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
(No Transcript)
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

14
(No Transcript)
15
(No Transcript)
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