Parathyroid Flashcards
(37 cards)
Where is the parathyroid gland located?
4 glands located posterior to the thyroid gland
What does the parathyroid gland produce?
Parathyroid hormone (PTH)
PTH is the primary regulator of what?
Calcium Physiology
PTH directly acts on what?
- Bone: stimulates Ca2+ release
- Kidneys: enhances Ca2+ reabsorption in the proximal and distal tubules and synthesizes 1, 25 dihydroxyvitamin D- a hormone
PTH indirectly acts on what?
GI tract: increases Ca2+ reabsoprtion
Serum PTH levels are tightly regulated by what?
Negative feedback loop
In the negative feedback loop calcium is acting on what receptor?
Calcium-sensing receptor (CaR) located on the chief cells of the parathyroid glands
In the negative feedback loop Vitamin D is acting on what receptor?
Nuclear receptor
High levels of Calcium and Vitamin D reduces what?
PTH release and synthesis
What is the feedback loop for hypocalcemia?
- Parathyroid gland: detects low Ca2+
- Increased PTH release
- Increases rate of dissolution of bone material and increases Ca2+
- Reduced renal clearance of Ca2+
- Increases Ca2+ reabsorption in GI tract
What is the feedback loop for hypercalcemia?
- Parathyroid gland: detects high Ca2+
- Decreased PTH release
- Decreases rate of dissolution of bone material and decreases Ca2+
- Increased renal clearance of Ca2+
- Decreases Ca2+ reabsorption in GI tract
Hyperparathyroidism is a disorder of what?
- Calcium
- Phosphate
- Bone metabolism
What is increased in Hyperparathyroidism? and what does that lead to?
- PTH
- Leads to Hypercalcemia and Hypophosphatemia
More than half the pts that are diagnosed with Hyperparathyroidism are what?
Asymptomatic
What are some causes of Hyperparathyroidism?
- Benign Neoplasm or Adenoma Secreting PTH
- Carcinoma or Parathyroid Hyperplasia (Very Rare)
- MEN: Multiple Endocrine Neoplasm
- Lithium Therapy
- Familial Hypocalciuric Hypercalcemia (FHH)
Hyperparathyroidism manifests primarily in the bones and kidneys, what can that cause?
- Bone: Osteitis Fibrosa Cystica
(where bone tissue becomes soft and deformed, can be painful) - Kidney: Nephrocalcinosis or Recurrent Nephrolithiasis
What are the clinical presentations of Hyperparathyroidism?
- Thirst
- Anorexia/wt loss
- N/V
- Abdominal pain
- Peptic Ulcer
- Pancreatitis
- Constipation
- Fatigue
- Anemia
- HTN
- Depressed reflexes
Summary of sxs of Hyperparathyroidism can be remembered by STONES, BONES, GROANS, and MOANS, what does each represent?
STONES - Renal: Loss of Calcium & Phosphate
BONES: Pain- Diffuse Bone Demineralization, Trabecular Bone Increase
GROANS: Increased GI Absorption & Abdominal Cramps
MOANS: Irritability & Depression
What are the CMP diagnostic findings for Hyperparathyroidism?
- Ca2+: ↑ (2 measurements required to confirm)
- Phosphate: Normal to ↓
What are the PTH diagnostic findings for Hyperparathyroidism?
↑PTH
If low, when calcium is high, possible malignancy
What are the ECG diagnostic findings for Hyperparathyroidism?
- Prolonged PR Interval
- Shortened QT Interval
- Bradycardia or Heart Block
What are the 24 Hr. Urine Calcium and Creatinine diagnostic findings for Hyperparathyroidism?
- Calcium is ↓ for the degree of hypercalcemia
- Creat. Clearance to assess the kidney functions
What are the bone density diagnostic findings for Hyperparathyroidism?
Osteopenia or Osteoporosis
What is the MCC of acquired hypoparathyroidism?
Parathyroidectomy
