Thyroid, Parathyroid, and Steroids Flashcards
TRH
Thyrotropin Releasing Hormone
-stimulates anterior pituitary to secrete TSH
TSH
Thyroid Stimulating Hormone
-stimulate thyroid to secrete T3 and T4
T3
Tri iodo thyronine
- Active
- 10% of secreted thyroid hormone
T4
- Converted to T3 in the liver
- 90% of secreted thyroid hormone
Hypothyroidism
Decreased secretion of thyroid hormones
- Primary causes: Hashimoto’s, removal of thyroid, thyroid gland ablation, drug induced
- Secondary causes: pituitary issue
Signs and Symptoms of Hypothyroidism
- Bradycardia
- Feeling cold
- Decreased appetite
- Weight gain
- Constipation
- Fatigue
- Dry Skin
Levothyroxine
Synthetic T4 that must be converted to active form in periphery
- Monitor TSH
- Can cause nausea, vomiting, diarrhea, and insomnia
Levothyroxine DDIs
- Phenytoin, Carbamazepine
- Warfarin
- Fiber, Cholestyramine
- Sucralfate
- Rifampin
- Calcium, antacids
Administer Levothyroxine
Give 30-60 minutes prior to any meal or other medications
Liothyronine
Synthetic T3
-Does not need to be converted but not as reliable or efficacious & short half life
Liothyronine ADRs
Severe cardiac effects: tachycardia, arrhythmia, MI, hypotension
Desiccated Thyroid
Mix of T3 and T4 from ground up pig thyroid
-monitor TSH frequently because of issues with consistency
Hyperthyroidism
Increased thyroid hormone activity
-causes: graves’ disease, Plummer’s disease, Iodine induced, Excessive Pituitary TSH, Excessive ingestion of thyroid hormone, Thyroiditis, Lithium
Signs and symptoms of Hyperthyroidism
Palpitations/Tachycardia Irritability Nervousness/tremor Increased bowel movements Goiter Hunger Heat intolerance Weight loss Insomnia
Thioamides MOA
STOP synthesis of thyroid hormones via inhibition of thyroid peroxidase (for Hyperthyroidism)
- drug is iodinated instead of iodide
- no effect on circulating T3 or T4
Thioamides Drugs
Methimazole (Preferred)
Propylthiourazil (frequent 3x dosing and expensive)
Thioamides ADRs
Edema Alopecia Possible Agranulocytosis Liver Damage Vasculitis with Propylthiouracil
Sodium Iodide (Radioactive I)
Used for Hyperthyroidism; mimics iodide and is taken up by thyroid
- destroys gland cells, shrinks size of thyroid
- Used in thyroid cancer treatment
- Watch for hypothyroidism
Potassium Iodide
STOP release of thyroid hormones and hormone synthesis
- use with thioamides
- used in hyperthyroidism thyroid storm
Parathyroid Hormone (PTH)
Released from the parathyroid gland in response to decreased calcium levels
-PTH receptor on osteoclasts that moves calcium from bone into bloodstream
Osteoclasts
Bone Resorption
-used in bone removal; releases calcium and phosphorus
Osteoblasts
- Bone Formation
- used in bone building; fill in empty spaces of bone with collagen and calcium/phosphate crystals
Cinacalcet MOA
Used in hyperparathyroidism; increased sensitivity of calcium sensing receptor; decreases PTH, calcium and phosphorous which prevents progressive bone disease
What is Cinacalcet approved for?
- Hypercalcemia (Primary hyperparathyroidism and parathyroid carcinoma)
- Chronic Kidney Disease (secondary hyperparathyroidism)
- NO in hypocalcemia
Osteoporosis/Osteopenia
Decreased bone strength, quality, and mineral density (increased fracture risk)
Osteoporosis/osteopenia risk factors
- Elderly (more resorption than formation after age 30)
- post menopausal women (estrogen)
- medications
- low dietary calcium
Calcium and Vitamin D
Vitamin D increases calcium absorption in the intestines and reabsorption in the kidneys
Vitamin D supplements
Cholecalciferol (D3): more potent, longer acting
Ergocalciferol (D2)
Calcitriol- synthetic analog
Doxecalciferol- metabolized in liver, can use in kidney dysfunction
Bisphosphonates
GOLD STANDARD for osteoporosis treatment
- Decreases rate of bone resorption via inhibition of osteoclasts and osteoclast precursors (osteoclast apoptosis)
- Long half life: infrequent dosing
Bisphosphonate drugs
Alendronate
Ibandronate
Risendronate
Zoledronic Acid
Bisphosphonates ADRs
Hypocalcemia Hypophosphatemia Myalgia Osteonecrosis of the jaw* Erosive Esophagitis*
Calcitonin
Used for pain relief associated with osteoporotic vertebral fractures
- PTH antagonism, inhibiting bone resorption (activation of calcitonin receptors on osteoclasts inhibits osteoclast activity
- IV or intranasal administration
Teraparatide and Abaloparatide
For Moderate to Severe Osteoporosis (daily SC injection)
-Recombinant formulation of endogenous PTH: stimulates OSTEOBLAST function for new bone formation
Teraparatide and Abaloparatide ADR
BBW: osteosarcoma
- Mild hypercalcemia
- Orthostatic hypotension
Denosumab
SC Injection (every 6 mo) -Monoclonal antibody; RANKL inhibitor used to reduce bone resorption via blocking osteoclast activity
Denosumab ADR
Injection site reaction
possible increased risk of infection
Estrogen
Reduces osteoclast activity (does’t reverse loss)
-decreased vasomotor symptoms
Raloxifene
Selective Estrogen Receptor Modulator (SERM)
-estrogen agonist in the bone to prevent bone loss- decrease bone resorption
Raloxifene ADR
Vasomotor symptoms (hot flashes)
Cushing Syndrome
Increased ACTH production, leading to high circulating cortisol levels
-tumor on pituitary gland or excessive glucocorticoid administration (use surgery or stop medication)
Hyperaldosteronism
- adrenal gland produce too much aldosterone
- treat with aldosterone antagonist
Addison’s disease (primary adrenal insufficiency)
- An autoimmune disorder where not enough corticosteroids produced endogenously
- Treated with glucocorticoids and mineralocorticoid replacement
Secondary Adrenal Insufficiency
- Pituitary gland cannot produce enough ACTH
- Tumor: surgical removal
Cortisol
- Regulates metabolism, cardiovascular function, growth, inflammation, and immunity
- Negative feedback system
- Activates glucocorticoid receptors
- Glucocorticoids mimic the actions of cortisol
Glucocorticoids Therapeutic Use
- Inflammation
- Immunosuppression
- Replacement in adrenal insufficiency
Glucocorticoid Receptor Agonists
Betamethasone Budesonide Clobetasol Cortisone Dexamethasone Fluticasone Hydrocortisone Methylprednisone Mometasone Prednisolone Prednisone Triamcinolone
HPA Axis Suppression
- After ~1 week of glucocorticoid use, cortisol production is suppressed via negative feedback
- Abrupt cessation can lead to acute adrenal insufficiency for 2-3 days
- TAPER so body can readjust HPA axis
Glucocorticoids ADE
Hyperglycemia Immunosuppression Insomnia Psychological effects Osteoporosis Lipolysis Hormonal changes Hypertension Slowed growth in children Muscle issues Ocular issues
Avoiding glucocorticoid ADRs
- Use small dose in short duration
- local administration
Mineralocorticoids
Predominantly activated by endogenous aldosterone
Fludrocortisone
Mineralocorticoid receptor agonist
- similar to aldosterone: increased reabsorption of sodium and loss of potassium
- ADR: Dose dependent hypertension
Aldosterone Antagonists
- Used in primary aldosteronism
- Competes with aldosterone receptors in distal tubules, increasing sodium and water excretion while preserving potassium
- Used in CHF, resistant hypertension, cystic acne
Aldosterone Antagonist drugs
Spironolactone
Eplernone
Aldosterone Antagonist ADRs
Hyperkalemia
Gynecomastia
Impotence
