Hormones Flashcards
What are the 3 fractions in serum/plasma for Ca?
fCa: free calcium-hormones regulate this concentration
Ca/Pr: Protein Bound-Conc changes with protein conc
Ca/A: Bound to anions other than proteins-change with anion conc
Which type of Calcium should not filter through the glomerulus?
Protein bound
Where do animals get their Vit D from?
Hepatocytes make it or Diet
Horses don’t have which enzyme in the making of Vit D, so what do they rely on?
They dont have 1-hydroxylase
So they have to rely on Calcitriol
What regulates free Ca?
PTH and Vit D
altered by plasma pH
What happens when you have a low conc of Free Ca?
inc in PTH and Vit D
This mobilizes Ca from bone, inc absorption by intestines, and decreases the excretion by the kidneys
What tube do you use for analysis of Ca?
Purple or blue top
NOT EDTA or citrate will chelate
Whats happening if there is a change in total calcium?
Change in one or more fraction conc
What is Ca/Pr dependent on?
TP and Alb concentrations
What should the ratio be of the forms of Ca
Ca/A = 10%
Ca/Pr = 40%
fCa= 50%
There is never an equilibrium, so these are estimates
What are some causes of hypercalcemia?
Primary Hyperparathyroidism
Hypervitaminosis D
Dec Urinary Excretion
Humoral Hypercalcemia of malignancy (HHM)
Why would you have decrease in urinary excretion of Ca?
Renal Failure
Addisons-hypoadrenocortisim
Why is Equine Renal Failure Important
Dec GFR, dec clearance of Ca and Ca/A, which inc Free calcium. COMMON IN HORSES
bc of excess dietary Ca, switch from alfalfa to grass
Why does Adddisons create a hypercalcemia?
Hypovolemia-activation of RAAS-inc proximal tubular resoprtion of Na and Ca which increases free calc
What are some causes of hypocalcemia?
Hypoalbunimeia
primary hypoparathyroidism
hypovitaminosis D
Increase urinary excretion
Pregnancy/parturient/lactational
Why would hypoalbuminemia cause hypocalcemia?
remember Ca/Pr is controlled by proteins and albumin concentration and that any change in Total Ca could be due to any of the fractions
maybe inflammation?
What is Rickets dz?
Lack of Vit D, calc or phosphate. leads to softening and weakening of the bones
Would chronic renal dz lead to hypovitaminosis D? and why?
Yes-bc remember it causes secondary hyperparathyroidism which can cause and inc in PTH bc of dec Ca.
What happens if you have a sudden addition of PO4 to plasma?
Ca/PO4 complexes form and those complexes are engulfed by macrophages and thus lowers both Ca and PO conc in plasma. The tissues that are already damaged will calcify
Healthy tissue does not calcify bc of hypercalcemia
What tube do you use if you want to measure free ca?
Red top-Serum
What happens if you get air in your free calcium sample?
pH shifts down which will cause more Ca to bind which means less free calcium.
As H+ leaves the protein, it frees a negative charge for Ca to bind to
Disorders of total calcium are typically disorders of?
Free calcium
What are the exceptions to the general statement of dz or tcal are of fcal?
Decrease in total cal due to hypoalbuminemia—bc this would be Ca/Pr
Inc binding of Ca to anions
WHat are some reasons for hyperphosphatemia
Decreased urinary PO4 excretion-primary hypoparathryroidism
Inc absorption from intestine: phpsphate enema, hypervitaminosis D
Shifting from ICF to ECF-rhabdomyolysis
hemolysis
Age-GH increasing renal resorption
Causes of Hypophosphatemia?
Increased urinary excretion
Decreased P03 absorption from intestine-anorexia
Shift from ECF to ICF-hyperinsulinisn
Defective mobilization of PO4 from bone
What are the 3 fraction of Mg
fMg-55%
Bound Mg-proteins and anions
TMg
Does Mg play a role in PTH activity?
YES! essential!
Where is most Mg found at?
Bones and Tissues
What are some causes for hypermagnesemia?
Decreased urinary excretion-renal failure, dec GFR
Increased PTH
Pseudohypermagnesemia-in vitro hemolysis or delayed removal of RBCs from serum from clot
Causes of hypomagnesemia
Hypoproteinemia
Anorexia
Osm diuresis, ketonuria
Grass tetany in cattle-high in PO4, and K but poor Mg absorption by rumen
When does PTH become stimulated?
Decreased fCa and decreased vit D
What could cause an increas in PTH
Neoplasms
Hypercalcemic disorders
Hyperplastic parathyroid glands: CRD-secondary hyperparathyroidism
What could cuase a decrease in PTH
Damaged parathyroid gland
Inhibited parathyroid glands
PTH-rp is produced by? and promotes/
Produced by many cells
Promotes Ca balance in fetus
What are some causes of an increase serum PTH-rp
HHM
lymphoma, anal sac carcinoma, carcinomas
What are you classic changes in CRF
Dec GFR- Inc P and Ca/A
Dec Vit D: dec Ca–PTH—inc Ca and dec P
If a porous Glom: Proteinuria: Dec Ca and P
