Thyroid Flashcards
- Function: Controls apptetite, Temperature, Sex drive, Weight, mood, Sleep, Thurst
Hypothalamus Controls by ?
Controls **Pituary Hormones **by releasing Hormones :
* Thyrotropic - releasing hormone (TRH)
* Grownth Hormone- Releasing Hormone (GHRH)
* Corticotropin - releasing Hormone (CRH
* Gonadotropin- releasing Hormone(GRH)
Pituary Gland
Another Name
Master Gland
Pituitary Gland
Anterior Pituatary
TSH
Prolactin
GH
ACTH
LH
Pituatary Gland
Posterior Pituatary
ADH
Oxytocin
Thyrotropin -Releasing Hormone (TRH)
Stimulates the release of thyroid-stimulating hormone (TSH) and prolactin from the anterior pituitary.
Growth Hormone-Releasing Hormone (GHRH):
Stimulates the secretion of growth hormone (GH) from the anterior pituitary.
Corticotropin-Releasing Hormone (CRH):
Adrenocorticotropic hormone (ACTH) from the anterior pituitary.
Gonadotropin-Releasing Hormone (GnRH):
Stimulates the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the anterior pituitary.
Thyroid Gland
Function
Controller of metabolism
Energy use
Oxygen consumption
Heat Production
T4 another name
Thyroxine (another name )
Thyroxine (T4)
- **Major Thyroid Hormone secreted
- 4 Iodine Atoms
- T4 more occurate Hormone measure for clinical significant**s
- Iodine is element needed for production of hormone
- Iodine is not produce by body, must be ingensted with diet
- Thyroid has active mechanism that able to pick up iodine in blood stream
- T4 active in tissues they pick up iodine untile it’s converted T3
- T4 to T3
Triodothyronine
T3 ( anoter name )
T3 Triiodothyronine
T4 convereted to T 3 removal iodine atom in Liver
Thyroid Stimulating Hormone (TSH)
- Activated in Pituatary
- Less T4 more TSH
- More T4 less TSH
Somatrostatin
- Released from Hypothylamus
- Ability to inhibit (stop) TSH release
THyroid Function
Thyroid Hormone Uses
T3 and T4
- Facilitate normal growth and development
- Increases metabolism
- Increases catechlamine effects
TSH
- Most useful marker for thyroid function
- Follows a diurnal rhythms, peaks at midnight
Metablic Effects of T3
- Stimulates lipolysis and release of free fatty acids and glycerol
- Stimlates metabolism of chelesterol to bile acids
- Induces expression of lipogenic enzymes
- Facilatates rapid removal of LDL from plasma
- Effects chelsterol metabolism
- Stimulates aspect of carbohydrate metabolism and the pathway for protein degradation
Levels
- Normal TSH 0.3/0.5 to 3.0/5.0
- TSH level below 0.4 suggest Thyroid **overactive **
- TSH above 5.0 thyroid is underactive
Primary Hypothyroidism
-
U.S.A most common cause : Autoimmune
* World Wide: Iodine Dyfisiansy - **Second Most Common Cause **: Post-therapetic treatment
- Thyroid Destructtion
- Medacations : Amio, Lithium, Interferon Alpha
Secondary (central ) hypothyroidism
- Deficient TSH Secretion
- Rare
Tertiary (central ) hypothyroidism
- Deficient TRH secretion
- Even mroe rare
Hypothyroidism **Signs **
- Hypotension/Bradycardia
- Brittle nail
- Hair Loss
- Decrased DTR
- Dry course skin
- Myxedema in extremities
- Puffiness of eyes/face (periorbital edema )
- HYpglycemia
- Decreased bowel sound/constipation
- Goiter( not present in all pts )
Hypothyroidism** Symptoms**
- Weight gain; inability to lose weight
- Extreme fatigue
- Forgetfulness
- Prutitus
- Depression
- Cold intolerance
- Menstual irregulatiriet
- Muschle Cramps
Initiate Work Up
Not Bound = T4 : Able to enter body Tissue
Initial Work up :
**TSH **
- **Normal Range: **0.47-4.68
- Suppresed: Hyperthroidism
- Elevated: Hypothyroidism
Abnormal TSH what next
- Check FT 4
- Elevated T4 = Hyperthyrodism
- Suppressed= Hypothyroidism
**T3 : Check for Hyperthoidism or Determines Severtiy Hypothyroidism **
2 antibodies
- Antithyroglobulin antibodies
- Antithryoidism Peroxidase antibodies
Subclinial Hypothyroidism Overview
- Rises with age, highter rate in females
- Elevated TSH and normal T3/T4
- Symptoms may be presen or absent
treament quidelins
- TSH> 10 mU/L : consider tx
- TSH upper limit of normal to 9.9 :
1. <65 consider tx
2. > 65 tx with symptoms
3. >80 yrs : avoid tx
Hypothyroidism Treatment Plan
Target Goal
- Replace thyroxine to mimix normal, physiologic leveles
- Alleviate signs, symptoms, and biochemical abnormalities
Levothyroxine
Initiate dose
At 1.6mg/kg/day
Recheck TSH
6 to 8 wks
* Adjust Levopthyroxine by 12.5 to 25 mcg/day
Hypythyroidism/Myxedema Coma :
What is Hallmark Signs ?
Decreased LOC and Hypothermia
Myxedema : Clinical Presentation ?
- Hyponatremia
- Hypoglycemia
- Hypoventilation
- Hypotension
- Bradycardia
- CHF
- Severe hypothyroidism W/High Mortality
Myxedema Labs
TSH, FT4, Cortisol (will be low ) , ABG
Pharmacology Reduction of Levothyroxine Effectivenss :
**Malabsorption Syndromes **
- Postjejunoiletal Bypass Surgery
- Short bowel Syndrme
- Celiac Syndrome
Pharmacology Reduction of Levothyroxine Effectivenss :
**Reduced Absorption **
- Colestipol Hydrochloride
- Sucralfate
- Ferrous Sulfate
- Food ( soybean Formula)
- Aluminum Hydroxide
- Cholestyramine
- Sodium Polystyrene Sulfonate
Pharmacology Reduction of Levothyroxine Effectivenss :
**Drugs that Increase Clearance **
Rifampin
Carbamazepine
Phenytoin
Pharmacology Reduction of Levothyroxine Effectivenss :
Factors That Reduced T4 to T 3 Clearance
Amiodarone
Selenium Deficiency
Pharmacology Reduction of Levothyroxine Effectivenss :
Other Mechanisms
Lovastatin
Sertaline
Euthroid Sick
- Low Serum Levels of thyroid Hormones
- Nonthroidal Systemic Illness (trauma, DKA, Anorexia, Cirrohois, Malnutrition, sepsis)
- Most likely due to decreased peripheral conversion of T4 to T 3 , decrease clearance of reverse T 3
- **Labs: Do not have Elevated TSH ; Cortisole Level is Hight ;
- Where Hypothyroidism Cortisole Levels is Low **
Euthryroid Sick : Dx
- Excluson of Hypthyroidism
- Check TSH
- Directed toward underlying illness
- Thyroid Hormone replacment DO NOT Indicated
Hyperthyroidism
Thyrotoxicosis VS Hyperthyroidism
**** Thyrotoxicosis: Clinical Syndrome of expcess circulating thyroid hormones irrespective of source
* Can be due to too much Levothyroxine . Too much thyrotoxicosis floating in body
* Hyperthyroidism: * * Sustained increased in Thyroid hormone synthesis and secretion from the *thyroid gland *
Hyperthroroidism
Cause
- **Autoimmune (Graves’ disease) **
- Toxic nodular goiter
- Thyroiditis
- Exogenous Iodine
- Amiodarone Toxicity
- Excessive ingestion thyroid hormone replacement
- TSH secreting pituitary adenoma
**Hyperthyroidism **Signs **
- Hypermetabolism
( classic symprom loosig weight and eating more ) - Hyperrreflexia
- Tachycardia
- Hypertension
- Warm, moist, thinning of skin
- Fine/thin hair
- Goiter
- Exophthalmos
Hyperthyroidism
**Symptoms **
- Palpitations
- Fatique
- Sweating
- Anxiety
- Insomnia
- Mentrual irregulatirties
- Heat Intolerance
- Myalgias, Muschle weakness
Hyperthoroidism :
Grave’s Desease
- Most common cause of hyperthyroidism in the uS
- 7 to 8 times more common in women than men
- Autoimmune Disease
- **TRAb or TSI **
- Overactivity of the **thyroid gland **
GRave’s Disease Clues ?
- Exopthalmos
- Enlarged thyroid Gland
- Family hx of autoimmune diseas
Hyperthyroidism:
Exophthalmos
**Associated with Graves’ Disease
* Inflammation of **retro-orbital tissues **
* Optic nerve compression and atrophy
Hyperthoroidism
Exophthalmos
**Symptoms **
- Eye discomfort, grittiness
- Excess tear production
- Phorophobia
- Diplopia
- Decreased Acuity
Hyperthoroidism
Exophthalmos
Signs
- Exophthalmos
- Ophthalmoplegia ( weakness or paralysis of one or more of the muscles that control eye movement. )
* - Periorbital edema
Initiated Work Up
TSH
- **TSH **
- Normal Range 0.47 to 4.68
- Supressed = Hyperthyroidism
- Elevated= Hypothyroidism
Initiated Work Up
TRAb
**TRAb
**Positive = Graves’ Disease
Negative= Further Work up **
Initiated Work Up
Elevated FT4 and T 3
- Total T 4: measure Bound /Free Hormone
- FT4 : Not Bound / able to enter tissues for effectiness
- Total T 3 : Support dx Hyperthyroidism / Dx Severity Hyperthyroidism
**Elevated FT4 and T3
Elevated: Hyperthyroidism
Suppressed: Hypothyroidism **
Thyroid Scan
- Find out if thyroid Glan is over reactive or toxic nodules goiter or thyroitis
- Test if thyroid glan can collect iodien
- T4 collect iodine Thyroid glan collect iodine for T 4
Radioactive Iodine Uptake
Aloud us to see where iodine goes
Determin if glan is overreactive
Hi Uptake Radiosity : Graves Disease
Low Up take : HYpoactivity
Contraindicating for pregnant women
Subclinical Hyperthyroidism
Exogenous ( originates from outside of the system )
Endogenous ( within system )
Low TSH and FT4 and T 3 WNl
Thyroid Storm causes
Surgery, Infection, Traume. Acute Iodine load . Abrupt cessatio of anti-thyroid medication
Thyroid Storm Symptoms
fever
Agitation and confusion
Tachycardia
Hyperglycemia
HTN
RR distress
N/V
TX of thyroid STorm
- TX underlying Cause
- BB (propranolol )
- Thionamide (PTU or Methimazole )
- Iodine Solution (SSKI or Lugol’s solution )
- Glucocotroicoids (Hydrocortisone 100 mg Q 8 hr s)
- Antipyretics
- Supportive care
- Admit to ICU
