Parathyroid Glands

2,309 views
2,006 views

Published on

0 Comments
4 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
2,309
On SlideShare
0
From Embeds
0
Number of Embeds
17
Actions
Shares
0
Downloads
226
Comments
0
Likes
4
Embeds 0
No embeds

No notes for slide

Parathyroid Glands

  1. 1. Parathyroid Glands Scott Nguyen Dr. Lopchinsky
  2. 2. Embryology <ul><li>Branchial arches and Pharyngeal pouches form in the 4 th week </li></ul><ul><li>Superior Parathyroids - the 4 th Pharyngeal pouch w/ thyroid </li></ul><ul><li>Inferior Parathyroids – 3 rd Pharyngeal pouch </li></ul><ul><li>w/ thymus </li></ul>
  3. 4. Anatomy <ul><li>Arterial supply usually from inferior thyroid art </li></ul><ul><li>Superior glands usually imbedded in fat on posterior surface of middle or upper portion of thyroid lobe </li></ul><ul><li>Lower glands near the lower pole of thyroid gland </li></ul><ul><li>In 1-5% pts, inferior gland in deep mediastinum </li></ul>
  4. 5. Histology <ul><li>50/50 parenchymal cells, stromal fat </li></ul><ul><li>Chief cells – secrete PTH </li></ul><ul><li>Waterclear cells </li></ul><ul><li>Oxyphil cells </li></ul>
  5. 6. Parathyroid Hormone <ul><li>Synthesized in chief cells as large precursor – pre-proparathyroid hormone </li></ul><ul><li>Cleaved intracellularly into proparathyroid hormone then to final 84 AA PTH </li></ul><ul><li>PTH then metabolized by liver into hormonally active N-term and inactive C-term </li></ul>
  6. 7. PTH function
  7. 8. Hyperparathyroidism <ul><li>Primary Hyperparathyroidism </li></ul><ul><ul><li>Normal feedback of Ca disturbed, causing increased production of PTH </li></ul></ul><ul><li>Secondary Hyperparathyroidism </li></ul><ul><ul><li>Defect in mineral homeostasis leading to a compensatory increase in parathyroid gland function </li></ul></ul><ul><li>Tertiary Hyperparathyroidism </li></ul><ul><ul><li>After prolonged compensatory stimulation, hyperplastic gland develops autonomous function </li></ul></ul>
  8. 9. Primary Hyperparathyroidism <ul><li>Epidemiology </li></ul><ul><li>25/100,000 </li></ul><ul><li>50,000 new cases yearly </li></ul><ul><li>F > M </li></ul><ul><li>Incidence increases w/ age </li></ul><ul><li>Most in > 50 years old </li></ul>
  9. 10. Etiology <ul><li>Unknown cause </li></ul><ul><li>Single gland adenomatous disease </li></ul><ul><li>Multiglandular disease – exogenous stimulus </li></ul><ul><li>Overexpression of PRAD1 oncogene – controlls cell cycle </li></ul><ul><li>Ionizing radiation exposure </li></ul>
  10. 11. Clinical Presentation <ul><li>Nephrolithiasis </li></ul><ul><li>Bone Disease </li></ul><ul><li>Peptic Ulcer Disease </li></ul><ul><li>Psychiatric disorders </li></ul><ul><li>Muscle weakness </li></ul><ul><li>Constipation </li></ul><ul><li>Polyuria </li></ul><ul><li>Pancreatitis </li></ul><ul><li>Myalgia </li></ul><ul><li>Arthralgia </li></ul><ul><li>30 </li></ul><ul><li>2 </li></ul><ul><li>12 </li></ul><ul><li>15 </li></ul><ul><li>70 </li></ul><ul><li>32 </li></ul><ul><li>28 </li></ul><ul><li>1 </li></ul><ul><li>54 </li></ul><ul><li>54 </li></ul>
  11. 12. Hypercalcemia - DDx <ul><li>Hyperparathyroidism (most common) </li></ul><ul><li>Malignancy (most common in hospitalized) </li></ul><ul><ul><li>Lytic metastases to bone </li></ul></ul><ul><ul><li>PTHrP producer </li></ul></ul><ul><li>Sarcoidosis / granulomatous disease </li></ul><ul><li>Vit D intoxication </li></ul><ul><li>Thiazides </li></ul><ul><li>Hyperthyroidism </li></ul><ul><li>Familial hypocalciuric hypercalcemia </li></ul>
  12. 13. Renal Complications <ul><li>Generally the most severe clinical manifestations </li></ul><ul><li>Many have frequency, polyuria, polydipsia </li></ul><ul><li>Usually present w/ nephrolithiasis (20-30%) </li></ul><ul><li>Calcium phosphate or Calcium oxalate </li></ul><ul><li>Nephrocalcinosis (in 5-10%) – calcification w/in parenchyma of kidneys </li></ul><ul><ul><li>Severe renal damage </li></ul></ul><ul><li>Hypertension secondary to renal impairment </li></ul>
  13. 14. Bone Disease <ul><li>Osteitis fibrosa cystica </li></ul><ul><li>In early descripts of disease, many had severe bone disease (50-90%), but now 5-15% </li></ul><ul><li>Subperiosteal resorption – pathognomonic of hyperparathyroidism </li></ul>
  14. 17. Gastrointestinal Manifestations <ul><li>Peptic Ulcer disease </li></ul><ul><li>Pancreatitis </li></ul><ul><li>Cholelithiasis – 25-35% </li></ul>
  15. 18. Emotional Disturbances <ul><li>Hypercalcemia of any cause – assoc w/ neurologic or psychiatric disturbances </li></ul><ul><ul><li>Depression, anxiety, psychosis, coma </li></ul></ul><ul><li>Severe disturbances not usually correctable by parathyroidectomy </li></ul>
  16. 19. Articular and Soft Tissue <ul><li>Chondrocalcinosis and Pseudogout 3-7% </li></ul><ul><li>Deposits of Calcium pyrophosphate in articular cartilages and menisci </li></ul><ul><li>Vascular and Cardiac calcifications </li></ul>
  17. 20. Neuromuscular complications <ul><li>Muscular weakness, fatigue </li></ul><ul><li>More commonly in proximal muscles </li></ul><ul><li>Sensory abnormalities also possible </li></ul>
  18. 21. Laboratory Diagnosis <ul><li>Elevated Serum Ca and PTH </li></ul><ul><ul><li>Must measure Ionized Ca (subtle cases of hyperPTH will have normal Serum Ca) </li></ul></ul><ul><li>50% will have hypophosphatemia Elevated Alkaline Phosphatase in 10-40% </li></ul><ul><li>Hyperchloremic metabolic acidosis </li></ul><ul><li>Low Mg in 5-10% </li></ul><ul><li>High Urinary Ca in almost all cases </li></ul>
  19. 22. Hyperparathyroid crisis <ul><li>Most pts w/ hyperparathyroidism chronically ill w/ renal and skeletal abnormalities </li></ul><ul><li>Rarely can become acutely ill </li></ul><ul><li>Rapidly developing weakness, N/V, weight loss, fatigue, drowsiness, confusion, Azotemia </li></ul><ul><li>Uncontrolled PTH production, hyperCa, polyuria, dehydration, reduced renal function, worsening hyperCa </li></ul>
  20. 23. Hyperparathyroid Crisis <ul><li>Definitive therapy - resection </li></ul><ul><li>Must reverse hyperCa first </li></ul><ul><ul><li>Diuresis - Saline hydration then Lasix to excrete Ca </li></ul></ul><ul><ul><li>Calcitonin - rapid affect, inhibits bone resorption </li></ul></ul><ul><ul><li>Steroids - take up to a week </li></ul></ul><ul><ul><li>Mithramycin - rapidly inhibiting bone resorption </li></ul></ul>
  21. 24. Treatment <ul><li>Only Curative treatment - Parathyroidectomy </li></ul><ul><li>Who should have surgery? </li></ul><ul><ul><li>Many found incidentally, assx </li></ul></ul>
  22. 25. Who should have surgery? <ul><li>NIH Consensus statement 1991 </li></ul><ul><li>All symptomatic </li></ul><ul><li>If Assymptomatic </li></ul><ul><ul><li>Markedly elevated serum Ca </li></ul></ul><ul><ul><li>H/o episode life-threatening hypercalcemia </li></ul></ul><ul><ul><li>Reduce renal function </li></ul></ul><ul><ul><li>Kidney stone on Radiograph </li></ul></ul><ul><ul><li>Markedly elevated urinary Ca excretion </li></ul></ul><ul><ul><li>Substantially reduce bone mass </li></ul></ul>
  23. 26. Standard Neck Exploration
  24. 27. Parathyroidectomy <ul><li>Must find all four glands </li></ul><ul><li>Intraoperative frozen section, PTH measurement useful </li></ul><ul><li>If single gland enlarged, removal usually curative </li></ul><ul><li>If multiple glands enlarged, removed. Normal just biopsied </li></ul><ul><li>If all 4 enlarged (generalized parathyroid hyperplasia) - subtotal (3 1/2 removed) </li></ul><ul><ul><li>Can reimplant into forearm muscle </li></ul></ul>
  25. 28. <ul><li>Superior parathyroid </li></ul><ul><li>easier to find </li></ul><ul><li>more consistent position </li></ul><ul><li>just on dorsal surface of upper thyroid </li></ul><ul><li>careful for superior thyroid artery and superior laryngeal nerve </li></ul>
  26. 29. <ul><li>Inferior gland </li></ul><ul><li>less consistent location </li></ul><ul><li>may be near thymus or inside thyroid </li></ul><ul><li>careful for recurrent laryngeal nerve betw trachea / esophagus </li></ul><ul><li>inferior thyroid artery </li></ul>
  27. 31. Success of Surgery <ul><li>95% of cases cured at initial neck exploration </li></ul><ul><li>If failed intial procedure, can try to localize w/ Radionuclide, detect w/ gamma probe </li></ul><ul><ul><li>Sestamibi concentrates in parathyroid tissue </li></ul></ul><ul><ul><li>Increasingly used in initial operation </li></ul></ul><ul><ul><li>limits dissection </li></ul></ul><ul><ul><li>Limits operative time </li></ul></ul><ul><li>May need mediastinoscopy </li></ul>

×