Surgical diseases of the parathyroid glandPresentation Transcript
SURGICAL DISEASES OF THE PARATHYROID GLANDS
Anatomy / Embryology and Physiology
Four parathyroid glands – 2 superior and 2 inferior glands
Flat, ovoid and red-brown to yellow
3 x 3 x 3 mm
30 – 50 mg
Inferior thyroid artery – main blood supply
4th – 5th weeks of fetal life – pharyngeal pouches developed
4th pouch + lateral thyroid anlage = superior gland
3rd pouch + thymus = inferior gland
Primary Function is the ENDOCRINE REGULATION OF CALCIUM AND PHOSPHATE METABOLISM. Hormonal Regulation of Calcium and Phosphate metabolism Parathyroid Hormone Vitamin D Calcitonin Gastrointestinal tract No direct effect Stimulates calcium and phosphate absorption No direct effect Skeleton Stimulates calcium and phosphate resorption Stimulates calcium and phosphate transport Inhibits calcium and phosphate resorption Kidneys Stimulates calcium resorption Inhibits phosphate resorption No direct effect Inhibits calcium and phosphate resorption
Feedback loops involved in the regulation of serum calcium and phosphorus (PTH – parathyroid hormone; CT-calcitonin)
Inappropriately increased amounts of parathyroid hormone (PTH) relative to the serum calcium level
Occurs in 1:1000 population
Increased detection due to increase use of serum calcium determination
Three histologic pattern:
Three histologic patterns are seen: (primary hyperparthyroidism)
90% of cases
A rim of normal parathyroid tissue around the adenoma distinguishes adenoma from hyperplasia
10% of cases.
No rim of normal parathyroid tissue and lack of stromal fats
All 4 glands are involved.
The hyperparathyroidism of MEN syndromes is due to hyperplasia.
Parathyroid carcinoma - <1% of cases.
Exceptionally high calcium or palpable neck mass should raise suspicion.
Excision with thyroid lobectomy is indicated.
Radical neck dissection for recurrent disease. Recur locally 30%; distant metastasis to lung liver and bone in 30%.
Hypocalcemia is common and occurs almost immediately.
Monitor serum calcium
Symptoms – anxiety, hyperventilation, Chvostek’s and Trousseau’s signs, acral and circumoral paresthesias.
Some advocate treating only symptomatic hypocalcemia.
Treat hypocalcemia with oral calcium carbonate 1 g PO q6h, or IV calcium gluconate for severe hypocalcemia (< 7.0).
Vitamin D supplementation may be necessary for refractory hypocalcemia
Watch out for bleeding and infection
Hyperparathyroidism secondary to malfunction of another organ system
Usually occurs in patients with chronic renal failure, but may also be due to osteogenesis imperfecta, Paget’s disease, or multiple myeloma
Pathophysiology in renal failure
Increased phosphate because of poor renal excretion Decreased serum calcium, decreased gut absorption of calcium due to decreased renal 1-hydroxylation of vitamin D2 and decreased renal clearance of PTH breakdown products.
Clinically manifests as psychiatric disorders, headache, muscle weakness, weight loss, fatigue, renal osteodystrophy (bone resorption with pathologic fractures) and soft tissue calcifications (vessels, tendons and joint sheaths)
Treatment is directed at underlying disorder – phosphate-binding antacids, oral calcium and vitamin D, increased calcium dialysate for chronic renal insufficiency patients.
Surgery is indicated for uncontrolled symptoms – either 3-½-gland parathyroidectomy or 4-gland parathyroidectomy with implantation of minced glands into sternocleidomastoid or forearm muscles marked by a surgical clip.
Persistent hyperparathyroidism and hypercalcemia following successful renal transplant or resolution of underlying disorder
Up to 30% of patients who have pre-transplant hyperparathyroidism Pathophysiology is irreversible
Parathyroid gland hyperplasia with autonomous PTH production.
Surgery is indicated for symptomatic patients or patients unresponsive to medical management 6 months post - transplant – either 3 ½ gland parathyroidectomy with implantation of minced glands into muscle.