Ch.22Smith.ClinicalChemistry Flashcards
Fasting increases what form of bilirubin?
unconjugated bilirubin
Why are there variations in PCV with splenic contraction?
pain
excitement
catecholamine release
With blood loss usually see a decrase in both PCV/TP in what time frame?
24 to 48 hours
Extracellular fluid volume is determined by what electrolyte?
ECF: sodium
Intracellular fluid volume is determined by which electrolyte?
intracellular fluid potassium
Definition of hypertonic dehydration
water loss > loss of Na and K
What are examples of hypertonic dehydration?
hyeprnatremia
free water loss
feed/water deprivation
Define isotonic dehydraiton
water loss = loss of Na and K
Isotonic dehydration is caused by:
heavily sweating endurance horses
acute/ealry dairrhea
Define hypotonic dehydration
water loss less than loss of Na and K
Hypotonic dehydration causes
chronic diarrhea with access to fresh water
Intracellular fluid volume is what percentage of body weight?
40%
Extracellular fluid volume is what percentage of body weight?
20% BW
Sodium depletion occurs in what disease processes
vomiting
diarrhea
excessive sweating
adrenal insufficiency
What diseases of that lead to third spacing can cause hyponatremia?
peritonitis
ascites
bladder rupture
colon/viscus torsion
At what level are progressive neurologic signs seen with hyponatremia?
sodium <115 mEq/L
At what level does hyponatremia is severe/ can cause death?
sodium <100 mEq/L
What can cause falsely decreased sodium values?
marked hyperlipidemia or
hyperproteinemia
Common causes of hyponatremia
Relative water excess:
- Loss of sodium containing fluid (dec effective circulating vol)
- diarrhea
- excessive sweating
- blood loss
- fluid drainage: high-volume gastric reflux, high-volume pleural drainage
adrenal insufficiency
sequestration of fluid (third-space problems)
- peritonitis
- ascites
- pleuritis
- ruptured bladder
- torsion or volvulus of hte gut
False hponatremia: hyperlipidemia, hyperproteinemia, hyperglycemia
Uncommon causes of hyponatremia:
Water retention with normal effective circulating volume:
- psychogenic polydipsia
- renal disease
- inappropriate antidiuretic hormoen secretion
- use of diuretics
Common causes of hypernatremia
- pure water losses: panting, water deprivation
- sodium excess (wate restriction): salt poisoning, feeding only electrolytes, no free water
Uncommon causes of hypernatremia
water loss exceeds electorlyte oss:
- vomiting
- diarrhea
- burns
- intrinsic renal disease
- diuretics
- disbetes insipius: central neprhogenic
- hypertonic saline or sodium bicarbonate administraiotn
- mineralocorticoid excess
What percentage of potassium is in muscle cells and bone?
60-75% total body potassium
Where do herbivores receive potassium?
Herbivores have net intake of K that is regulated by kidneys
In Hypokaelmia, increased resting membrane potential leads to what clinical signs?
muscle weakness
impaire durien concentrating ability
arrhythmias
What are causes of depletion of total body potassium stores:
- Decreased intake and/or latered absorption
- INC GIT losses
- vagal indigestion, torsion of abomasum, ileus, diarrhea
- INC renal losses
- RTA (horses), diuretics, excess mineralocorticoid
- Early postpartum dairy cow
- anorexia and INC K losses
What will cause redistribution of potassium from ECF to ICF?
acute alkalosis
insulin or glucose amdinsitration
aggressive, rapid sodium bicarb administration–> alkalosis & profound hypoK
What is a cause of pseudohypokalemia?
severe lipemia
Causes of false hyperkalemia
- in vitro hemolysis
- prolonged storage of blodo (over 6 hours) w/o separation of serum or plasma
Common causes of hyperkalemia
- altered external balance
- hypovolemia w/ renal shutdown
- alterered internal balance
- metabolic acidosis
- virgorous exercise
- Uroperitoneum
Trimethoprim can cause hpyerkalemia through what mechanism?
Inhibits normal sodium reabsorption in cortical collecting duct
Alters transmembrane voltage–> impairs K secretion
Uncommon causes of hyperkalemia due to altered internal balance
- Hyperkalemic periodic paralysis in Quarter horses
- Diabetes mellitus
- tissue necrosis
- Renal disease
- Addison disease
Hyeprchloremic metabolic acidosis can occur in what disease in horses?
renal tubular acidosis
Disproportionate increases in chloride (in relation to sodium)
normal to low AG hyperchloremic met acidosis
compensation of primary resp alkalosis
Disproportionate decrease in chloride (in relation to sodium)
metabolic alkalosis
compensation for chronic primary respiratory acidosis
Hypochloremic metbaolic alkalosis,
loss or sequestration of chloride rich fluids occurs in what diseases?
displasced abomasum
reflux
diarrhea (Cl- absorbed in ileum, colon in horse)
heavy sweating in horses
diuertic use in horses
What is isotonic osmolality in healthy animals?
ECF ~300 mOsm
(280-310 mOsm in healthy animals)
Where does calcium live within the body and percentages?
99% total body Ca: teeth/bones
- 9% in cell membranes and endoplasmic reticulum
- 1% in serum
Serum calcium roles/function
- maintenance of neuromuscular exictability
- permeability of cell membranes
- conduction of nerve impulses
- muscle contraction
- clotting
Metabolism of calcium is regulated by:
- diet
- vitamin D + metabolites
- PTH
- Calcitonin
Serum Calcium adjusted by:
- intestinal absorption
- renal excretion (INC in horses)
- mobilization from bone
Ionized calcium fluctuates in what acid/base abnormalities?
DEC in alkalosis
**less H bound to albumin = more Ca bound
INC in acidosis
**excess H compete with Ca fo rnegative sites on albumin
At what level of hypocalcemia do dairy cows become recumbent?
<6 mg/dL
Systemic diaphragmatic flutter occurs d/t
phrenic nerves that fire synchronously with atrial depolarization
In renal injury what causes decrease in calcium?
acute renal tubular damage
**hroses, cattle, sheep
Hypocalcemia causes
H: hypoparathyroidism
A: Hypoalbuminemia
R: renal failure (not horses)
P: pancreatitis
I: intestinal malabsorption
S: spurious
A: alkalosis
L: lactation
E: ethylene glycol
Common causes of hypercalcemia:
D: Vitamin D toxicosis
R: renal disease
A: Addison’s
G: granulomatous
O: osteolysis
N: Neoplasia
S: spurious
H: primary hyperparathyroidism
I: Idiopathic
T: hypothermia
Phosphorus makeup within the body:
85%: structural basis of bones/teeth
15%: energy (ATP, ADP, MAP), membrane phospholipids, DNA, intracellular acid base buffering
Causes of hypophophatemia
primary hyperparathyroidism
hypovitaminosis D
alkalosis
starvation– refeeding syndrome
When phosphorus drops below <1.5 mg/dL , see clinical signs of:
hemolytic anemia
ileus
weakness
ataxia
seizure
Hyperphosphatemia can cause:
bone resorption:
- high phospohrus chelates Ca
- lowers ionized Ca
- activates PTH secretion
- increases bone resorption
- demineralizes bone
- fibrous osteoydstrophy results
When can hyperphosphatemia cause soft tissue mineralization:
when Ca x Phos >70
Cuases of hyperphosphatemia:
acute renal failure
nutritionals econdary hyperparahtyroidism (excessphosphate intake)
endurance exercise in horses
Higher noraml range in neonates
Low level of magnesium value:
<1.8 mg/dL
What is considered severe hypomagnesemia?
<1.0 mg/dL
Common causes of hypomagnesemia:
- Grass tetany
- winter tetany
- grass staggers
- calves on a milk only, magnesium defieint diet
- endurance exercise
- fatty liver syndrome
Temperature impacts what values on blood gas?
PO2
PCO2
Common causes of metabolic acidosis:
- rumen overload (lactic acidosis)
- ketosis
- pregnancy toxemia
- hypovolemic shock
- acute diarrhea
- colic when strangulated bowel
- strangulating abomasal torsion
- peritonitis
- uroperitoneum (ruptured bladder)
- execise above anaerobic threshold (normal response in horses)
Metabolic alkalosis compensation
hypoventilation (INC pCO2)
What causes paradoxical acid urine with hypochlormeic metbaolic alkalosis?
With Upper GI disease
Normal: Dehydration & RAAS activation–>
Na & Cl resorption & K excretion–> alkaline urine
Abnormal: Sodium & bicarb resorption & Hydrogen excretion–>
paradoxical acid urine
Common causes of metbaolic alkalosis
- sequestration of fludi n abomasum and ofrestomach in ruminants (internal vomiting fo rabomasal relfux)
- gastric reflux in hroses with ileus
- massive sweat loss in horses (endurance)
- salivary loss of chlorid ein horses with esopahgostomy
- use of diuretics (esp furosemide)
- functional pyloric stenosis
Compensation for respiratory acidosis
renal bicarb retention
** takes days.. only in chonri crespriaotyr acidosis
Common causes of respiratory acidosis:
Primary pulmonary disease
- obstruction of upper airway, laryngeal dema, aspiraotn pneumonia, pneumothorax, chornic obstructive pulmonary dz
Depression of respiratory center in CNS
- gneral anesthsia w/ inappropriately assited ventilation
- drugs: opiates, anesthetics, tranquilizers
- CNS dz
What is included in anion gap calculation?
anion gap=
(Na + K) - (Cl + HCO3)
normal anion gap
12 - 16 mmol/L
Causes of decreased anion gap:
- hypoproteinemia
- hyperchloremic metabolic acidosis (usu hypokalemic)
- overhydration
Causes of increased anion gap:
- lactic acidosis (D and L)
- ketoacidosis
- uremic acidosis
- ethylene glycol
- assoc with dehydration & contraction alkalosis
what percent of bicarb accounts for the CO2 in blood?
95% of CO2
bicarb calculation (adult)
base deficit mEq x BW (kg) X 0.3
blood gas normal bicarb?
24 mEq/L
Increase SDH
hepatocellular damage & leakage of enzymes
**liver insult secondary to absorption of bacteria from poral circulation
creatine kinase (CK) is found where in body?
cardiac & skeletal muscles
**most commonly assoc with rhabdomyolysis
What is the half life of creatine kinase in horses and cattle?
horses: 2 hours
cattle: 4 hours
When does activity of creatine kinase (CK) peak at?
6 to 12 hours
**can normalized within 2 4hours
a persistant increase in creatine kinase indicates:
pactive and continuing mm damage
what value of creatine kinase give a guarded prognosis in downer cows?
downer cows >3,500 IU/L
aspartate aminotransferase (AST) is found in:
skeletal mm
cardiac mm
rbc
liver
kidneys
What is the half life of AST?
>2 days in LA spp
How long can AST remain elevated in following myonecrosis or liver damage?
up to 10 days
Gamma-glutamyltransferase (GGT) is membrane bound specifically to what location:
Biliary tract
GGT can be found in what other tissues?
Pancreas, GIT, kidney, mammary gland & repro tract **do not see serum GGT increase
In thoroughbred race horses what liver enzyme is elevated, but responds to rest/decreased work?
GGT **unknown pathophysiology
Alkaline phophatase is a marker of:
Biliary disease
What are enzymes that are markers of hepatocellular damage?
ALT AST SDH
What are markers of cholestatic disease?
ALP GGT Tbili Cholesterol
What are indirect markers of hepatocellular function?
Albumin Glucose BUN Cholesterol
What are direct tests of hepatocellular function?
Bile acids Provocative bile acids test Ammonia Ammonia tolerance test
Common causes of elevated SDH
Severe anoxia Acute liver disease Liver abscess Secondary to damaged bowel (strangulating intestinal lesion, acute toxic enteritis) Chronic liver failure
LDH is released from what organs?
Heart Liver Kidney Muscle
Bilirubin is a break down product of:
Heme (component of hemoglobin)
Direct bilirubin is
Conjugated bilirubin
Indirect bilirubin is
Unconjugated (pre-hepatic), albuminboun
Causes of increased indirect bilirubin:
Anorexia (in horses) Increased production LIver disease/failure Hepatic uptake decreased Conjugation decrease Hemolytic anemia
Increase in conjugated bilirubin causes
Intrahepatic cholestasis (cholagniohepatitis) Extrahepatic bile duct obstruction Cholelithiasis Neonatal isoerythrolysis
Hypoglycemia common causes
Inappetance in newborns Sepsis Pregnancy toxemia Endotoxic shock (late stages) Hepatic failure
Hyperglycemia common causes:
Acute severe colic in horses Stress and excitement Cushing syndrome Glucocorticoid administration Xylazine administration
Why is creatinine more reliable than urea nitrogen (BUN) in ruminants?
Because urea can be secreted in saliva and metabolized by rumen microbes
Common causes of pre-renal azotemia
Reduce renal perfusion Hypovolemia Congestive heart failure Dehydration alter endurance exercise
Common causes of renal azotemia
Acute renal failure Chronic renal failure
Common causes of post renal azotemia
Urolithiasis Renal calculi Ureteral calculi Urethral calculi Ruptured bladder
Where is urea produced?
In liver from ammonia (derived from AA catabolism)
Urea is excreted by what organs?
Kidneys (glomerular filtration) Intestine Saliva Sweat
Why in liver failure do we see decreased BUN?
Due decreased production
Causes of decreased BUN
Liver failure Neonatal animals (BUN normally lower in adult)
Hyposthenuria
1010
Hypersthenuric
>1030 -1035
Isosthenuric
1008-1012
Causes of hypothenuria:
Altered release of or response to ADH DI and nephrogenic DI Psychogenic polydipsia Medullary washout Chronic liver failure
Causes of USG <1020 in the face of dehydration?
Primary renal disease Diabetes insipidus Nephrogenic diabetes insipidus Medullary washout
Ruminant renal threshold for glucose
100-140 mg/dL
Equine renal threshold for glucose
160-180 mg/dL
Glucosuria without hyperglycemia indicates
Renal tubular damage
Casts in urine are
Accumulations of proteins and cellular materials in renal tubules
Hyaline casts in urine are caused by:
Glomerulonephritis Fever with passive congestion Severe dehydration
What ketones are detected in urine?
Acetone & acetoacetate **Do not detect beta-hydroxybutyrate
