Thyroid Diseases

An UpdateBY

PROF/ GOUDA ELLABBAN

Aspects That Will Be Addressed

Hyperthyroidism Hypothyroidism Thyroiditis Iodine-induced

thyroid disease

http://perth.uwlax.edu/biology/faculty/maher/Jthryoid/img003.jpg

Thyroid Functions Cardiovascular…↑ B adrenergic

receptors GI…↑ peristalsis and vitamin A CNS…mentation and development MS…protein metabolism, growth and

maturation Respiratory…↑ surfactant synthesis CHO metabolism

Hyperthyroidism

Hyperthyroidism Symptoms Hyperactivity/ irritability/ dysphoria/

insomnia Heat intolerance and sweating Palpitations Fatigue and weakness Weight loss with increase of appetite Diarrhea Polyuria Oligomenorrhoea, loss of libido

Hyperthyroidism Signs Tachycardia (AF) Tremor Goiter Warm moist skin Proximal muscle

weakness Lid retraction or lag Gynecomastia Hair/nail changes

Causes of HyperthyroidismMost common causes

Graves disease Toxic multinodular

goiter Autonomously

functioning nodule

Rarer causes Thyroiditis or other

causes of destruction Thyrotoxicosis factitia Iodine excess (Jod-

Basedow phenomenon) Struma ovarii Secondary causes (TSH

or ßHCG)

Graves Disease Autoimmune disorder Abs directed against TSH receptor

with intrinsic activity. Thyroid and fibroblasts

Responsible for 60-80% of Thyrotoxicosis

More common in women

Graves’ Disease Autoimmune with over activity of thyroid

gland HLA-DR3 association Defect in suppressor T cells B cells synthesize thyroid-stimulating

immunoglobulin (TSI) Autoantibody against TSH receptor Gland becomes over stimulated and loses

negative feedback to T3 and T4

Graves’ continued… Associations:

Viral/bacterial infections Stress Exposure to iodide

Graves Disease Eye SignsN - no signs or symptomsO – only signs (lid retraction or

lag) no symptomsS – soft tissue involvement (peri-

orbital oedema)P – proptosis (>22 mm)(Hertl’s

test)E – extra ocular muscle

involvement (diplopia)C – corneal involvement

(keratitis)S – sight loss (compression of the

optic nerve)

http://www.muhealth.org/~daveg/thyroid/thy_dis.html

Graves’…Ophthalmopathy

Graves Disease Other Manifestations

Pretibial mixoedema Thyroid acropachy Onycholysis Thyroid enlargement

with a bruit frequently audible over the thyroid

Graves’…Dermopathy

http://www.ohiohealth.com/healthreference/reference/3C8F3995-E45A-406A-B785837268AEED7B.htm?category=questions

Diagnosis of Graves Disease TSH ↓, free T4 ↑ Thyroid auto

antibodies Nuclear thyroid

scintigraphy (I123, Te99)

Treatment of Graves Disease Reduce thyroid hormone production or

reduce the amount of thyroid tissue Antithyroid drugs: propyl-thiouracil (PTU),

carbimazole Radioiodine Subtotal thyroidectomy – relapse after

antithyroid therapy, pregnancy, young people? Symptomatic treatment

Propranolol

Considerations with Thionamides Both PTU and Methimazole may be

used in pregnancy PTU and Methimazole are considered

safe in breastfeeding Methimazole appears in higher

concentrations Watch for agranulocytosis

Fever Sore throat

Thionamides Cont… Measure FT4 and FTI every 2-4 weeks

and titrate accordingly Goal is high normal range 90% see improvement in 2-4 weeks

Iodine 131 Contraindicated in pregnancy Avoid pregnancy for 4 months after

131I treatment Avoid breastfeeding for 120 days

after 131I treatment Gestational age key when counseling

pregnant women exposed to 131I

Thyroid Storm Medical Emergency Occurs in ~ 1% of pregnant pts with

hyperthyroidism Diagnostic signs and symptoms:

Fever Tachycardia Altered mental status Vomiting and diarrhea Cardiac arrhythmia

More on Thyroid Storm If suspected, draw lab

FT4

FT3 TSH

Start treatment immediately

Toxic Adenomas Single Nodules Release excessive thyroid hormone Identified with radioactive scan “Hot Nodule”

Toxic Nodular Goiter

Develops from multinodular goiter Nodules become autonomous AKA Plummer’s disease

Factitious Hyperthyroidism Excessive intake/exposure to thyroid

hormone

Hypothyroidism

Hypothyroidism Symptoms Tiredness and

weakness Dry skin Feeling cold Hair loss Difficulty in

concentrating and poor memory

Constipation

Weight gain with poor appetite

Hoarse voice Menorrhagia, later

oligo and amenorrhoea

Paresthesias Impaired hearing

Hypothyroidism Signs Dry skin, cool extremities Puffy face, hands and feet Delayed tendon reflex

relaxation Carpal tunnel syndrome Bradycardia Diffuse alopecia Serous cavity effusions

Causes of Hypothyroidism Autoimmune

hypothyroidism (Hashimoto’s, atrophic thyroiditis)

Iatrogenic (I123treatment, thyroidectomy, external irradiation of the neck)

Drugs: iodine excess, lithium, antithyroid drugs, etc

Iodine deficiency Infiltrative disorders of

the thyroid: amyloidosis, sarcoidosis,haemochromatosis, scleroderma

Chronic ThyroiditisHashimoto’s

Autoimmune Initially goiter later very

little thyroid tissue Rarely associated with

pain Insidious onset and

progression Most common cause of

hypothyroidism TPO abs present (90 –

95%)

Hashimoto’s Thyroiditis MCC of hypothyroidism Autoimmune thyroiditis Women 30-50 years of age HLA-DR5 +

Antibodies in Hashimoto’s Antimicrosomal abys

Against peroxidase Antithyroglobulin abys

Against thyroglobulin Autoantibodies against TSH receptor

Net effect is prevent TSH stimulation of gland

Associations with Hashimoto’s Sjogren’s SLE Pernicious anemia

Risks with Immune Mediated Thyroid Dysfunction Antibodies cross placenta

In Graves’• TBII• TSI

In Graves’…1-5% of neonates have hyperthyroidism or neonatal Graves caused by maternal TSI

Incidence low due to balance of antibodies with thioamide treatment

Lab Investigations of Hypothyroidism

TSH ↑, free T4 ↓ Ultrasound of thyroid – little value Thyroid scintigraphy – little value Anti thyroid antibodies – anti-TPO S-CK ↑, s-Chol ↑, s-Trigliseride ↑ Normochromic or macrocytic anemia ECG: Bradycardia with small QRS

complexes

Treatment of Hypothyroidism Levothyroxine

If no residual thyroid function 1.5 μg/kg/day Patients under age 60, without cardiac disease

can be started on 50 – 100 μg/day. Dose adjusted according to TSH levels

In elderly especially those with CAD the starting dose should be much less (12.5 – 25 μg/day)

Table 1, ACOG Practice Bulletin Number 37, August 2002

TFT’s in Pregnancy and Disease

Maternal TSH FT4 FTI TT4 TT3 RT3U

PregnancyNo change

No change

No change ↑ ↑ ↓

Hyperthyroid ↓ ↑ ↑ ↑ ↑ or no change ↑

Hypothyroid ↑ ↓ ↓ ↓ ↓or no change ↓

Thyroiditis

Thyroiditis The most common form of thyroiditis

is Hashimoto thyroiditis, this is also the most common cause of long term hypothyroidism

The outcome of all other types of thyroiditis is good with eventual return to normal thyroid function

Thyroiditis Acute: rare and due to suppurative

infection of the thyroid Sub acute: also termed de

Quervains thyroiditis/ granulomatous thyroiditis – mostly viral origin

Chronic thyroiditis: mostly autoimmune (Hashimoto’s)

Acute Thyroiditis Bacterial – Staph, Strep Fungal – Aspergillus, Candida,

Histoplasma, Pneumocystis Radiation thyroiditis Amiodarone (acute/ sub acute)Painful thyroid, ESR usually elevated,

thyroid function normal

Sub Acute ThyroiditisViral (granulomatous) – Mumps,

coxsackie, influenza, adeno and echoviruses

Mostly affects middle aged women, Three phases, painful enlarged thyroid, usually complete resolution

Rx: NSAIDS and glucocorticoids if necessary

Sub Acute Thyroiditis (cont)Silent thyroiditis No tenderness of thyroidOccur mostly 3 – 6 months after

pregnancy3 phases: hyper⇒hypo⇒resolution, last

12 to 20 weeksESR normal, TPO Abs presentUsually no treatment necessary

Clinical Course of Sub Acute Thyroiditis

Chronic Thyroiditis

Reidel’s Rare Middle aged women Insidious painless Symptoms due to compression Dense fibrosis develop Usually no thyroid function impairment

Postpartum Thyroiditis May occur in 5% of women with no

known thyroid disease Clinically

44% hypothyroid 33% thyrotoxicosis 33% thyrotoxicosis followed by

hypothyroidism

Postpartum Thyroiditis Cont… Dx by abnormal TSH or FT4

Screen symptomatic women only Aby screening may be useful

Iodine-induced thyroid disease

Iodine Deficient Hypothyroidism Risk of congenital cretinism Treatment with iodine in 1st and 2nd

trimesters significantly reduces abnormalities of cretinism

www.emedicine.com/ped/topic501.htm

Cretinism

Summary Thyroid affects multiple organ systems Pathology may be infectious, autoimmune,

cancer, or combination Understand hormone levels change during

pregnancy Adequate treatment is the key to preventing

complications Recognize the many complications that may

occur in pregnancy and respond accordingly