thyroid update
TRANSCRIPT
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