• Thyroid statistics
• Thyroid gland-Basics
• Synthesis of thyroid hormones
• How it functions
• Negative feedback system
• When to suspect thyroid disease
• Diseases affecting thyroid gland
• Thyroid function tests-Indications, TSH,TRH,T4,T3 etc.
• Thyroid examination
• Thyroid Scan-RAIU test
• CT Scan, PET Scan
• FNAC thyroid
• Diet in thyroid
• Thyroid and pregnancy
• Thyroid and peadiatrics
• DM and thyroid disorders
• Thyroid and HTN
• Thyroid and dermatology
• Thyroid and dyslipedemia
• Thyroid and infertility
• Thyroid –Comorbidities and complications
• Thyroid and Covid -19
• 42 millions people in India have thyroid disorders.
• 2nd most common endocrine disorder in India
• Subclinical hypothyroidism is 11%.
• Hyperthyroidism present in <2%
• About 12% adults have a palpable goitre.
• 1/10 adults have hypothyroidism (only 2% in the UK and 4-6% in
• Among cancers, thyroid cancer 0.1-0.2 %
• Congenital hypothyroidism occurring in 1 out of 2640 neonates
(India ) and the worldwide average value of 1 in 3800 subjects.
• Second largest endocrine gland.
• Small butterfly shaped gland located at the base of neck.
• Controlled by the hypothalamus and pituitary.
• Triodothyronine T3
• Tetraiodothyronine/Throxine T4
(produced by follicles)
• T4 kidney, liver, spleen T3
• T3 is 10x more active than T4
• Thyrothrophin (TSH) is a pituitary hormone.
• Controlled by TRH- thyrotrophin releasing hormone from
Produced by thyroid (parafollicular cells) to regulate serum
Steps in thyroid synthesis
TRH release from hypothalamus Ant Pituitary
to release TSH TSH stimulates follicular cells to
synthesis TGB(Thyroglobulin) Iodine trapping
Oxidation of Iodide (TPO ) Iodination of
Tyrosine amminoacid Coupling of DIT’s and MIT’s
Endocytosis of TGB with T3 and T4
Lysosomal enzymes cleaves T3 &T4 out of Thyroglobulin
Exocytosis T4 &T3 blood plasma
Thyroid Function Tests
• Blood tests
Serum TSH (Ultrasensitive assay)
Serum total T3
Serum total T4
Serum free T4 (or T3)
• Thyroid scanning – USG, Radioactive Iodine/Tc
• CT scanning
• PET scanning
INDICATIONS OF TFT
• To evaluate integrity of hypothalamic-pituitary-thyroid
• Diagnosing thyroid disorder in symptomatic person.
• Screening newborns for hypothyroidism.
• Monitoring thyroid replacement therapy in
• Diagnosis & monitoring female infertility patients.
• Screening adults for thyroid disorders
MEASUREMENT NORMAL RANGE
Total T4 (TT4) Bound & Free T4 5.0-11.0 ug/dL
Free T4 (FT4) Free T4 0.9-1.7 ng/dL
Total T3 (TT3) Bound & Free T3 100-200 ng/dL
T3 Resin Uptake Binding capacity of TBG 22-34%
TSH Thyroid stimulating
• First line test in Thyroid function tests
• Screening in euthyroidism.
• Screening of hypothyroidism in newborns.
• Diagnosis of 1 & 2 hypothyroidism.
• Diagnosis of clinical and subclinical hypothyroidism.
• Follow up of T3 & T4 replacement therapy in
• Best way to initially test thyroid function.
• Changes in TSH – “early warning system”
• Symptomatic 1⁰ hypothyroidism- >20mu/L
• Mild symptomatic 1⁰ hypothyroidism : 10-20 mu/L
• 1⁰ hyperthyroidism :<0.05 mu/L
• In 2⁰hypothyroidism low TSH levels, prevent making enough TSH to
• Regulates TSH secretion from pituitary.
• TSH rise of 5microunits/ml over baseline- euthyroid state
• Significant increase rule out hyperthyroidism.
Difference between T3 and T4
Secretion 30 microgram/day 80 microgram /day
Source 20-25% by gland
75-80% by conversion
Solely by gland
Half life 1 day 7 days
Potency 10 times more potent
Binding 0.2% in unbound 0.02% in unbound
Thyroxine binding globulin
Thyroxine binding free albumin
• Total T4 measure bound and free hormones-change when binding proteins
• Free T4(FT4) or free T4index (FT4I) –more accurately reflect hypothyroidism
• Elevated TSH and low FT4 or FTI → 1⁰ hypothyroidism
• Low TSH and low FT4 or FTI → 2 ⁰ hypothyroidism
• Low TSH with an elevated FT4 or FTI is found in individuals who
• Increased total serum T4 →hyperthyroidism or increased con of thyroid
• Decreased total serum T4 →hypothyroidism or decreased con of thyroid
binding proteins/ non thyroid diseases.
Free T4 index
• Total Serum T4(mg/dl) x T3 resin uptake(%)
• High in hyperthyroidism
• Low in hypothyroidism.
• T3 tests –diagnosis/ determine the severity of hyperthyroidism.
• In some individuals -low TSH, only T3 is elevated and FT4 or FTI
• T3 testing-rarely helpful in hypothyroidism, since it is last test
to become abnormal.
• Measurement of free T3 is possible, but is often not reliable - not
• Reverse T3 -biologically inactive- not clinically useful
• Total T3 –used to detect T3 toxicosis (increase T3 &normal T4)
Serum T3 resin uptake
• Thyroid hormone binding ratio
• The T3 resin uptake is high when thyroid binding protein is low
• Increase in T3 resin uptake – consistent with hyperthyroidism
• Decrease in T3 resin uptake – consistent with hypothyroidism
THYROID ANTIBODY TESTS
• A thyroid antibodies test is used to help diagnose autoimmune
disorders of the thyroid.
• + ve Anti-thyroid peroxidase (TPO) and / or Anti-thyroglobulin
antibodies(Tg) - Hypothyroidism - Hashimoto’s thyroiditis.
• Stimulatory TSH receptor antibody (TSI).
• Thyrotropin receptor antibody test (TSHR or TRAb), which detects
both stimulating and blocking antibodies
• TPO antibody: Serum level should be less than 9 IU/mL.
• Anti-Tg antibody: Serum level should be less than 4 IU/mL.
• Thyroid-stimulating immunoglobulin antibody (TSI):
This value should be less than 1.75 IU/L.
• Hypothyrodism – Under activity
Affect 5-17 % of population
Females > Males
Higher in >60 years old
• Types –Primary, Secondary,Teritary
Normally thyroid gland is not palpable .
• Examination is best carried out from behind, with neck
• Ask pt to slightly flex their neck.
• Assess * size
1.Place the 3 middle fingers of each hand along the midline of the neck below the chin
2.Locate the upper edge of the thyroid cartilage(Adam’s apple).
3.Move inferiorly until you reach the cricoid cartilage/ring
4.The first two rings of the trachea are located below the cricoid cartilage and the thyroid
isthmus overlies this area.
5.Palpate the thyroid isthmus using the pads of your fingers(index fingers)
6.Palpate each lateral lobe of the thyroid including inferior border in turn by moving your
fingers down and slightly laterally from the isthmus.
7.Ask the patient to swallow some water , whilst you feel for symmetrical elevation
/superior movement of the thyroid lobes.
8.Ask the patient to protrude their tongue once more.
If mass note- Assess –position,shape,tenderness,consisteny,mobility
• Information regarding size, shape, position of gland
• Functional classification of nodules
• To differentiate various causes of thyrotoxicosis.
• In ectopic or metastatic sites.
• Distinguishes diffuse glandular activity from patchy pattern
seen in goitre.
• In association with thyroid suppression regimes, TSH
dependent or autonomous nature of hot nodules.
• Thyroid nodules
• Diffuse or multinodular goitre
• Clinical hypo-or hyperthyroidism
• Evaluation of substernal mass
• R/O Ectopic thyroid issue
• Subacute thyroiditis, early phase
• Patient with previous h/o of H&N
Radioactive iodine uptake (RAIU) test
• RAIU test with thyroid scan.
• A radioactive material called a radioisotope, or radionuclide
“tracer,” is given before the test through an injection, a
liquid, or a tablet tracer releases gamma rays
when it’s in your body A gamma camera or
scanner can detect this type of energy from outside your body
The camera scans your thyroid area
Process images and interpet
• The CT scan is an x-ray test that makes detailed cross-sectional
• It can help determine the location and size of thyroid cancers
and whether they have spread to nearby areas
• Preoperative planning in patients with symptomatic goitre.
• Fluorine-18-fluorodeoxyglucose (FDG) Positron Emission
• Used to detect local recurrence and distant metastases
of thyroid carcinoma, especially in those patients who present
with high serum Tg, but negative I-131.
• Diagnosis of diffuse non toxic goitre, solitary or dominant thyroid
• Thyroid nodule over 1 cm in diameter.
• Confirmation of clinically obvious malignancy.
• For defining prognostic parameters.
• Inability to distinguish between follicular adenoma and carcinoma
• Local hemorrhage and hematoma.
• Transient laryngeal nerve paresis.
• Tracheal puncture.
• Rarely, needling causes formation of a hot nodule.
• Syringes and syringe holder
• 22-25 gauge needle
• Cotton swabs
• Alcohol bottles for wet fixation.
• Nodule size > 2cm diameter.
• Regional adenopathy.
• To find cause of nodule/goitre.
• Presence of distant metastases.
• Prior head or neck irradiation.
• Rapidly growing lesion.
• Development of hoarseness, progressive dysphagia, or
shortness of breath.
• Family history of papillary thyroid cancer.
• Alcohol even red wine
• Soy foods
• Carbonated drinks
• Fast foods
• Horse raddish
• Sweet potatoes
• Maple syrup
• Dried fruits
• White bread
• White rice
• White pasta
• Cafffeinated energy
Thyroid and pregnanacy
Hyperthyroidism- 2 per 1000 pregnancies
• first time Dx in pregnancy
• Hypothyroid women either discontinue thyroid therapy or
who need larger doses.
• Hyperthyroid women on excessive amount of antithyroid
• T3 &T4 can cross placenta, TSH not
• Thyroid stimulating antibodies in maternal
Cross placenta Produce neonatal thyrotoxicosis with
increased neonatal death.
• Gestational transient thyrotoxicosis (1st trimester)
High hCG levels TSH receptor stimulation and
• 20 week gestation
-Reduced hepatic clearance
- Estrogen –induced change in the structure of TBG that prolongs
serum half-life Plasma TBG increases 2.5 fold
25-45% increase in serum total T4
- Total T3 icreases by about 30% in 1st trimester and by 50% to 65
PEADIATRICS AND THYROID
Thyroid hormones growth, development, maturation
and brain functions are unique to pediatric age group.
Congenital and acquired disorders of thyroid gland -
constituting nearly 25-30% of all endocrinopathies.
The three major clinical forms of thyroid disorders are
1.Primary hypothyroidism (75%)
2.Goiters ( thyromegaly)- of which nearly 20%, no
alterations in thyroid function.
3.Hyperthyroidism or thyrotoxicosis in 5%
DM and Thyroid disorders
• Both are disorders of endocrine system.
• Thyroid plays imp role glucose metabolism –Glycogenolysis
and gluconeogeneis, insulin secretion
• Hyperthyroidism Hyperglycemia
• Hypothyroidism Hypoglycemia ,
also increase susceptibility to hypoglycemia thus complicating
• Hypothyroidism cause insulin resistance further can also leads
to hypergycemia ie Type II Diabetes mellitus
Thyroid and HTN
elevated T3 & T4 can cause 1. ↑ HR
2.↑ NE, E receptor sensitivity
Increase contractibility, vasoconstriction
Low T3 & T4 Acts on kidney causes Sodium retention
Na retention ↑ses Blood volume ↑ses
Increased BP ,T3 &T4 also increases diastolic BP.
THYROID AND DERMATOLOGY
• Resembles ichthyosis vulgaris
• skin cold and pale
• first clinical manifestation
• Broad nose, thick lips, upper lid droop, face expressionless.
• May have melasma like pigmentation.
• Dry,coarse, brittle hair
• Alopecia –patchy or diffuse ( first symptom of hypothyroidsm)
• Supraciliary madarosis typical
THYROID AND INFERTILITY
• Prevalence of hypothyroidism in women in reproductive age is 2%
• Males –rare -0.1%
• Increased TSH ↑ses prolactin
↑ses FSH ,LH ↓ses estrogen, Testosterone
Males - ↓ ses sperm production, Sexual drive ↓ ses , Libido
Females- Decreased ovulation, anovulation, menstrual abnormalities
High T3 & T4 act on liver produce TBG
Binds with T4 produce other globulin SHBG
Binds estrogen & Testosterone ↓es circulating estrogen and
testosterone in blood
Males - ↓ses sperm production, low libido, ↓ ses masculinisation
Females-Anovulation, Amenorrhea, Oligmenrhea
THYROID AND COVID -19
• There is no association b/w novel corona virus and
thyroid abnormalities so far.
• Vaccination do not interfere with thyroid medications.
A 50 year old housewife complains of progressive weight gain of 20
pounds ( 9 kg) in 1 year, fatigue, slight memory loss, slow speech, dry
skin, constipation, and cold intolerance
Physical examination : moderately obese, speaks slowly, puffy face,
with pale, cool, dry, and thick skin. The thyroid gland is slightly
enlarged, firm, not nodular, mobile, and not tender. The deep tendon
reflex time is delayed.
Laboratory studies: CBC and differential WBC are normal.
Serum T4 - 3.8 ug/dl, serum TSH is 23.0 uU/ml
Diagnosis : Primary hypothyroidism
:A 35 year old nurse complained of nervousness, mood swings,
weakness, and palpitations with exertion for the past 6 months.
Recently, she noticed excessive sweating and wanted to sleep with
fewer blankets than her husband. Menstrual periods had been regular
but there was less bleeding.
• Physical examination: Pulse -92/minute and BP -130/60. She
appeared anxious, with a smooth, warm, and moist skin, a fine
tremor, she couldn't rise from a deep knee bend without aid
• Laboratory studies: Serum T4=15.6 ug/dl and serum T3=185 ng/dl.
• Diagnosis : Primary Hyperthyroidism
• American thyroid association guidelines
• European thyroid association guidelines
• Thyroid disorders, Kottakkal Ayurveda Series 167.
• Davidson’s principles &practice of medicine-22nd edition
• Illustrated synopsis of Dermatology and sexually transmitted
diseases,Neena Khanna-6th Edition; page no 399
• Desai PM. Disorders of the Thyroid Gland in India. Indian J Pediatr
• Principles of Anatomy and Physiology –Gerald J Tortora-12th edition
• IAP Textbook of peadiatrics-7th edition
• Usha Menon V, Sundaram KR, Unnikrishnan AG, Jayakumar RV, Nair
V, Kumar H. High prevalence of undetected thyroid disorders in an
iodine sufficient adult south Indian population. J Indian Med Assoc
2-next to DM,if asymptomatic goitre is also included throid disease rank as most common
Subclinical hypothyrodism means normal T3&T4 with elevated TSH.. Among adult people in India, the prevalence of hypothyroidism has been recently studied. In this population-based study done in Cochin on 971 adult subjects, the prevalence of hypothyroidism was 3.9%. The prevalence of subclinical hypothyroidism was also high in this study, the value being 9.4%. In women, the prevalence was higher, at 11.4%, when compared with men, in whom the prevalence was 6.2%. The prevalence of subclinical hypothyroidism increased with age. About 53% of subjects with subclinical hypothyroidism were positive for anti-TPO antibodies.
congenital hypothyroidism is probably the most important- it is requires an early diagnosis- appropriate therapy that can prevent the onset of brain damage.
Interrelation b/w thyroid and diabetes
Located infront of neck, just below thyroid cartilage known as Adam’s apple.Anterior to trachea and just inferior to larynx.TG –bilobed structure(lobe either side of windpipe), endodermal orgin, 15-25g, Isthmus and 2 lobes.
Develops early as 3rd or 4th week of gestation, Foetal synthesis start by 11th or 12th week, untill depend on maternal thyroxine
Anabolic hormones, name mainly by iodine atom no, follicles are the functional unit of thyroid gland .Both contain iodine atom.Only 20% of total T3 secreted by thyroid, majority from catalysis of T4 by 5’-iodothyrorine deiodinase (highest activity in liver and kidney)-Selenium.T3 –active –bcoz it is not as tightly, T3 has greater affinity to target tissue recepor
T3 – Thyroid gland + peripheral deiodination of T4
TSH ,a glycoprotein-thyrotroph cells of anterior pituitary in response to hypothalamic tripeptide,TRH.
TSH Functions to stimulate thyroid hormone production.Calcitonin stimulates movement of calcium into bone.
1. iodide trapping, (2) oxidation of iodide and iodination of tyrosine residues, (3) hormone storage in the colloid of the thyroid gland as part of the large thyroglobulin molecule, (4) proteolysis and release of hormones, and (5) conversion of less active prohormone thyroxine to more potent ...
T4 &T3 inhibit TRH (from hypothalamus) and TSH (pituitary gland). So when T4 &T3 are less (as in hypohyrodism) TSH is increased in serum
Serum T3 resin uptake, freeT4 index
Normal TSH level excludes thyroid dysfunction. The most important screening test for thyroid diseases is TSH
TRH tests the ability of TRH to stimulate the pituitary to secrete TSH.
Is performed by drawing baseline serum TSH con and then administer ꭓ 200-400microgram of TRH by iv over30-60 secods.The TSH con drawn at 30-60 minutes.
Free T4 &T3 physiologically active portion,
T4 main form of thyroid hormone circulating in blood,3-due to disease in the thyroid gland, 4-due to a problem involving the pituitary gland.7-DM, liver disease,renal failure etc..
FreeT4 –measures unbound fraction of T4
Patients who are hyperthyroid will have an elevated T3 level, 3-Patients can be severely hypothyroid with a high TSH and low FT4 or FTI, but have a normal T3.
Reverse is structurally very similar to T3, but the iodine atoms are placed in different locations, which makes it inactive. . Some reverse T3 is produced normally in the body, but is then rapidly degraded, . In healthy, non-hospitalized people, measurement of reverse T3 does not help determine - hypothyroidism exists or not
Indirectly measures number of binding sites on thyroid binding proteins occupied by T3.
1.With patients of hypothyroidism, detecting antibodies is helpful in the initial diagnosis of hypothyroidism due to autoimmune thyroiditis, following their levels over time is not helpful in detecting the development of hypothyroidism or response to therapy.
. Following antibody levels in Graves’ patients may help to assess response to treatment of hyperthyroidism, to determine when it is appropriate to discontinue antithyroid medication, and to assess the risk of passing antibodies to the fetus during pregnancy.
Graves frequency 70%, Refer davidson
1.Decreased sweating, lethargy,confusion, low speech and motor activity,anemia
Proper history-wash hands-introduce yourself-confirm pt details-explain examination –gait consent-position of pt-sitting on a chair
3-to relax sternocleidomastoid
5-not the tip, 7-asymmetrical elevation may suggest unilateral thyroid mass ,8-if a mass is a thyroglossal cyst, it will arise during tongue protrusion.
Palpation lymph nodes for local lymphadenopathy-may suggest primary thyroid malignancy metastatic spread.Note any deviation of the trachea-may be caused by large thyroid mass.
Retrosternal dullness-large thyroid mass extending posterior to the manubrium.A bruit may suggest increased vascularity –Graves disease
2. warm/hot/cold 4. Identification and localisation of functioning thyroid tissue- E or M
R/O –rule out
H&N –head and neck
The camera works with a computer to create images that detail the thyroid’s structure and function based on how it interacts with the tracer.
An RAIU evaluates the function of the thyroid gland. When thyroid absorbs the radioactive iodine, it processes the iodine to make thyroid hormones. By measuring the amount of radioactive iodine thyroid gland, we can evaluate the way of producing thyroid hormones.
An RAIU is performed 6 to 24 hours after taking the radionuclide. You’ll sit upright in a chair for this test. The technologist will place a probe over your thyroid gland, where it will measure the radioactivity present. This test takes several minutes.
The radioactive iodine in your body is passed when you urinate. You may be advised to drink extra fluids and empty your bladder often to flush out the radionuclide. To protect others from exposure ,doctor may advise you to flush twice after using the toilet for up to 48 hours after the test.Can resume your normal diet and activities immediately after any thyroid scan.
Preparing for a thyroid scan
Tell your physician about any prescription or over-the-counter medications you’re taking. Discontinue thyroid medication from four to six weeks before your scan. Some heart medications and any medicine containing iodine also may require adjustments.
Computerised tomography,2-, although ultrasound is usually the test of choice, A computerized tomography scan (CT or CAT scan) uses computers and rotating X-ray machines to create cross-sectional images of the body. These images provide more detailed information than normal X-ray images. They can show the soft tissues, blood vessels, and bones in various parts of the body.
Cancer-extension,mass effect, invasion ,recurrence
4-To obtain material for special laboratory investigations aimed at defining prognostic parameters.
A follicular adenoma is a benign encapsulated tumor of the thyroid gland. It is a firm or rubbery, homogeneous, round or oval tumor that is surrounded by a thin fibrous capsule. A follicular adenoma is a common neoplasm of the thyroid gland, follicular carcinoma looks like adenoma.
Adenopathy means swelling of glands which secrete tears, sweats, hormones…
1-This test uses a small needle. You’ll be awake, and the most you’ll feel is a small pinch. So you probably won’t need any numbing medicines.
With the help of ultrasound imaging, your doctor places the needle into your neck to pull out a sample for testing. You may feel the needle move around a little. And your doctor might repeat it a few times to get at different parts of the nodule or goiter.
Your doctor might take samples from lymph nodes near your thyroid as well.
The procedure takes about half an hour. You may get a small bandage where the needle went in. Then, you can go on with the rest of your day.
2-This is like FNA, but with a bigger needle. If your doctor doesn’t get clear answers from an FNA biopsy, this one might be a good backup plan. Researchers are still looking at when and how to best use it.
3. Doctors rarely use this method on the thyroid. It requires making an opening in your neck to remove the node. It may even mean removing half your thyroid. Because it’s surgery, you’ll get medicines to put you under during the operation. It also means a longer recovery.
The thyroid gland requires two very important biologically active substances to function properly –Iodine and thyrosine Thyrosine is an non essential aminoacid that is made in the body from Phenylamine , an essential aminoacid found naturally in P to B
Selenium is a micronutrient needed for the synthesis of thyroid hormones, T4 to T3,antioxidant defence activity
Vit D still not clear, Ca rich foods interfere with levothyroxine absorption.Gap of 4 hrs recommended
CRUCIFEROUS VEGETABES-inhibit production of thyroid hormnes, cooked form once in while, raw consumption must restricted
TG develops 3rd or 4th week of gestation, foetus syntheis start by 11th or 12th week.Normally in pregnancy increase metabolic demands
1-TSH supressed, T3 and T4 elvated , antibodies +ve.RAIU test cant do , Radioactive iodine cross placenta and damage fetal thyroid gland permanently
Grves disease is the most common cause of thyrotoxicosis in pregnancy SSI, thyroid stimulating hormone binding inhibitory immunoglobulin
Thyroid storm –fever, fast irregular heart beat, vomiting, diarrhoea
Hyperhidrosis –excessive sweating, flush – feeling of warmth, pretibial myxedema- asymmetric, firm plaques with peau d orange appearance.