parathyroid Flashcards
avg weight 1 parathyroid gland
25-50 mg
color of normal parathyroid
yellow
red brown parathryoid gland
adenoma
2 cell types in parathyroid gland
chief cells and oxyphil cells
why are oxyphil cells pink
lots of mitochondria
function of parathyroid gland
regulate calcium homeostasis
how do PTH glands regulate Ca
icnrease renal tubular resorption of Ca
increase conversion of Vit D to active form in kidneys
increase urinary PO4 lowering serum PO4
change GI Ca absorption
what is primary hyperPTH
autonomous overproduction of PTH usually resulting from adenoma or hyperplasia of PTH tissue
what is secondary hyper PTH
compensatory hypersecretion of OTH in response to prolonged hypoCa, usually from chronic renal failure
what is tertiary hyper PTH
persistent hypersecretion of PTH even after the cause of prolonged hypoCa is corrected
(e.g after renal transplant)
3 most common causes of primary hyper PTH
pituitary adenoma
primary hyperplasia (diffuse or nodular)
PTH carcinoma
microscopic PTH adenoma
uniform polygonal chief cells with small central nuclei
what type of PTH adenoma resemble hurthle cell changes
oxyphil adenomas
what is endocrine atypia
pleomorphic nuclei in adenomas
histo of PTH adenoma
no fat, thin rim of normal PTH (has fat globules)
most common cause primary hyeprPTH
solitary PTH adenoma arising sporadically
how is hyper PTH detected usually
first incidental finding of hyeprCa
genetic syndromes assoc with familial PTH adenomas
MEN 1 and 2
germline mutations in MEN1 and RET
bone Sx of hyperPTH
osteoporosis, brown tumors, osteitis fibrosa cystica
osteoclasts in hyperPTH affect what bone type more than medullary bone
cortical (subperiosteal and endosteal surfaces)
what is dissecting osteitis
when osteoclasts in medullary bone dissect centrally along the trabeculae creating appearance of railroad tracks
What is osteitis fibrosa cystica
von Recklinghausen disease of bone
increased osteoclast activty, peritrabecular fibrosis and cystic brownt tumors
what is a cystic brown tumor in bone from
loss of bone causes microfractures, hemorrhage and influx of macrophages that cause reparative fibrous tissue and reactive tissue i.e. brown tumor
how does hyper PTH affect renal system
nephrolithiasis and nephrocalcinosis
met calcification can occur in stomach lungs myocardium and blood from hyperCa
most common cause asymptomatic hyper Ca
primary hyperPTH
cause of symptomatic hyperCa in adults
malignancy: solid tumors like lung, breast, head and neck and renal cancers
multiple myeloma
mech in which osteolytic tumors induce hyperCa
secretion of PTH related peptide PTHrP
Causes of hyper Ca with decreased PTH levels too
hyperCa of malignancy Vit D toxicity immobilization thiazide diuretics granulomatous disease (sarcoidosis)
painful bones, renal stones, abdominal groans and psychic moans
primary hyperPTH
Abdominal Sx from primary hyper PTH
nausea, vomiting, constipation, indigestion
effects of hyperPTH on nervous system
lethargy, fatigue, memory loss, psychosis, depression
most common cause secondary hyper PTH
renal failure
what occurs in secondary hyper PTH
chronic hypocalcemia that leads to compensatory overactivity of the PTH glands
kimmelstein wilson glomeruli
DM and nodular glomerulosclerosis
what other diseases can cause secondary hyper PTH
inadequate dietary intake of Ca, steatorrhea, vit D deficiency
morphology of PTH glands d/t secondary hyperPTH
all 4 glands enlarged
hyperplastic with increased chief cells and abundant clear cytoplasm
fat cells are decreased in number
secondary hyperPTH has met calcificaitons where
lungs, heart stomach and blood vessels
what is calicphylaxis
vascular calcification assoc with secondary hyper PTH from ischemic damage to skin and other organs
what do you Tx patients with secondary hyperPTH
dietary vit D supp
phosphate binders which dec the hyperphosphatemia
what is tertiary hyperPTH
autonomous and excessive with resultant hyperCa
Tx tertiary hyperPTH
parathyroidectomy
acquire hypoPTH is usually a consequence of
surgery
PTH glands are mistaken for what
lymph nodes
what is autoimmune hypoPTH
chronic mucocutaneous candidiasis and primary adrenal insufficiency
autoimmune polyendocrine syndrome type 1
what mutations cause autoimmune polyendocrine syndrome type 1
autoimmune regulator gene
how does autoimmune hypoPTH present
candidiasis in childhoos followed by hypoPTH and adrenal insufficiency in adolescence
what is autosomal dominant hypoPTH caused by
gain of function mutations in Ca sensing R gene
results in hypocalcemia and hypercaliuria
What is familial isolated hypoPTH
FIH rare condition with auto dom or auto recessive patterns
What causes auto dom FIH (familial isolated hypoPTH)
mutation in gene encoding PTH precursor peptide which impairs its processing to the mature hormone
What causes auto recessive FIH(familial isolated hypoPTH)
loss of function mutations in transcription factor gene glial-cells-missing-2 GCM2 which is needed for development of parathyroid
what can cause congenital absence of PTH glands
thymic aplasia, CV defects
22q11 deletion syndrome(digeorge)
hallmark clinical features hypoPTH
tetany with neuromuscular irritability (Decreased serum Ca levels)
circumoral numbness, parasthesias of distal extremities and carpopedal spasm to life threatening laryngospasm and generalized seizures
What is a Chvostek sign
tap along facial nerve to induce contractions of the muscles of the eye mouth or nose
What is a Trousseau sign
carpal spasms produced by occlusion of the circulation to the forearm and hand with a bp cuff for several minutes
other clinical features to hypoPTH
mental status changes like emotional instability and anxiety
intracranial manifestations like calcifications of basal ganglia
ocular- calcification of lens and cataract
CV manifestations- long QT
dental- dental hypoplasia, failure eruption, defective enamel and root formation
what causes the intracranial manifestations of hypoPTH
increased phosphate levels resulting in tissue deposits with Ca that exists in local extracellular milieu
what causes pseudohypoPTH
end-organ Resistance to the actions of PTH
how does pseudohypoPTH present
hypoCa, hyperphosphatemia, elevated circulating PTH
signs of pseudohypoPTH
+chvosteks and trousseaus
short stature and short fingers
increased PTH
mental retardation
