Cross Species - Chemistry Electrolytes Flashcards
what electrolytes are included on a biochemistry panel?
sodium, potassium, & chloride
what minerals are included on a biochemistry panel?
calcium, phosphorus, & magnesium
what is the predominant extracellular cation on a biochemistry panel? what is it tightly linked to?
sodium - extracellular fluid (hydration status!!)
what are the top causes of hypernatremia?
water loss in excess of sodium, so dogs/cats - gi fluid loss, adipsia - CNS disease & water deprivation, & excessive sodium ingestion seen in salt poisoning in calves
what are the top causes of hyponatremia?
hypotonic fluid loss - DKA, gi loss (severe diarrhea in horses & cattle, but especially horses), addison’s disease, & diuretic administration + volume overload/excessive water intake
why can’t you correct hyponatremia too quickly? what is the maximum rate?
CNS signs can occur with rapid correction - max rate, no greater than 0.5 mEq/L/h
what is the major intracellular cation? why is it tightly controlled?
potassium - very important for cellular function!!! plasma level is very low compared to sodium
what are the top causes of hyperkalemia?
spurious (thrombocytosis, hemolysis, EDTA coagulant), uroabdomen (foals, obstructive uropathy in dogs/cats), oliguric/anuric acute renal failure, addison’s disease, HYPP in horses, neonatal bovine diarrhea, & metabolic acidosis
what are the top causes of hypokalemia?
decreased intake, increased excretion/loss, & transcellular shifts
what are some examples of increased excretion/loss that lead to hypokalemia?
increased excretion/loss - feline CKD, loop diuretics, gi loss, & sweating in horses
what are some examples of transcellular shifts that lead to hypokalemia?
alkalemia, insulin or dextrose administration, & hypokalemia in cattle 3 months post partum
what is the ratio of chloride to sodium?
1:1 but it will be slightly lower than sodium in plasma
why should you always interpret chloride in conjunction with sodium?
they move together!!!!
what does it mean if the change in both sodium & chloride is roughly the same? what if it is different?
if the same - free water loss or gain, if different - acid-base disturbance or loss of Cl in excess of sodium
what are the top causes of hyperchloremia?
drug administration (potassium bromide) & hyperchloremic metabolic acidosis (secondary to renal disease)
what are the top causes of hypochloremia?
hypochloremic metabolic alkalosis, loss of Cl rich fluid
what are some causes of loss of chloride resulting in hypochloremia in dogs/cats? cattle? horses?
dogs/cats - gastric acid with high causes of vomiting so gastric outflow tract or proximal duodenal obstruction, cattle - abomasal outflow tract obstruction & renal disease, & horses - ptyalism, gastric reflux, & diarrhea
what drug can result in hypochloremia?
loop diuretics
what are the 3 forms of calcium?
50/55% free/ionized (not measured by chemistry), 35/45% protein bound mostly to albumin which is measured, & 5/10% complexed with anions that is not measured
if calcium is abnormal on a chemistry panel, what should you measure?
ionized calcium
in dogs, how can calcium be adjusted?
measured calcium - albumin + 3.5
T/F: changes in blood albumin affect total calcium but not ionized
true
what is a normally adjusted calcium?
change in the measured calcium likely due to change in albumin
T/F: changes in ionized calcium are physiologically significant
true
what should calcium be evaluated with?
phosphorus to evaluate calcium homeostasis
how is the serum calcium phosphate product measured? what is the risk if it is over 70?
total calcium * phosphorus - if greater than 70, high risk of tissue mineralization (especially renal) which is a negative prognostic indicator for canine renal disease
how do you rule out toxicosis as a cause of hypercalcemia?
measure vitamin D levels
what are the main causes of hypercalcemia in dogs?
paraneoplastic hypercalcemia of malignancy!!! also primary hyperparathyroidism & addison’s
what does a normal PTH with hypercalcemia indicate in dogs & cats? why?
inappropriate - indicates parathyroid related disease because PTH is controlled by negative feedback so it should be low with hypercalcemia
T/F: PTHrP can be increased with hypercalcemia of malignancy
true
what are the main causes of hypercalcemia in cats?
idiopathic, chronic renal disease, & paraneoplastic
what are the main causes of hypercalcemia in horses?
chronic renal disease & paraneoplastic
what are the main causes of hypercalcemia in cattle?
iatrogenic calcium administration
what is the most common cause of hypocalcemia? what do you measure to determine if it is significant?
low serum albumin - ionized calcium
what are the main causes of hypocalcemia in dogs?
severe illness, primary hypoparathyroidism, acute pancreatitis, PLE (can cause true hypocalcemia especially in yorkies with lymphangiectasia), & ecclampsia
what are the main causes of hypocalcemia in cats?
severe illness & renal disease
what are the main causes of hypocalcemia in cows?
milk fever
what are the main causes of hypocalcemia in horses?
colic in horses & hypocalcemia tetany
where does most phosphorus exist in the body?
most exists as oxidized phosphate in bone
how is phosphorus excreted?
urinary excretion in monogastrics & salivary excretion in adult ruminants
what risk do you run if phosphorus is very increased? what if you have significant hypophosphatemia?
increased - tissue mineralization, decreased - erythrocyte membrane instability & hemolysis
what are the top causes of hyperphosphatemia in small animals?
decreased renal excretion, pre-renal (dehydration, renal, or post-renal obstruction
what are the top causes of hyperphosphatemia in horses?
acute renal failure, nutritional secondary hyperparathyroidism, endurance exercise, & vitamin D toxicity
what are the top causes of hyperphosphatemia in cattle?
uncommon - usually due to dehydration
what is a cause of hyperphosphatemia in young dogs?
bone growth
what do you expect to see with calcium & phosphorus levels in an animal with primary hyperparathyroidism?
usually increased calcium & decreased phsophorus
what is a big cause of hypophosphatemia in dogs & cats?
insulin therapy for DKA
what are some causes of hypophospatemia in horses?
chronic renal disease, gi disease, & starvation
what are some causes of hypophosphatemia in cattle?
post-parturient hemoglobinuria in dairy cattle, severe illness, & urolithiasis
what is the major intracellular cation second to potassium? what is it a critical cofactor for?
magnesium - critical cofactor for ATP
how is magnesium measured?
total concentration measured by chemistry analyzers - some machines will do in house ionized magnesium
T/F: hypomagnesemia is typically more clinically relevant than hypermagnesemia
true
when should you measure levels of magnesium?
unexplained hypocalcemia, refractory hypokalemia (supplement magnesium to help correct), & sudden death in ruminants
T/F: hypermagnesemia is an uncommon lab abnormality to see on a chemistry panel
true
what are some iatrogenic causes of hypermagnesemia in horses?
MgSO4 administered as a gi cathartic, or iv supplementation, or either way as a calming agent
what is the top cause of hypomagnesemia in horses & small animals?
critical illness
T/F: horses can get hypomagnesemia from sweating in an endurance/competition or with exhaustion syndrome
true
T/F: in small animals, diuresis increases urinary loss of magnesium causing hypomagnesemia
true
what is the top cause of hypomagnesemia in ruminants?
grass tetany
