Dr PRABHAT AGRAWAL

PG DEPARTMENT OF MEDICINE SNMC AGRA

Primary – autoimmune – hashimotos thyroiditis,atrophic thyroiditisIatrogenic;I131 treatment ,subtotal or total thyroidectomy; external irradiation of neck for lymphoma or cancerDrugs-iodine excess(including iodine containing contrast media and amiodarone)lithium ,antithyroid drug,p-amino salisalic acid,interferon alphaCongenital hypothyroidism-absenteectopicthyroid,dyshormonogenesis,tsh-r mutation iodine defieciencyInfiltrative disorder-amylodosis,sarcoidosis,hemochromatosis,scleroderma,cystinosis, riedels thyroiditis

Transient-silent thyriditis,including post partum thyroididtisSubacute thyroiditisWithdrawl of thyroid treatment in indiviual with intact thyroid

Secondary-hypopituitarism:tumour ,pituatry surgery or irradiation,infiltrative disorder,sheehans syndrome,trauma,genetic form of combined pituatryhormone deficienciesIsolated Tsh deficiency or inactivityBexaretone treatment

Signs and symptom of hypothyroidismSymptomsTiredness,weaknessDry skinFeeling cold,hairlossHair lossDifficultyconcentrati

ng and poor appetiteDysponeaHoarse voiceMenorrhagia(later

oligomenorrhea)

SignsDry coarse skin cool

periphral extremities

Puffy face,hands,and feet (myxedema)

Diffuse alopeciaBradycardiaPeripheral edemaDelayed tendon

reflexationCarpal tunnel

syndrome

Clinical Manifestations of Hypothyroidism -- Skin

Cool and pale skin blood flow Dry roughness of skin the epidermis has an

atrophied cellular layer and hyperkeratosis Decreased sweating calorigenesis and

acinar gland secretion Generalized nonpitting edema (myxedema) in

severe hypothyroidism infiltration of the skin with glycosaminoglycans and associated water retention

Clinical Manifestations of Hypothyroidism -- Eyes

Periorbital edema -- as a manifestation of generalized nonpitting edema or Graves' ophthalmopathy.

Graves' ophthalmopathy may persist or worsen when hypothyroidism develops after treatment of Graves' hyperthyroidism. Patients will have variable degrees of stare, protrusion of the eyes, and extraocular muscle weakness.

Clinical Manifestations of Hypothyroidism -- Cardiovascular System

Bradycardia reductions in heart rateImpaired muscular contractilityReduced cardiac output decreased exercise

capacity and shortness of breath during exercise ECG: low voltage of QRS complexes and P and T

wavesCXR: cardiomegaly interstitial edema,

myofibrillary swelling, LV dilatation, pericardial effusion

Clinical Manifestations of Hypothyroidism -- Cardiovascular System

Myxedema induces coronary artery disease ??

CAD more common in p’ts with hypothyroidism

Symptoms and signs of congestive heart failure are usually absent in patients who have no other cardiac disease

Congestive heart failure or angina may worsen when hypothyroidism develops in patients with heart disease

Clinical Manifestations of Hypothyroidism -- Cardiovascular System

Hypertension peripheral vascular resistance In normotensive patients, BP increases are

small (<150/100 mmHg). The BP of patients with established

hypertension may increase further with the development of hypothyroidism.

Clinical Manifestations of Hypothyroidism -- Gastrointestinal Disorders Constipation, even ileus gut motility Decreased taste sensationGastric atrophy presence of antiparietal

cell antibodies. Pernicious anemia occurs in 10% of patients with hypothyroidism caused by chronic autoimmune thyroiditis.

Weight gain decreased metabolic rate + accumulation of fluid (nonpitting edema) that is rich in glycosaminoglycans

Ascites, rare

Clinical Manifestations of Hypothyroidism -- Neurological Dysfunction

General depression of central nervous system function

Sleepiness, inability to concentrateSluggish thought processes

Respond slowly to questionsLess able to retrieve information from memory

Agitated psychosis, rare (“myxedema madness”)PET: 23% reduction in cerebral blood flow and a

12% reduction in cerebral glucose metabolism

Clinical Manifestations of Hypothyroidism -- Neuromuscular Abnormalities

A delay in the relaxation phase of deep tendon reflexes

Carpal tunnel syndromeParesthesia Asymptomatic elevation in serum CPK

level to muscle hypertrophy (which may be accompanied by muscle cramps) to proximal muscle weakness to, in rare cases, rhabdomyolysis.

Clinical Manifestations of Hypothyroidism -- Metabolic Abnormalities

Hyponatremia may result from a reduction in free water clearance

Reversible increases in serum creatinine occur in 20 ~ 90% of hypothyroid patients

lipid clearance may be decreased, resulting in an elevation in the serum concentrations of free fatty acids and total and low-density lipoprotein cholesterol

Plasma homocysteine concentrations are increased in some hypothyroid patients,

Clinical Manifestations of Hypothyroidism -- Respiratory System Fatigue, shortness of breath on exertion,

and decreased exercise capacity impaired respiratory function + cardiovascular disease

Hypoventilation (shallow and slow respirations) respiratory muscle weakness + reduced pulmonary responses to hypoxia and hypercapnia

Obstructive sleep apnea macroglossia

Clinical Manifestations of Hypothyroidism -- Renal Function

Decreased glomerular filtration rate (GFR )

Impaired ability to excrete a water loadThe drug clearance (ex, antiepileptic,

anticoagulant, hypnotic and opioid drugs), is decreased. Drug toxicity may occur if drug dosage is not reduced.

During T4 replacement, drugs that are administered at effective doses in patients who are hypothyroid may become less effective.

Clinical Manifestations of Hypothyroidism -- AnemiaImpaired hemoglobin synthesis thyroxine

deficiencyIron deficiency increased iron loss with

menorrhagia + impaired intestinal absorption of iron

Folate deficiency impaired intestinal absorption of folic acid

Pernicious anemia vitamin B12 -deficient megaloblastic anemia

Clinical Manifestations of Hypothyroidism -- Reproductive Abnormalities

Women with hypothyroidism may have either oligo- or amenorrhea or hypermenorrhea-menorrhagia.

Decreased fertility Increased likelihood for early abortion Hyperprolactinemia may occur, and is

occasionally sufficiently severe to cause amenorrhea or galactorrhea

The serum sex hormone-binding globulin concentration may be low in hypothyroidism. This will lower serum total but not free sex hormone concentrations.

features Primary secondaryskin Thick and without

wrinkleThick with fine wrinkle

Hair coarse fineMenstrual irregularities

menorrhagia amenorrhea

Secondary sexual changes

Normal poor

Heart size May be enlarged smallGoitre May be present absentSoft tissue edema Marked absentBlood pressure Normal or high lowcholestrol increased normalTSH high lowPlasma cortisol normal lowTRHstimulation test Exaggerated response No response

Thyriod auto anti bodies

May be present absent

Differentiation between primary and secondary hypothyriodism

Hashimoto’s ThyroiditisChronic lymphocytic thyroiditisProbably the most common cause of

hypothyroidismWith goiter(younger patients) or without

goiter (older patients – atrophy gland after destruction by immunologic process)

High titer of autoantibodies to thyroidal antigens (Thyroglobulin Ab, Thyroperoxidase Ab = TPO Ab = Antimicrosomal Ab = AMA)

LO

W

N

OR

MA

L

HIG

H

FREE

TH

YRO

XIN

E o

r FT

4

EUTHYROIDSUB-CLINICALHYPERTHYROID

NON THYROIDILLNESS - NTI

NTI or Pt.on ELTROXIN

SUB-CLINICALHYPOTHYROID

SECONDARYHYPERTHYROID

SECONDARYHYPOTHYROID

PRIMARYHYPERTHYROID

PRIMARYHYPOTHYROID

LOW NORMAL HIGHTHYROID STIMULATING HORMONE - TSH