Endocrine 6: Disturbances in TH Flashcards
Disturbaces in thyroid horomones can be classified into
- Primary: disease in thyroid gland
- Secondary: disease in pituitary gland
- Tertiary: disease in Hypothalamus
describe thyroidal causes of hypothyroidism
- Congenital: absence of thyroid gland or defect in biosynthesis of thyroid hormones
- Maternally transmitted: mothers taking antithyroid drugs or excessive iodide
- Chronic iodine deficency: now rare
- Latrogenic: excess antithyroid drugs, removal of thyroid tissue in surgeory, overdose in radioactive iodine therapy in cases of Hyperthyroidism
- Chronic thyroiditis: autoimmune or viral infection
general effect of hypothyroidsm
- decreased BEE, calorigenesis, body temperature
- more succeptibilty to cold weather
- Increased body weight
- accumulations of subcutaneous mucoproteins & mucopolysaccarides causing non-pitting edema
- dry coarse skin
- Decreased activity of all body systems
age specific effects of hypothyroidism is divided into:
- Cretinism: in children since birth or early childhood
- Myxedema: adults
Charactaristics of Cretinism
Mental delay:
* unable to learn
* Low IQ
* unable to control urine & stool
* unable to sit, stand, walk, speak properly
Physical growth delay:
* Short in height
* fontanels close later
* teeth erupt later
* Delayed milestones of growth
Sexual delay: impotent & sterile
Antomical charactrasitics:
1. wide nasal bridge
2. enlarged lips
3. protruded tongue
4. abdominal bulge with umbilical hernia
5. Supraclavicular pad of fat
Charactaristics of Myxedma
- Patient hates winter
depressed mental function:
* Apathetic
* dorwsy
* prolonged reaction time
Husky voice
abscent outer 1/3 of eye brows
Sexual functions are depressed, causing atrophy of gonads
another name for hyperthyroidism
thyrotoxicosis
hyperthyroidism causes are divided into:
- thyroid overactivity
- supra-thyroid ovaractivity
- Extrathyroidal
causes of thyroid overactivity
- Acute thyroiditis
- Tumor
- Grave’s disease: antibodies stimulate thyorid gland instead of TSH
causes of suprathyroid overactivity
- Pituitary thyrotrope tumor
- Resistance of thyroid hormone receptors of ptuitary –> inhibiting negative feedback
Extrathyroid causes of Hyperthyroidism
- Ectopic thyroid tissue from tumor
- Excessive adminstration of thyroid hormones by error
Symptoms of Hyperthyroidism
- Increase BEE & body temperature, patient doesn’t like hot weather
- Loss of body weight (in spite of increased appetite & hyperphagia)
- Increases excitability of Nervous system–> Reticular Activating System –> nervousness & fine tremors
- Increased Heart rate & Cardiac output
- Increased systolic BP
- Decreased diastolic BP due to peripheral VD caused by metabolite accumulation
- Increased pulse pressure
- Exophthalmos
Explains why hyperthyroidism causes Tachycardia
- Direct stimulation of SAN
- Thyroxines (thyroid hromones) sensitizes SAN to Catecholamines
- Due to increased metabolism, it leads to increased Venous return & reflex tachycardia = Brainbridge reflex
definition of Exophthalmos
protrusion of the eyeballs in Some patients with hyperthyroidism
Causes of Exophthalmos in hyperthyroidism
- Cytotoxic auto-antibodies formed against thyroid gland
- they also act on extraocular muscles
- Hypertrophy of extraocular muscle & retroorbital CT
- push the eye foreward
