Parathyroid: Guerin Flashcards
parathyroid histology: chief cells
central, round, uniform nuclei
light pink cytoplasm, can be clear from glycogen
secretory granules of PTH
parathyroid histology: oxyphil cells
slightly larger than chief cells
acidophilic cytoplasm
tightly packed with mitochondria
causes of hypercalcemia with decreased PTH
1) hypercalcemia of malignancy
2) vitamin D tox
3) immobilization
thiazide diuretics
granulomatous disease (sarcoidosis)
causes of hypercalcemia with raised PTH
hyperparathyroidism
1) primary (adenoma > hyperplasia)
2) secondary, compensatory hypersecretion PTH due to prolonged hypocalcemia, chronic renal failure
3) tertiary, hyper PTH even after prolonged hypocalcemia corrected like after renal transplant
familial hypocalciuric hypercalcemia
two molecular defects play a role in sporadic parathyroid adenoma
cyclin D1 gene inversions
MEN1 mutations
familial syndromes with parathyroid adenoma
MEN type 1 and 2: MEN 1 and RET mutation
familial hypocalciuric hypercalcemia
- rare AD disorder
- mutation in CASR
morphology of adenoma
*****solitary
0.5-5gm
well circumscribed
glands outside adenoma usually normal in size or shrunken
hypercellular with little to no fat
uniform chief cells
few nests of larger oxyphil cells
rim of compressed parathyroid gland, generally separated by fibrous capsule
parathyroid hyperplasia occurs
sporadically or as component of mEN
parathyroid hyperplasia
glands involved
combined weight
classically all 4 glands***
combined weight of all glands is rarely over 1 gm
parathyroid carcinoma
rare
need invasion of surrounding tissues and or metastaiss for dx
what can be used to visualize parathyroid ademoma
sestamibi scan
skeletal system pathology from increased PTH
osteoporosis
brown tumors: microfracture and secondary hemorrhages, brown from vascularity, hemorrhage, hemosiderin deposition
osteitis fibrosa cystica (severe hyper PT, rare)
-increased osteoclast activity, peritranecular fibrosis, and cystic brown tumors
other organ pathology of hyper PTH besides bone
nephrolithiasis (urinary tract stones)
nephrocalcinosis
- calcification of renal interstitium and tubules
- can be seen in stomach, lungs, myocardium and BVs
the most common cause of symptomatic hypercalcemia
malignancy
what malignancies in hypercalcemia of malignancy
multiple myeloma
solid tumors
-lung, breast, head and neck, renal
symptoms of primary hyperparathyroidism
bones
stones
abdominal groans
psychic moans
neuromuscular wekness and fatigue
cardiac: aortic and or mitral valve calcifications
symptoms of primary hyperparathyroidism: renal
nephrolithiasis
- pain and obstructive uropathy
- chronic renal insufficiency and abnormalities in renal function: polyuria and secondary polydipsia
secdonary hyperparathyroidism is usually from
renal failure
also inadequate dietary intake of calcium, steatorrhea, and vitamin D deficiency
morphology of secondary hyperparathyroidism
hyperplastic parathryoid glands (decreased fat)
-can be asymmetric
increased number of chief cells
-diffuse or multinodular
metastatic calcifications can be seen in lungs, heart, stomach, and BVs
clinical course of secondary hyperparathyroidism
treatment
calciphylaxis: vascular calcification–> ischemic damage to skin and other organs
tx: vitamin D supplements and phosphate binders
tertiary hyperparathyroidism
treatment
occasionally in pts with secdonary hyperparathyroidism
parathyroids become autonomous and excessive (function independently after chronic renal failure and stimulation)
tx: remove parathyroids
hypoparathyroidism causes
surgically induced from a thyroidectomy (accidental removal)
autoimmune: assocaited with chronic mucocutaneous candidiasis and primary adrenal insufficiency (APS1)
autosomal dominant hypoparathyroidism
-GOF in CASR
familial isolated hypoparathyroidism
congenital absence of glands (digeorge)
signs of hypocalcemia
tetany (tingling of distal extremtiies)
-when severe can have life threat laryngospasm and seizures
chvostek sign
trousseau sign
mental status changes: emotional instability, anxiety, depression, confucion, hallucination, psychosis
clincial manifestations of hypocalcemia
paradoxical calcifications (likely from increased phosphate levels)
- basal ganglia–> parkinsonian-like movement disorder
- lens and cataract formation
heart: conduction defect: pronlonged QT on ECG
dental abnormalities when hypocalcemia present during early development
pseudohypoparathyroidism
cause
PTH levels
presents as what lab levels
also resitance to what bc of what
end organ resistance to PTH
serum PTH levels normal or elevated
presents as hypocalcemia and hyperphosphatemia
can also have end organ resitance to pTH, TSH and FSH/LH
-from genetic defects in GPCR
