Flashcards in Parathyroid Deck (37)
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?
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?
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?
- Bone metabolism
What is increased in Hyperparathyroidism? and what does that lead to?
- Leads to Hypercalcemia and Hypophosphatemia
More than half the pts that are diagnosed with Hyperparathyroidism are what?
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?
- Anorexia/wt loss
- Abdominal pain
- Peptic Ulcer
- 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?
(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?
Aside from the MCC what are the other causes of hypoparathyroidism?
- Autoimmune Disease
- Hypomagnesemia (Chronic Alcoholic)
- Heavy Metal Toxicity (Wilson Disease, Hemochromatosis)
A common clinical presentations of hypoparathyroidism is hypoclacemia, what are 2 signs used to confirm hypocalcemia?
- Chvostek's Sign: Tapping on the facial nerve causes contraction of eye, mouth, or nose muscles
- Trousseau Sign: Inflated BP cuff causes a hand & wrist spasm
What are some physical presentations of hypoparathyroidism?
- Dry skin/birttle Nails
- MS cramping
- Paresthesias in extremities
- Hyperactive DTR
What are some cardiovascular sxs caused by hypoparathyroidism?
What are the serum diagnostic findings for hypoparathyroidism?
- PTH: ↓
- Adjusted Serum Calcium: ↓
- Phosphate: ↑
- Magnesium: May be ↓ (Hypomagnesemia may worsen symptoms)