ABSITE Review - Parathyroid Flashcards
What pouch does the superior and inferior parathyroid originate from?
Superior parathyroids - 4th pouch
Inferior parathyroids - 3rd pouch
What is the relation of the superior and inferior parathyroid glands to the RLN?
Superior parathyroids - Lateral to RLN, above inferior thyroid artery
Inferior parathyroids - Medial to RLN, more anterior, below inferior thyroid artery
What is the MC ectopic site for the inferior parathyroid glands?
Tail of the thymus
What is the MCC of hypoparathyroidism?
Previous thyroid surgery
What is the oncogen that increases the risk of parathyroid adenomas?
PRAD-1
How is hyperparathyroidism diagnosed?
High Ca, Low Phos, Cl:Phos ratio >33, high renal, high renal cAMP, HCO3- secreted in urine
What metabolic disturbance is seen in primary hyperparathyroidism?
Hyperchloremic metabolic acidosis
What is the name of the bone lesions from Ca resorption?
Osteitis fibrosa cystica (brown tumors)
What are the indications for surgery in Primary Hyperparathyroidism?
Symptomatic disease or asymptomatic disease with Ca >13, low Cr clearance, kidney stones, substantially low bone mass
What is the MCC of Primary Hyperparathyroidism?
Single adenoma in 80% patients
How the intraop PTH works?
Can help determine if the causative gland is removed (PTH should go to <50% of the preop value); PTH half life is 10 minutes
If you cannot find a parathyroid gland, what is the next step?
Check inferiorly in thymus tissue ( MC ectopic location), near carotids, vertebral body, superior to pharynx, thyroid
If you can still find the gland, what is the next step?
Intraop ultrasound
Close and follow PTH, if PTH still high, get parathyroid scan to localize
What is the cause of postop hypocalcemia?
Caused by bone hunger, hypoMg, failure of parathyroid remnant or graft
What is the utility of the sestamibi-technetium scan-99?
Good for picking up adenomas but not 4-gland hyperplasia
Best for trying to pick up ectopic glands
In which patients, is secondary hyperparathyroidism usually seen?
Renal failure patients
What are the laboratory findings of 2ary Hyperparathyroidism?
Increase PTH in response to low Ca
What is the treatment of 2ary Hyperparathyroidism?
Control diet phosphurus, PO4-binding gel, decrease aluminum, Ca supplement, vitamin D, Ca in dialysate
What is the MC indication for surgery in 2ary hyperparathyroidism?
Bone pain
Others - fractures, or pruritus
What is tertiary hyperparathyroidism?
Renal disease corrected with transplant but still overproduces PTH
What is the surgery of choice for 2ary and 3ary hyperparathyroidism?
Subtotal (3.5 glands) or total parathyroidectomy with autotransplantation
What lab findings are seen in familial hypercalcemic hypocalciuria
Increase serum calcium and low urine calcium
What is the cause of familial hypercalcemic hypocalciuria?
Caused by defect in PTH receptor in distal convoluted tubule of the kidney that causes increase resorption of calcium
In parathyroid cancer, what is the preferred surgery?
Wide en bloc excision (parathyroidectomy and ipsilateral thyroidectomy)
What is the inheritance of MEN syndrome?
Autosomal dominant
What are the classic findings of MEN I?
Parathyroid hyperplasia - usually 1st symptoms
Pancreatic islet cell tumors - Gastrinoma #1, 50% multiple, 50% malignant
Pituitary adenoma - Prolactinoma #1
What are the classic findings of MEN IIa?
Parathyroid hyperplasia
Pheochromocytoma - often bilateral, almost always benign
Medullary thyroid carcinoma - often bilateral, #1 cause of death
CORRECT pheochromocytoma first
What are the classic findings of MEN IIb?
Pheochromocytoma - often bilateral, almost always benign
Medullary thyroid carcinoma - often bilateral, #1 cause of death
Mucosal Neuromas
Marfan’s habitus, MSK abnormalities
CORRECT pheochromocytoma first
What is the gene and chromosome of MEN I?
MENIN gene in Ch 11
What is the gene and chromosome of MEN II?
RET proto-oncogene in Ch 10
