Parathyroid Flashcards
What regulates calcium in the body?
- PTH
- calcitonin
- active vitamin D
What body systems utilize calcium?
- nervous
- muscular
- skeletal
Where is most of the body’s calcium stored
in the bones (99%)
What are the three forms of calcium that circulate in the blood
- free ionized form (active)
- bound to protein
- complex aniions
What is the normal total serum calcium
8.5-10.5 mg/dL
What is the net effect of parathyroid hormone
- increase serum calcium
- decrease serum phosphate
What is the active form of vitamin D
calcitriol
Net effect of calcitriol
- increase serum calcium
- increase serum phosphate
What does calcitriol do in the intestine
enhances intestinal cells to absord calcium and phosphate into the serum
Body response to low serum Ca in the bone? kindey?
bone: PTH stimulated osteoclastic activity which leads to increased serum CA
kidney: PTH promotes Ca resorption and stimultes hydroxylation of 25-hydroxyvitamin D via an enzyme
Body’s response to high serum Ca
parathyroid decreases PTH production
PTH response to increased serum calcium
PTH levels decrease
PTH response to decreased serum calcium
PTH levels increase
What does PTH do in the bone
- activates osteoclastic activity to increase serum calcium
- inhibits osteoblastic activity
What does active vitamin D do in the bone
promotes osteoblactic activity
What does calcitonin do in the bone
activates osteoblastic activity to decrease serum calcuim
What does the kidney do to maintain calcium homeostatsis
- reabsorbs calcium
- secretes phosphate in the urine
- increases serum alpha hydroxylase in order to convert calcidiol into calcitriol
Most common cause of hypocalcemia in adults
renal failure
Most common cause of hypocalcemia in children
nutritional deficiencies
Average age of hypoparathyroidism diagnosis
5th decade
Why is hypocalcemia from hypoparathyroidism rare
it requires all 4 parathyroid glands to be affected
Etiology of hypoparathyroidism
PARATHYROIDECTOMY THYROIDECTOMY -extensive raditation to neck -autoimmune -congenital
Symptoms of hypocalcemia
- emotional lability
- paresthesia
- shortness of breath
- voice changes
- vision changes
- personality changes
Physical exam findings with hypocalcemia
- seizures
- arrhythmia
- stridor
- tetant
- psychosis
What is Trousseau sign
flexion of the wrist and fingers
What is chvotek sign
abnormal reaction of the cranial nerves to stimulation on the face
What diagnostics are done for hypocalcemia? what do they show?
- EKG: qtc prolongation
- Total calcium (corrected calcium for low albumin): low
- PTH: low
Measuring calcidiol levels looks for what
liver dysfunction
What levels do you measure for kidney dysfunction
active vitamin D (calcitriol)
Treatment for hypocalcemia
- oral calcium (calcium carbonate)
- IV calcium (calcium gluconate)
What is the most common electrolyte abnormality in adults with malignancies
hypercalcemia
What is the most common cause of hypercalcemia
hyperparathroidism
What oncogene is linked to hyperparathyroidism
MEN 1, 2A and 2B
Etiologies for hypercalcemia
S.H.A.M.P.O.O sarcoidosis hyperparathyroid alkali milk syndrome metastasis pagets disease osteogenesis imperfecta osteoperosis
D.I.R.T d vitamin intoxication immobility renal tubular acidosis thiazides
Eitology of primary hyperparathyroid
- parathyroid adenoma
- hyperplasia
- carcinoma
- familial hypocalciuric hypercalcemia
Etiology of secondary hyperparathyroid
- chronic renal failure
- vitamin D deficinecy
Signs and symptoms of hypercalcemia
“bones, stones,groans, moans, psychiatric undertones”
Exam findings for hypercalcemia. skin cardiac GI renal MSK Neuro
exam is usually non contributory
skin: prutitus, skin tenting
cardiac: hypertension, LVH
GI: anorexia, N/V, constipation, abd pain
Renal: renal colic
MSK: bone fracture
Neuro: paresthesias, muscle weakness, depression
Diagnostic tests for hypercalcemia/hyperparathyroid
- calcium level
- PTH
- 24hr urinary calcium excretion
- chloride, phosphate
- PTHrP (malignancy)
- Bun/creatinine
- calcitriol/calcidiol
- EKG (narrow qtc)
Calcium, PTH and phosphate levels in primary hyperparathyroid
calcium- high
PTH- high
phosphate- low
Calcium, PTH and phosphate levels in secondary hyperparathyroidism
calcium- low to normal
PTH- high
phosphate- high to normal
Calcium, PTH and phosphate levels in secondary hyperparathyroidism
calcium- high
PTH- super high
phosphate- high
PTH release is increased by
- hypocalcemia
- hyperphosphatemia
- catecholamines
PTH is release is suppressed by
- hypercalcemia
- vitamin D
- severe hypomagnesemia
Scans done for hyperparathyroidism
- sestamibi scan
- US of the neck
Treatment options for hyperparathyoidism
- surveillance
- surgical
- pharmacological
- supportive
Medical treatment for hyperparathyroid
ASYMPTOMATIC PTS
- hydrate, avoid immobilization
- modest dietary calcium
- bisphosphonates
- d/c thiazides, vitamin A, calcium containing antacids
What is required for asymptomatic patients with hyperparathyroidism
annual serum calcium and creatinine
bone density scans every 1-2 years
What makes someone a surgical candidate for hyperparathyroidism
- symptomatic
- under the age of 50
- pregnant
- CrCl <60
- 24 hr urine calcium >400
- presence of nephrocalcinosis
- osteoperosis
Medications for treatment of hypercalcemia
- normal saline (dilution)
- loop diuretics w/ increased hydration
- bisphosphonates (inh osteoclastic)
- calcitonin (inh osteoclasts, promotes osteoblasts)
- gallium nitrate (direct inh of bone resorption)
Bisphosphonates used for hypercalcemia
- pamidronate
- zoledronic acid
Most common symptoms of hyperparathyroid
- nephrolithiasis
- fatigue
- bone disease
Genetic predisposition for parathyroid cancer
MEN1 and 2A
When is parathyroid cancer suspected
if symptoms are severe
- Ca levels >14
- PTH 5x normal
- palpable parathyroid
Treatment of parathyroid cancer
bilateral neck exploration with excision of tumor and ipsilateral thyroid lobe
How to treat parathyroid cancer with nodal involvement
radical neck dissection
When to check Ca levels after parathyroid cancer surgery
- 2 weeks post op
- 6 months
- anually
What is pagets disease
localized disorder of bone remodeling with excessive bone resorption followed by disorganized bone formation
What are the three phases of paget disease
- lytic
- mixed
- sclerotic phase
What happens during the lytic phase of paget disease
osteoclasts are more numerous and larger than normal
HIGH bone turnover
What happens during the mixed phase of paget disease
rapid increase in bone formation from numerous osteoblasts
What happens during the sclerotic phase of paget disease
bone if formed in a disorganized, woven pattern and is therefor weaker than normal
hypervascular bone state
Most common symptoms of paget disease
PAIN
- pathologic fracture
- osteoarthritis
- nerve impingement
- hearing loss
How is paget disease often diagnosed
accidentally by radiography or elevated alk phos
Treatment for paget disease
- surveillance for asymptomatic pts
- bisphosphonates
- calcitonin (intolerant to bisphosphonates)
- calcium
- vitamin D
Which bisphosphonates are used for paget disease
- zolendronic acid
- pamidronate
- risendronate
- alendronate
Preferred bisphosphonate for extensive disease or the elderly
IV zolendronic acid
Preferred disphosphonate for less extensive disease/young patients
risendronate or alendronate
