Renal 3 Flashcards
3 main regulators of serum Ca2+ and phosphate concentrations are
PTH, vitamin D (note calcitriol is the active metabolite) and calcitonin
normal calcium homeostasis: what happens when blood calcium levels decrease?
PTH from parathyroid gland increases serum Ca2+ and decreases serum P by promoting:
- calcium resorption from bone matrix
- calcium absorption in proximal and distal tubules of kidney and increase renal excretion of phosphate too) from tubules of kidney
- indirectly: increases calcitriol from kidney, which indirectly increases intestinal Ca (and P) absorption
what does vitamin D do, in presence of PTH to increase serum Ca2+ and P
- Kidneys – promotes reabsorption of Ca2+
- Intestine – promotes absorption of Ca2+ & P 3. Bone – promotes release of Ca2+ & P
what is secreted in response to high calcium and has a net result of decreasing serum Ca2+
calcitonin
ow does calcitonin secretion result in decreased serum Ca2+
secreted in response to high serum Ca2+
bone: inhibits osteoclastic bone resorption of Ca2+
kidneys: inhibits Ca resorption
what are the 3 forms of calcium in circulation that make up TOTAL CALCIUM? which is biologically active and hormonally regulated
free or ionized calcium (iCa): 50%, this I the biologically active and hormonally regulated form
protein-bound calcium: 40-45%; 80% is bound to albumin and 20% to globulin
non-protein anion bound calcium: 5-10%
total serum calcium can be affected by hypoalbuminemia, i.e. can see
hypocalcemia (total Ca in serum) with this BUT iCa will remain WNLs
hypoalbuminemia
***total serum calcium includes a large portion of protein-bound calcium, so does not always reflect the true change in the biologically active ionized form. what should we measure instead to get a more accurate value for Ca in disease states?
iCa
only the free ionized form (iCa) is biologically active & hormonally regulated (by PTH, Vitamin D & calcitonin)
3 pathologic disorders iCa will increase in? and which one especially in horses?***
decreased renal excretion esp. in horses, increased GI absorption, osteolysis
3 pathologic disorders iCa will decrease in
decrease Gi absorption, increased renal excretion, increased loss in milk
alkalosis _______ serum iCa, while acidosis ______ serum iCa
decreases, increases
hypercalcemia: give HARD IONS (actually HHARRD IONSH)
hyperparathyroidism
humoral hypercalcemia of malignancy
Addison’s disease
renal disease
raisins
vitamin D toxicity
idiopathic (young to middle aged cats)
osteolytic bone lesions
neoplasia/humoral hypercalcemia of malignancy
spurious (retest to ensure consistency)
hypothermia
potential causes of hypercalcemia: humoral hypercalcemia of malignancy, HMN, is a neoplasm that secretes what, and is referred to as what
PTHrp parathyroid related protein
paraneoplastic hypercalcemia
potential causes of hypercalcemia: humoral hypercalcemia of malignancy: give 2 examples in dogs
lymphoma apocrinee gland adenocarcinoma of anal sac (ASA, ASAC); pulmonary, nasal, mammary, squamous cell, thyroid, thymic carcinomas
potential causes of hypercalcemia: humoral hypercalcemia of malignancy: give 2 examples in cats
pulmonary, undifferentiated and thyroid carcinomas, lymphoma
potential causes of hypercalemia: humoral hypercalcemia of malignancy: give 2 examples in horses
carcinoma, lymphoma
potential causes of hypercalcemia: ***hypoadrenocorticism will be about 30% of hypercalcemia cases and has a multifactorial pathogenesis and is typically mild.
what happens to levels of tCa, iCa, PTH, PTHrp, and vitamin D?
increased tCa, normal others
potential causes of hypercalcemia: primary hyperparathyroidism results from a PTH secreting adenoma or carcinoma. what are clinical signs? signalment?
PUPD, urinary incontinence
Gshep and keeshonds
potential causes of hypercalcemia: primary hyperparathyroidism results from a PTH secreting adenoma or carcinoma.
what happens to levels of tCa, iCa, PTH, PTHrp, and vitamin D?
increased iCa, decreased P, normal to increased PTH, normal PTHrp
tCa and vit D????
potential causes of hypercalcemia: can be due to increased vit D activity. name 3 EXOGENOUS sources of vitamin D
vit D containing rodenticides, human psoriasis medications, or some plants, eg. jessamine or Solanum
potential causes of hypercalcemia: can be due to increased vit D activity. name 1 ENDOGENOUS sources of vitamin D
granulomatous inflammation, because macrophages produce vitamin D (calcitriol)
potential causes of hypercalcemia: an uncommon cause is ________ eg. multiple myeloma
osteolytic lesions
potential causes of hypercalcemia: how does chronic renal failure lead to hypercalcemia in horses?
horses normally excrete excess ca2+ by kidneys, this decreased GFR causes hypercalcemia
potential causes of hypercalcemia: hypercalcemic renal failure occurs in horses most commonly. when could it occur in dogs?
how does chronic renal failure lead to hypercalcemia in horses? can hypercalcemic failure occur in other species, and when?
raisin or grape toxicosis
