Flashcards in Calcium metabolism Deck (31):
What is the explanation for hypercalcemia 90% of the time?
1. Primary hyperparathyroidism
2. malignancy-secreting PTHrP
What is the most common form of primary hyperparathyroidism, producing hypercalcemia?
What is the second most common form of primary hyperparathyroidism?
Which types of malignancies can cause secretion of PTHrP and hypercalcemia?
small cell cancer (esp of lung)
renal cell carcinoma
breast mets to lung
10% of the time, what is the reason for hypercalcemia?
lots of Vit D ingested
lots of Ca++ ingested
Granulomas: macrophages activate Vit D. THink TB, sarcoidosis
Increased bone turnover
Which types of things can cause increased bone turnover--leading to hypercalcemia?
Vit A intoxication
Which diuretics increase calcium in blood, which decrease it?
Loops lose calcium. Thiazides retain it.
What are the signs/symptoms of hypercalcemia/hyperparathyroidism?
Stones, Bones, Groans, Psychiatric Overtones
What types of stones are produced by hypercalcemia?
Kidney stones (ca++)
What types of bone issues do you see with hypercalcemia?
osteitis fibrosa cystica
What are the features of osteitis fibrosa cystica?
subperiosteal bone respiration of the radial aspect of the middle phalanges
tapering of the distal clavicle
salt and pepper skull
brown tumors of the long bones
What are the abdominal groans of hypercalcemia?
peptic ulcers (increase in Ca++ causes an increase in gastrin)
What are the psychiatric overtones of hypercalcemia?
confusion, stupor, coma
What are other random features of hypercalcemia?
proximal muscle weakness
Which cells make parathyroid hormones?
chief/principal cells of parathyroid gland
What do the oxyphil cells of the parathyroid gland do?
no one knows!
they are packed with mitochondria, show up at puberty, and increase w/ age.
How does PTH stimulate bone turnover?
stimulates osteoblasts. They release RANKL that stimulates osteoclasts
Which carcinoma causes increased calcitonin?
medullary thyroid carcinoma
**not reactive to radioactive iodine treatments
C cells of thyroid aka parafollicular cells secrete calcitonin
What is the nerve supply to the parathyroid gland?
cervical sympathetic ganglion
controls blood flow, but not stimulation
What are the general causes of hypocalcemia?
Vit D deficiency
What are some common causes of hypoparathyroidism?
pseudohypoparathyroidism (kidney doesn't respond to PTH)
Di George Syndrome
Why does acute pancreatitis lead to hypocalcemia?
don't get those fats dealt w/ w/o pancreatic secretions. Ca++ in gut combines w/ fatty acids-->soaps
Chovstek and Trouseau signs are seen w/ hypo or hypercalcemia?
What is a type of pseudohypoparathyroidism?
Type 1a: Albright Hereditary Osteodystrophy
What are the special features of Albright Hereditary Osteodystrophy?
short stature and obesity
underdeveloped 3rd and 4th phalanges
osteitis fibrosa cystica
Where are Ca++ and PO4 reabsorbed in the kidney?
Describe the relationship b/w magnesium and PTH secretion?
Low Mg++ -->PTH secretion
Super Low Mg-->Decreased PTH secretion
What are some causes of low magnesium?
Maggie and her DADA
High PTH, High Ca++, Low phosphate...cause of hyperparathyroidism?
most likely parathyroid adenoma
high PTH, Low Ca++, High phosphate...cause of hyperparathyroidism?
chronic renal failure, can't reabsorb anymore!
*can also be caused by Vit D deficiency-may get rickets