Thyroid Disease Flashcards
what’s the major secretory cell of the thyroid gland?
follicular cells
C cells also called ___ secrets ____
parathyroid cells
calcitonin
What are the four steps of thyroid hormone synthesis?
- iodide uptake
- activation through oxidation into iodine
- iodination
- coupling of iodinated tyrosine
which thyroid hormone effects the gene expression?
T3
which causes increased calcitonin level?
increased serum calcium level
what stimulates the release of T3 and T4
extreme cold
catecholamines
gonadal and adrenocortical increased steroids
what decreases the release of T3 and T4
growth hormone inhibiting hormone
dopamine
most common causes of primary hyperthyroidism
Grave’s disease
toxic mutinodular goitre
follicular adenomas
common causes of secondary hyperthyroidism
pituitary adenomas (TSH-secreting)
other causes of thyrotoxicosis
excess thyroid medicaiton
ectopic thyroid tissue
chorionic gonadotropic secreting tumors
gestational thyrotoxicosis (often associated with hyperemesis gravidarum)
symptoms of hyperthyroidism are due to
increase metabolic rate
increase CNS stimulation
thyroid hormone antagonist to
insulin
Grave’s disease is a ______
autoimmune
hypersensitivity type II (cytotoxic)
autoantibodies___ bind to the TSH receptors
TSH receptor antibodies or
TSI (thyroid stimulating immunoglobulins)
clinical distinguishing factor of Grave’s disease are
Ophthalmopathy: functional and infiltrated (exophthalmos)
Dermopathy: Pretibial myxedema
Graves ophthalmopathy is a result of
Production of glycosaminoglycans, which lead to edema and fibrosis
nodular thyroid disease diagnosis
Palpable thyroid nodules
Ultrasonography
FNA
nodular thyroid disease treatment
medication (Methimazole and propylthiouracil)
radiation
surgery
first line treatment for hyperthyroidism
Methimazole (Tapazole)
side effects of thionamides
Hepatotoxicity
Hypothyroidism
Rare agranulocytosis is the most dangerous toxicity
Methimazole (Tapazole) dosing
Initial:
Mild disease: 5 - 15 mg once daily
Moderate to severe disease: 30 - 40 mg once daily
Severe disease or large goiters: 60 mg once daily
Maintenance: 5-15 mg once Daily
Methimazole (Tapazole) contraindication
Crosses placenta; avoid in first trimester
Found in breastmilk, but compatible with breastfeeding at lower doses
Safe for use in infants and children (preferred agent)
Propylthiouracil (PTU)
Preferred treatment in pregnancy (compared to methimazole) as crosses the placenta LESS readily
Minimal transfer into breastmilk, but concern for potential neonatal hepatotoxicity → avoid in breastfeeding (methimazole is preferred choice)
Avoid in children if possible due to high risk of hepatotoxicity
adjunctive therapy for hyperthyroidism
β-Blockers and nonradioactive iodine may be used as adjunctive therapy
thyroid storm symptoms
Profound hyperthermia
Restlessness, agitation, tremor, or delirium
Severe tachycardia (especially atrial tachycardia)
High-output heart failure
Nausea, vomiting, diarrhea which contribute to fluid volume depletion
thyroid storm treatment
PTU (preferred) or methimazole
Beta-blockers for CV symptoms
Glucocorticoids
Iodine (nonradioactive for acute care)
ICU and supportive care
Lab Tests for hyperthyroidism
TSH (Biotin can cause false abnormalities)
T3
T4
TSH-R-Ab
hyperparathyroidism (increased PTH) causes
hypercalcemia and hypophosphatemia
3 types of hyperparathyroidism
- primary: adenomas, hyperplasia, carcinomas
- secondary: conpensation to chronic hypocalcemia
- tertiary: autonomous secretion of PTH and hypercalcemia (from severe CKD or kidney transplant)
PTH in bones
stimulates osteoblasts to make RANK-L- stimulates osteoclasts to increase bone resorption –> release of calcium and phosphate into the blood
PTH in kidney
Calcium reabsorption
Phosphate excretion
Vitamin D activation
Parathyroid hormone increase ___, decrease _____
Parathyroid hormone = ↑ serum calcium, ↓ serum phosphate
Primary Hyperparathyroidism symptoms
(excessive calcium)
bones
stones
groans
thrones: nephrogenic diabetes insipidus
psychiatric overtones
Primary & Tertiary:
Hyperparathyroidism
symptoms
Hypophosphatemia (primary); variable phosphate levels in tertiary
Increased active vitamin D (1,25-di-hydroxy-vitamin D3)
Secondary hyperparathyroidism symptoms
Hypocalcemia
Hyperphosphatemia
Decreased active vitamin D (1,25-di-hydroxy-vitamin D3)
____ (thyroid condition) is more common in older adults
hyperthyroidism
TSH___ in the 1st trimester due to
TSH decrease in 1st trimester due to hCG–> thyroid hormone secretion is stimulated–>. increased serum T4 –> negative feedback reduce TSH secretion
Untreated maternal hypothyroidism
associated with ↑ risk of low birth weight and impaired neurocognitive development
postpartum thyroiditis
Autoimmune mediated
Biphasic presentation:
Transient thyrotoxicosis due to release of stored TH from the thyroid gland (↓ TSH, ↑ T4/T3, possible +TPO Ab)
Hypothyroid phase (↑ TSH, ↓ T4/T3), followed by return to euthyroid state by end of the first postpartum year
congenital hypothyroidism symptoms
hoarse cry, large posterior fontanelle, large tongue, difficulty eating, umbilical hernia, prolonged jaunidice, constipation, lethargy, hypothermia, delayed growth, long-term cognitive disability
The period at greatest risk to the newborn for a pregnant person with hypothyroidism is
1st trimester
