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Parathyroid Glands

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Called parathyroid glands because of their position ... causing increased production of PTH Secondary Hyperparathyroidism Defect in mineral homeostasis leading to ... – PowerPoint PPT presentation

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Title: Parathyroid Glands


1
Parathyroid Glands
  • HUSSEN.S.ALNAKHLY

2
  • PARATHYROID GLAND
  • Location
  • Usually paired.
  • Very small (less than 5 mm).
  • Called parathyroid glands because of their
    position on posterior margins outer surface of
    thyroid gland.
  • More superior of each pair usually near middle of
    margin of lobe.
  • More inferior of each pair usually at inferior
    apex of lobe.
  • Development Like thyroid gland, develop from
    endodermal thickening in floor of early pharynx
    and epithelium of 3rd and 4th gill slit pouches.

3
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4
Anatomy
  • Arterial supply usually from inferior thyroid art
  • Superior glands usually imbedded in fat on
    posterior surface of middle or upper portion of
    thyroid lobe
  • Lower glands near the lower pole of thyroid gland
  • In 1-5 pts, inferior gland in deep mediastinum

5
Histology
  • 50/50 parenchymal cells, stromal fat
  • Chief cells secrete PTH
  • Waterclear cells
  • Oxyphil cells

6
Parathyroid Hormone
  • Synthesized in chief cells as large precursor
    pre-proparathyroid hormone
  • Cleaved intracellularly into proparathyroid
    hormone then to final 84 AA PTH
  • PTH then metabolized by liver into hormonally
    active N-term and inactive C-term

7
PTH function
8
Hyperparathyroidism
  • Primary Hyperparathyroidism
  • Normal feedback of Ca disturbed, causing
    increased production of PTH
  • Secondary Hyperparathyroidism
  • Defect in mineral homeostasis leading to a
    compensatory increase in parathyroid gland
    function

9
Etiology
  • Unknown cause
  • Single gland adenomatous disease
  • Multiglandular disease exogenous stimulus
  • Ionizing radiation exposure

10
Clinical Presentation
  • Nephrolithiasis
  • Bone Disease
  • Peptic Ulcer Disease
  • Psychiatric disorders
  • Muscle weakness
  • Constipation
  • Polyuria
  • Pancreatitis
  • Myalgia
  • Arthralgia

11
Hypercalcemia
  • Hyperparathyroidism (most common)
  • Malignancy (most common in hospitalized)
  • Lytic metastases to bone
  • PTHrP producer
  • Sarcoidosis / granulomatous disease
  • Vit D intoxication
  • Thiazides
  • Hyperthyroidism
  • Familial hypocalciuric hypercalcemia

12
Renal Complications
  • Generally the most severe clinical manifestations
  • Many have frequency, polyuria, polydipsia
  • Usually present w/ nephrolithiasis (20-30)
  • Calcium phosphate or Calcium oxalate
  • Nephrocalcinosis (in 5-10) calcification w/in
    parenchyma of kidneys
  • Severe renal damage
  • Hypertension secondary to renal impairment

13
Bone Disease
  • Osteitis fibrosa cystica
  • In early descripts of disease, many had severe
    bone disease (50-90), but now 5-15
  • Subperiosteal resorption pathognomonic of
    hyperparathyroidism

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16
Gastrointestinal Manifestations
  • Peptic Ulcer disease
  • Pancreatitis
  • Cholelithiasis 25-35

17
Neuromuscular complications
  • Muscular weakness, fatigue
  • More commonly in proximal muscles
  • Sensory abnormalities also possible

18
Laboratory Diagnosis
  • Elevated Serum Ca and PTH
  • Must measure Ionized Ca (subtle cases of hyperPTH
    will have normal Serum Ca)
  • 50 will have hypophosphatemia Elevated Alkaline
    Phosphatase in 10-40
  • Hyperchloremic metabolic acidosis
  • Low Mg in 5-10
  • High Urinary Ca in almost all cases
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