Repro-Endo: Thyroid / Parathyroid Flashcards Preview

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Flashcards in Repro-Endo: Thyroid / Parathyroid Deck (29)
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Levothyroxine / Triiodothyronine

  • T4 analog (Thyroxine replacement) / T3 analog
  • Binds to nuclear receptors
  • Increased Protein synthesis and Metabolic rate
  • Increased Beta-receptor Increased sensitivity to Catecholamines
  • Tx: Hypothyroidism / Myxedema
  • SE: Hyperthyroidism (Tachy, Heart failure, Sweating, Tremor, Arrhythmias, Diarrhea)


Methimazole, Propylthiouracil (PTU)

  • Thionamides
  • Inhibits Thyroid Peroxidase --> Blocking Synthesis
  • Propylthiouracil (PTU) also inhibits Peripheral conversion of T4 --> T3 by blocking 5'-deiodinase
  • PTU avoided as first line treatment
  • PTU used during First Trimester in pregnancy (Teratogenic effects)
  • Tx: Hyperthyroidism, 3 Ps of PTU
  • SE: Rash, Urticaria, Fever, Nausea, Agranulocytosis, Thrombocytopenia, Acute Hepatic necrosis, Vasculitis, Hepatotoxicity (Propylthiouracil) Possible Teratogen (Methimazole)


Iodine and Radioiodine

  • Inhibits Thyroid Hormone release
  • 131I concentrated in the Thyroid gland and emits Beta and Gamma XRT
  • Drug of choice for destroying Toxic Adenoma
  • NEVER USE w/ Pregnant women
  • Tx: Thyroid Storm and Before Thyroidectome (prevents Thyroid Storm), Hyperthyroidism, Adjunctive Tx for some Thyroid cancers
  • SE: Dysgeusia (metalic taste), Excessive salvation, Diarrhea, Rash




  • Stabilizes bony matrix
  • Coats hydroxyapatite to prevent Osteoclasts from Resorbing bone
  • Tx: Postmenopausal Osteoporosis, Paget disease
  • SE: Heartburn, Erosive esophagitis, Stomach upset, Joint/Back pain, Osteonecrosis of the Jaw



  • Lowers Serum Calcium
  • Mild analgesic properties for Bone pain
  • Intranasal / Subcutaneous
  • Tx: Hypercalcemic states
  • SE: Runny nose, and Nasal discomfort, Flushing



  • Activated form of Vitamin D
  • Increases Calcium absorption from Intestines
  • Tx: Hypocalcemia, Vit. D replacement in Pts. w/ End-Stage Renal Disease
  • SE: Vit. D. Intoxication: Hypercalcemia, Polyuria, Weakness, Headache, Somnolence, and Constipation


Rx for Hypothyroidism?

Levothyroxine (T4)


Rx for Hyperthyroidism?

1st: Methimazole

2nd: PTU (Propylthiouracil)

Pregnancy: 1st Trimester = PTU, 2nd - 3rd = Methimazole


Rx for Thyroid Storm?

131I or Radioiodine


Rx for Postmenopausal Osteoporosis?




Rx for Paget Disease to reduce bone turnover?




Rx for Hypercalcemic states?



  • Malignancy
  • Intoxication w/ Vit. D
  • Sarcoidosis
  • Hyperparathyroidism
  • Alkali (Mikl-alkali syndrome)
  • Paget Disease


Rx for Hypocalcemia?



Rx for End-Stage Renal Disease?




  • Rx for Hypothyroidism
  • Potency of each preparation varies
  • Thyroglobulin is a protein produced by thyroid cells (both normal and cancerous cells). After removal of the thyroid gland, Thyroglobulin can be used as a "cancer marker."


Sodium Liothyronine

  • Tx for Hypothyroidism
  • Short acting w/ Rapid onset
  • A synthetic form of natural T3 hormone with same actions as natural product; thyroid hormone raises basal metabolic rate, increases utilization and mobilization of glycogen store, and promotes gluconeogenesis
  • Tx: Hypothyroidism, Nontoxic goiter, Myxedema, Myxedema coma


Lugol's Solution

(KI and I2)

  • a solution of elemental iodine and potassium iodide in water
  • It was also used at one time as a first line treatment for Hyperthyroidism, as the administration of pharmacologic amounts of iodine leads to temporary inhibition of iodine organification in the thyroid gland, a phenomenon called the Wolff-Chaikoff effect.


Mechanism of PTH?

  • PTH increases plasma Ca2+
  • Stimulates adenylyl cyclase in target tissues
  • Elevated cAMP inhances syn. of 1,25(OH)2D3
  • Increasing bone resorption by activating Osteoblast --> Osteoclast and Stimulating Ca2+ transport from bone to extracellular fluids
  • Increases the synthesis of 1,25(OH)2D3 at the lvl of the Kidney
  • Increases Renal tubular reabsorption of Ca2+


Mechanism of 1,25(OH)2D3

  • 1,25 dihydroxycholecalciferol
  • 7 dehydrocholesterol is converted to Cholecalciferol (D3) by UV light at the skin
  • D3 is converted to 25(OH)D3 in the Liver
  •  25(OH)D3 converted to 1,25(OH)2D3 (calcitriol) in the Kidney
  • PTH stimulates 1α-hydroxylase, is the Kidney's converting enzyme.
  • Increases plasma Ca2+
  • Increasing the synthesis of Ca2+ binding transport protein in the Mucosal cells of the gut --> Increaseing absorption
  • Increasing Ca2+ transport from Bone to Extracellular fluids (in large doses)


Mechanism of Calcitonin?

  • Decreases plasma Ca2+
  • Decreasing bone reabsorption by inhibiting activity of osteoclasts
  • Decreasing tubular reabsortpion of Ca2+


Rx for Hypoparathyrodism?

  • Hypocalcemia
  • Hyperphosphatemia
  • Tx: Dietary calcium and 1,25(OH)2D3 
  • PTH and Calcium gluconate mabe be used following surgical parathyroidectomy to prevent Hypocalemic tetany


Rx for Pseudohypoparathyrodism?

  • PTH lvls are Normal or Elevated
  • Serum Ca2+ is low
  • End organs are insensitive to PTH
  • Often abnormal Gs, the transducer that links PTH receptor to Adenylyl cyclase
  • Tx: 1,25(OH)2D3 can correct Hypocalcemia, but it does not always improve Bone disease


Rx for Rickets and Osteomalacia?

  • Inadequate miniralization of Bone matrix
  • Lack of exposure to sunlight, resulting in impaired vitamin D3 synthesis in the skin
  • Supplementing food and Vit. D2 has greatly reduced the incidence
  • Tx: Administer Vit. D2 or D3


Rx for Vit. D-dependent Rickets?

  • Autosomal recessive does not respond to Vit. D admin.
  • Defect belived to be in the 1α-hydroxylase enzyme w/in the Kidney
  • Tx: 1,25(OH)2D3


Rx for Drug-induced Osteopenia?

  • The anticonvulsant drugs, Phenytoin, Phenobarbital, and Corticosteroids, suppress intestinal Ca2+ absorption w/ Secondary Hyperparathyroidism (elevated PTH)
  • High doses of corticosteroids inhibit Osteoblast diff. and Collagen syn. --> decreased bone mass
  • Tx: 25(OH)D3, D2, or D3 improve symptoms of Anticonvulsant-induced Osteomalacia (Osteopenia)


Rx for Paget's Disease?

  • Overactive Osteoclast activity in bone resulting in Deminieralization of Osteoid tissue
  • Painful, Multiple bone compression fractures
  • Tx: Calcitonin via Nasal spray, Sodium Etidronate (bisphosphonate), also Alendronate and Risedronate, and even Ibandronate.


Rx for Postmenopausal Osteoporosis?

  • Abnormal, rapid loss of bone, predisposing postmenopausal women to Fracture
  • Tx: Estrogen replacement therapy w/ increased risk of Heart disease, Breast cancer, and Uterine cancer w/ HRT
    • SERM - Raloxifene is safer
  • Bisphosphonates: Alendronate, Risedronate, Ibandromate, or Zoledronic acid
  • Teriparatide (Human PTH1-34) is effective for treating osteoporosis --> stimulates new bone growth and reduces vertebral fracture risk by 65%, injected daily


Rx for Vitamin D intoxication?

  • Hypercalcemia leading to Ca2+ deposition in soft tissues
  • Tx: Stop Vit. D administration, Administer Glucocorticoids, such as Prednisone --> Block GI absorption of Ca2+


Rx Primary Hyperparathyroidism?

  • Commonly Adenoma
  • Severe Hypercalcemia, Hypophosphatemia, Prominent bone resoprtion, Soft Tissue calcification, Elevated 1,25(OH)2D3 and Nephrolithiasis
  • Tx: Surgical removal of Adenoma