parathyroid Flashcards
role of PTH
- maintain serum Ca levels
where does PTH act
- bone
- kidneys
- intestines
PTH action on bone
- stimulate osteoclasts -> Ca resorption
PTH action on kidneys
- enhance Ca reabsorption
- synthesize active vit d
PTH action on intestines
- active vit D increases GI absorption of Ca
where is the majority of Ca found?
- 99% in bones
serum Ca
- only 1% of all Ca
- half is active
- half is bound to albumin
how do you calculate corrected Ca
- Ca measured + [0.8 (4 - measured albumin)]
calcitonin
- produced by thyroid gland
- opposes PTH
- “tones down” serum Ca
hungry bone syndrome
- parathyroid removal -> Ca influx into bones
- causes hypocalcemia
tx for hungry bone syndrome
- PO Ca
- IV Ca if severe- chvostek’s or trousseaus sign, seizures, arrhythmias
hypoparathyroidism
- rare
- need all 4 parathyroid glands to be affected
- d/t thyroid/parathyroidectomy, radiation, autoimmune, genetic
what is the most common cause of hypocalcemia in adults
- renal failure
- kidneys dont activate vit D
what is the most common cause of hypocalcemia in kids
- nutritional deficiencies
si/sx of hypoCa
- convulsions
- arrhythmias- QT prolongation
- tetany
- stridor
- spasms
- paresthesias
PE findings for hypoCa
- chvostek’s sign
- trousseau’s sign
- hyperreflexia
treatment for hypoCa and hypoparathyroidism
- PO calcium
- IV calcium if severe
- Vit D if hypopara, hungry bone syndrome, vit d def
- 1,000- 1,200 mg Ca daily
- Mg PRN
hypercalcemia
- common metabolic emergency
- assoc with up to 40% of cancer pts
what is the most common cause of hyperCa
- hyperparathyroidism
primary hyperparathyroidism
- single parathyroid adenoma
- hyperplasia
- carcinoma
- familial hypocalciuric hypercalcemia
secondary hyperparathyroidism
- CKD or vit D def -> increased PTH to try to increase Ca
tertiary hyperparathyroidism
- PT hyperplasia from prolonged secondary hyperPT -> increased PTH
- PTH elevated even after problem has been fixed
si/sx of hyperCa and hyperPT
- bones, stones, groans (abd), moans (psych)
hyperparathyroid imaging
- not used to make dx
- sestambi scan
- US
- CT
- MRI
- DXA scan
- Xray
xray findings for hyperparathyroidism
- osteitis fibrosa cystica
- salt and pepper skull
- brown tumor of long bones
surgical requirements for hyperparathyroidism
- age < 50
- serum Ca >1 above normal
- bone density < -2.5
- vertebral fx
- CrCl < 60
- 24 hour urine Ca > 400
- renal stone risk or evidence of stones
- symptoms
- pt preference
medical tx in asymptomatic hyperparathyroidism
- fluids
- modest dietary Ca
- Vit D based on age
- bisphosphonates
- d/c thiazides, vit A, Ca antacids
medical tx in symptomatic hyperparathyroidism
- fluids
- furosemide
- IV bisphosphonates
- calcitonin
- cinacalcet
- propranolol
ADRs of bisphosphonates
- AKI
- osteonecrosis of the jaw
- msk pain
- esophagitis
parathyroid ca
- least common endocrine malignancy
- MEN1 and MEN2A
- Ca levels > 14 and PTH normal
treatment for parathyroid ca
- surgical excision
- if nodal involvement - radical neck dissection
post op care for parathyroid ca
- check PTH and Ca at week 2, 6 mo, annually
- recurrence occurs 2-5 years post op
bones affected by paget disease
- skull
- thoracic and lumbar spines
- sacrum
- pelvis
- femur
- tibia
how is paget disease dx
- usu found incidentally
- imaging
- elevated alk phos
phases of paget disease
- lytic
- mixed lytic and blastic
- sclerotic
lytic phase of paget disease
- osteoclasts are more numerous and larger
- turnover is 20X higher
mixed lytic and blastic phase of paget disease
- rapid increase in bone formation but it is disorganized
sclerotic phase of paget disease
- disorganized bone formation dominates
- bone marrow infiltrated by CT nd BV
- bone is weaker than normal
si/sx of paget disease
- most asymptomatic
- pain most common sx if present
- bowed tibias
- kyphosis
- HA, hearing loss, increased hat size
complications of paget disease
- hearing loss
- pain, arthritis
- vertebral collapse/ fx
- CN palsies
- paralysis
treatment in asymptomatic paget disease
- surveillance
treatment in symptomatic pagets
- bisphosphonates
- calcitonin
- Ca and Vit D
- measure serum alk phos
