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)

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 Goiter 1.Simple (non-toxic ) Goiter a- Diffuse goitre b-Nodular goitre Either 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 until haemorrhage occurs, causing central necrosis and leaving only a 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 goiter Types of Toxic goiter: 1- Graves’ disease (primary toxic goiter ): a diffuse goiter associated with hyperthyroidism. Age group : usually occurs in younger women and is frequently associated with eye signs. 50% of patients have a family 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 21

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).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. 30