Hypercalcemia and Hypocalcemia Flashcards
(37 cards)
what are the 3 organ systems involved with Ca homeostasis?
skeleton, the kidneys and the intestines.
How does PTH act on the skeleton?
PTH directly stimulates osteoclastic
bone resorption, which releases ionized calcium and phosphate from the skeleton into the extracellular fluid.
How does PTH act on the kidneys
PTH directly inhibits renal calcium excretion but promotes renal phosphate excretion
how does PTH act on the intestines?
PTH stimulates conversion of 25 OH Vitamin D into 1,25 (OH)2 Vitamin by renal 1 alpha hydroxylase and thereby indirectly stimulates intestinal calcium and phosphorus absorption.
How does 1,25 (OH)2 Vitamin D raise serum calcium levels? by
Directly enhancing intestinal calcium and phosphorus
absorption and by promoting osteoclastic bone resorption, an effect that occurs mainly at high 1,25 (OH)2 Vitamin D levels.
What is the the storage form of vitamin D and thus inactive? is mostly inactive but is the major storage form of Vitamin D
25 OH Vitamin D
What is the active form of vitamin D that promotes intestinal calcium and phosphorus absorption.
1,25 (OH)2 Vitamin D
Where is Calcitonin produced?
produced by the parafollicular c-cells in the thyroid gland.
The calcium sensor receptor (CaSR) is a 7 transmembrane G-protein coupled receptor that senses the extracellular calcium concentration and signals the intracellular compartment to respond appropriately. CaSRs are present on the surface of ____
parathyroid cells, parafollicular c-cells and renal tubular cells
what does calcitonin do?
It lowers serum calcium by inhibiting osteoclastic bone resorption.
PTH is elevated or high normal in _______ and the rare congenital disorder ______ . PTH levels are low in all other causes of hypercalcemia.
Primary Hyperparathyroidism,
Familial Hypocalciuric Hypercalcemia
What are the causes of Primary Hyperparathyroidism (HPTH)?
Parathyroid adenoma ~85%
Parathyroid hyperplasia ~15% of cases;
Parathyroid Carcinoma < 1%
Primary hyperparathyroidism is ____ in 90% of cases, and _____ in 10%
sporadic,
familial
Almost all familial cases of HPTH
(familial HPTH, Multiple Endocrine Neoplasia 1, Multiple Endocrine Neoplasia 2A) result from _____
hyperplasia rather than an adenoma.
What is the presentation Primary HPTH
osteoporosis/osteopenia, kidney stones, gastrointestinal pain and psychiatric disturbances;
“bones, stones, groans and moans”
What is the treatment for Parathyroid hyperplasia?
Removal of 3 ½ parathyroid gland, with the remaining ½ gland being left in situ or auto-transplanted into a neck strap muscle or a forearm muscle
Name 5 conditions of Hyperparathyroidism where Surgery is Recommended
- Serum Calcium > 1 mg/dl above normal range
- Creatinine Clearance < 60 ml/min
- BMD T-Score < -2.5 or History of Fragility Fractures
- History of Kidney Stones
- Age < 50 Years
what is the choice for treatment of primary Hyperparathyroidism when surgery is contraindicated
Suppression of PTH secretion by calcimimetic drugs that bind to the CaSR (cinacalcet)
What is Secondary HPTH ?
Condition in which excessive PTH secretion occurs as a compensatory response to another primary disorder of calcium, vitamin D or phosphorus
What is the key to the diagnosis of secondary HPTH?
Elevated serum PTH level in association with
low or low normal serum calcium, low 25 OH Vitamin D, an elevated or high normal serum phosphorus, or
significantly reduced estimated glomerular filtration rate (eGFR)
Secondary Hyperparathyroidism: 4 Most Common Causes:
- Calcium Deficiency
- Vitamin D Deficiency
- Idiopathic Hypercalciuria
- Chronic Kidney Disease (Stages 4 and 5)
Define Hypercalcemia of malignancy
Occurs when solitary, metastatic or hematologic malignancies secrete hormones, cytokines or other mediators that promote aggressive local or diffuse osteoclastic bone resorption, flooding the circulation with calcium and thereby causing hypercalcemia.
The most common causes of hypercalcemia of
malignancy are ____
Carcinomas of the lung (especially squamous cell), breast, head and neck, kidney, bladder,
pancreas and ovary, multiple myeloma and lymphomas.
what is the most commonly identified mediator in Hypercalcemia of Malignancy?
PTH Related Peptide (PTH-RP)
