甲状腺功能减退
Hypothyroidism
复旦大学医学院内分泌科
李 益 明
Hypothalamic-pituitary-
thyroid axis
Overview
? Clinical syndrome
? Slowing down of metabolism
? Slowing of growth and mental retardation in
infants and children
? Generalized slowing down of organism
? Deposition of glycosaminoglycans in skin
and muscle
? Reversible with therapy
Etiology and Classifcation
? Primary(thyroid failure)
?Hashimoto’s thyroiditis
?Iodide deficiency or excessive
?Radioactive iodine therapy for GD
?Subtotal thyroidectomy
?Subacute thyroiditis
? Secondary,pituitary deficit
? Tertiary,hypothalamic dysfunction
? Peripheral resistance to thyroid hormone
Pathogenesis
? Affects each tissue
? Accumulation of glycosaminoglycans (hyaluronic
acid)
?Not to excessive synthesis
?But decreased destrution
? Increased capillary permeability
? Interstitial edema
?Skin
?Heart muscle
?Striated muscle
Clinical Features
Adults
? Symptoms
?Easy fatigability
?Coldness
?Weight gain
?Constipation
?Menstrual irregularities
? Signs
?Cool,rough,dry skin
?Puffy face and hands
?Hoarse and husky voice
?Slow reflexes
?Yellowish color skin
Clinical Features
? Cardiovascular signs
?Impaired myocardium contraction
?Bradycardia
?Diminished cardiac output
?ECG,low voltage of QRS,P,T waves
?Pericardial effusion
?Coronary artery disease
?Cardiac angina(Replacement therapy
aggravate )
Clinical Features
? Pulmonary function
?Shallow,slow respiration
?Respiratory failure
? Intestinal peristalsis
?Markedly slowed
?Constipation
? Renal function
?Decreased glomerular filtration
Clinical Features
? Anemia
?Impaired hemoglobin synthesis
?Menorrhagia and Absorption of iron?
?Folate deficiency
?Pernicious anemia
? Nuromuscular system
?Muscle weakness
?Slow reflexes
? Central nervous system symptoms
?Inability to concentrate
?Anovulatory cycles and infertility
?Depressed
Symptoms of hypothyroidism
Symptoms % of cases
Weakness 99
Dry skin 97
Coarse skin 97
Lethargy 91
Slow speech 91
Edema of eyelids 90
Sensation of cold 89
Decreaseed sweeting 89
Cold skin 83
Thick tongue 82
Edema of face 79
Coarseness of hair 76
Pallor of skin 67
Memory impairment 66
Symptomsof hypothyroidism
Symptoms % of cases
Constipation 61
Gain in weight 59
Loss of hair 57
Pallor of lips 57
Dyspnea 55
Peripheral edema 55
Hoarseness or aphonia 52
Anorexia 45
Nervousness 35
Menorrhagia 32
Palpitation 31
Deafness 30
Precordial pain 25
Myxedema coma
? Frequently in obese elderly woman
? Yellowish skin
? Large tongue
? Thin hair
? Bradycardia
? Marked hypothermia
? Lethargy progressing to stupor or coma
? Hypoventilation
? Hypotension
? Shock
Cretinism
? Etiology
?Low iodide intake and endemic goiter
?Ectopic thyroid gland
?TSH-R Ab[block] from mother
?Inherited defects in thyroid hormone
?Iodide,antithyroid drugs,radioactive iodine
? Symptoms
?Respiratory difficulty
?Cyanosis
?Jaundice
?Poor feeding
Hypothroidism in childen
? Retarded growth
? Mental retardation
? Precocious puberty
Face of hypothyroidism
Face of hypothyroidism
Laboratory Findings
? FT4:?
? uTSH:?
?sensitive to detect 0.01?u/mL
?Most sensitive
?Most convenient
?Most specific
? FT3,
?Variable
?May be within the normal range
? TPOAb,TgAb,AITD (autoimmune thyroid
disease)
? TC
Diagnosis
Symptoms+Signs
Primary
hypothyroidism
TRH test
FT4 ?+TSH ?
Secondary
hypothyroidism
Normal type
response
Excessive
response
No
response
Pituitary
lesion
Hypothalamic
lesion
FT4 ?+TSH ? or N
Primary
hypothyroidism
If?
Treatment
Drugs for hypothyroidism
LT4 Desiccated thyroid
Component T4 T4+T3
high ratio of T3 to T4
Dose 50?g 40mg
Intensity 50 ?g = 30mg
Initial dosage 25~50 ?g 20mg
Maintenaning dosage 50~150 ?g 40~120mg
Half-life 7 days 1 days
Institution of replacement therapy
? Full adrenal support first if with concomitant
adrenal insufficiency
? Beginning with low dosage
?Degress of hypothyroidism
?Age
?General health
? Increase ? tablet weekly
? Needs 6 weeks before equilibration
? Use powdered thyroid gland for myxedema coma
? Monitoring FT4 and TSH
? TSH will be suppressed in normal range in 3 mo
Side effects
? No allergy
? Overdosage
?Arrhythmia
?Paroxyamal atrial tachycardia
?fibrillation
?Insomnia
?Tremor
?Restleness
?Excessive warmth