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)
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EUTHYROIDSUB-CLINICALHYPERTHYROID
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SUB-CLINICALHYPOTHYROID
SECONDARYHYPERTHYROID
SECONDARYHYPOTHYROID
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PRIMARYHYPOTHYROID
LOW NORMAL HIGHTHYROID STIMULATING HORMONE - TSH