Endocrine-thyroid Flashcards
Action of Follicle cells (Acini) in the thyroid gland
Stores thyroglobulin & thyroid hormone
What does the thyroid gland do?
Maintains optimal metabolism for tissue function
Autonomic innervation
Hypothalamus (TRH)….pituitary (TSH)…thyroid (THs)
What are the thyroid hormones?
T3 (triiodothyronine)-active form
T4 (thyroxine)
T3 is synthesized from________or_______in peripheral tissues
Tyrosine metabolism
OR
Conversion of T4
T3 can increase_________&______ and cause________
O2 consumption & metabolism
Protein catabolism
T4 is synthesized from
Tyrosine
T4 is the pro hormone for
T3
T4 accounts for _____of TH
80%
T4 physiologic effects is related to
Conversion & action of T3
Calcitonin is released by
Thyroid gland
Calcitonin is a ______hormone
Polypeptide
Calcitonin decreases concentration of ______ions ini plasma
Ca+
Decreased concentration of Ca+ ions ini the plasma_____, ______&______
Weakens osteoclasts
Strengthens osteoblasts
Decreases renal tubular reabsorption oof Ca & Phosphate
What is primary hypothyroidism?
Deficient thyroid hormone production
Iodine Deficiency
Autoimmune disease
What is secondary (central) hypothyroidism?
Dysfunctional pituitary gland or hypothalamus
What is exogenous hypothyroidism?
Caused by a medication side effect, by surgery or radiation of neck/head
How to manage hypothyroidism
TH replacement therapy
Monitor TSH/free T4
What is Levothyroxine (Synthroid)
Synthetic thyroxine T4
MOA of levothyroxine
Conversion of T4 to T3 ini peripheral tissues
T3 will then bind thyroid hormone receptors and affect DNA transcription
DNA transcription will increase metabolism/SNS activity/growth & development
What is Liothyronine
A synthetic isomer oof triiodothyronine (T3) and is 3x more potent than levothyroxine
What do clinical trials say about Liothyronine
Little to no effect on hypothyroid symptoms, so may be prescribed T4-T3 combo
Levothyroxine may cause_______with _______&______
Synergistic
Anticoagulants & Epi
Abnormal thyroids in a patient will cause
Exaggerated response to anesthetics & opioids, causing sedation & delayed emergence
Respiratory depression & muscle weakness
Vasopressor-Resistance HOTN
Bradycardia & diastolic dysfunction
Diminished response to alpha/beta adrenergic drugs
Metabolic abnormalities like hypoglycemia, anemia & hypothermia
What is hypothyroid effect on MAC?
No effect
What is HYPERthyroidism
Excess production & secretion of thyroid hormone
What are some disease processes related to hyperthyroidism
Graves disease (autoimmune disorder of TSH-receptor antibodies)
Hashitoxicosis (Autoimmune)
Toxic adenoma/goiter (hyperplasia or thyroid follicular cells)
What is the treatment of hyperthyroidism
Anti-thyroid drugs
Radioiodine
Surgery
Monitor TSH/T3/T4
What are risk factors for thyroid storm?
Surgery
Trauma/acute illness
Pregnancy
Symptoms of thyroid storm
Hyperthermia
Agitation/delirium/seizures
Tachy/Afib
HF
Jaundice & diarrhea
What drug can treat hyperthyroidism
Thionamides
MOA for Thionamides
Inhibit thyroid peroxidase (will decrease oxidation of thyroid hormone)
Inhibits formation of TH
Reduces concentrations of antithyrotropin-receptor antibodies
PTU also inhibits deiodiniation of T4 to T3
What should be monitored with Thionamides
Serum T4 & T3 assessment of euthyroid state
Thionamides adverse effects
Urticaria/skin rash
Arthralgia
GI issues
Agranulocytosis
Granulocytopenia
Hepatic toxicity
Monitor WBC
Potassium Iodides treat
Hyperthyroid
Two Potassium Iodides medications
Potassium Iodide
Or
Potassium iodide-iodine (Lugols)
MOA for Potassium Iodides
Decreases iodine uptake by thyroid, TH synthesis & release/thyroid size, & thyroid vascularity
Adverse effects of Potassium Iodides
Allergic reaction (rare)-angioedema or laryngeal edema risk
Bleeding disorder
What is the definitive treatment for Graves
Radioactive Iodine
MOA for Radioactive Iodine
Rapid & efficient uptake by the thyroid gland cells
Iodine isotopes trapped in thyroid
Beta rays destroy cells w/minimal to no damage to surrounding tissues
Precautions of Radioactive Iodine
Hypothyroidism risk
Contraindicated in pregnancy
Adverse effects of Radioactive Iodine
Radiation toxicity
Infertility
Anesthesia considerations with hyperthyroidism
CV risk like arrhythmia, tachycardia, ischemia or HF
CV risk associated with hyperthyroidism are best controlled by a
BETA Blocker (propranolol) IV to inhibit conversion of T4 to T3, which will control tachycardia, HTN and fever
0.5-1mg over 10min
What 2 medication can be given together ini high risk patients requiring urgent surgery for hyperthyroidism?
Iodine & thionamides
