporadic goitres especially adolescent hyper plastic goitre

• Thyroxine and its analogues-diffuse hyperplastic goitre.

Surgery :thyroidectomy for simple nodular goitre

Indicated for the following reasons:• An increasing growing thyroid• Trachea compression• May become toxic• Malignancy may occur

2- Toxic goiterTypes of Toxic goiter: 1- Graves’ disease (primary toxic goiter ): a diffuse goiter associated with hyperthyroidism.

Age group : usually occurs in younger womenand is frequently associated with eye signs. 50% of patients have afamily history of autoimmune endocrine diseases.

-Mechanism : Graves disease is an autoimmune disease that cause hypertrophy and hyperplasia of the thyroid due to abnormal thyroid-stimulating antibodies (TSH-RAbs) that bind to TSH receptor sites and produce a disproportionate and prolonged effect.-Triad of Graves disease: 1- hyperthyroidism 2- exophthalmos due to deposition of proteoglycans ,edema,lymphocytic infiltrate. 3 – dermopathy in form of pretibial myxedema

Toxic goiter

2- Toxic nodular goiter (secondary thyrotoxicosis): A simple nodular goiter is present for a long time before the hyperthyroidism, usually in the middle-aged or elderly, and is very infrequently associated with eye signs.

Diagnosis of toxic goiter

A- manifestations due to enlargment of the thyroid

•Swollen front of the neck

•A tight feeling in the throat

•Coughing

•Difficulty in swallowing & breathing

B- manifestations of THYROTOXICOSIS

• Symptoms:– Hyperactivity– Irritability– Heat intolerance &

sweating– Palpitations– Fatigue & weakness– Weight loss with

increased appetite– Diarrhea– Polyuria– Sexual dysfunction

• Signs:– Tachycardia– Atrial fibrillation– Tremor– Goiter– Warm, moist skin– Muscle weakness,

myopathy– Lid retraction or lag– Gynecomastia– * Exophtalmus– * Pretibial myxedema

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Exophthalmos associating Graves’ disease

Exophthalmos associating toxic goiter

Graves’ disease :Diffusely enlarged gland , Can weigh up to 200 g ,Richly vascular

Normal Thyroid

colloid

Thyroid epithelial cells

T4 90%

T3 10%

TSH

Toxic goiter

Toxic goiter:scalloping of colloid inside thyroid follicles

small sized follicles , lymphocytic infiltration,hypervascularity

Thyrotoxicosis - differential

• Graves’disease• Toxic adenoma (solitary)• Toxic multinodular goiter• Subacute thyroiditis• Hashimoto’s thyroiditis (transient hyperthyroid phase)• Thyrotoxicosis factitia(exogenous intake of excess synthetic thyroxine)• Postpartum• Struma ovarii(ovarian tumor contain thyroid tissue secreting thyroxine)• Metastatic thyroid carcinoma• Hydatidaform mole (mass or growth that forms inside the uterus at the

beginning of a pregnancy. It is a type of gestational trophoblastic disease ,thyrotoxicosis occur due to the extremely high levels of hCG, which can mimic the normal Thyroid-stimulating hormone).

• TSH-secreting pituitary tumor• Pituitary resistance to triiodothryonine and thyroxine

Other clinical presentations for patients with goiter

• As we previously mentioned patients with goiter may be :

1- euthyroid : normal thyroid functions

2- hyperthyroidism :toxic goiter

3- hypothyroidism: decrease thyroid functions ,

- hypothyroidism In infants called cretinism

- hypothyroidism In adults called myxedema

HYPOTHYROIDISM

• Symptoms:– Tiredness– Weakness– Dry skin – Sexual dysfunction

– Hair loss– Difficulty

concentrating

• Signs:– Bradycardia– Dry coarse skin– Puffy face, hands and

feet– Diffuse alopecia– Peripheral edema– Delayed tendon reflex

relaxation– Carpal tunel syndrome– Serous cavity effusions.

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