C10 Laboratory Evaluation of Lipids & Proteins

Question 1

Micelles contain:

Answer 1

Long chain fatty acids
Triglycerides
Cholesterol
Vitamins AEDK

Question 2

Lipid digestion overview

Answer 2

• come in through digestive tract, where lipids are emulsified by bile salts into micelles
  > pancreatic lipase interacts with micelles and tears them apart into different types of fatty acids
  > these products pass into mucosal cells

Question 3

what causes lipemic samples?

Answer 3

• triglycerides contained into chylomicrons
• post-prandially, chylomicrons come into the body through the intestine and travel into various tissues
  > the triglycerides in them are stripped out and used for other purposes
  > most commonly a lipemic sample is caused by triglyceride-containing chylomicrons

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• nonpost-pranidal, we can can have hyperlipidemia involving VLDL, which also contain triglycerides

Question 4

Post-Prandial (Physiologic) Hyperlipidemia
- when does this occur? what does this mean for blood collection?

Answer 4

• when triglycerides in the chylomicrons are high
• increased chylomicrons starting 1-2h after a meal, peaks at 6 hours, tapers off at 16h
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• Lipemia > interferes with many commonly analyzed components of serum
• Fast 12 h before collecting blood
• If still lipemic – additional tests > some disease causing pathologic hyperlipidemia

Question 5

Lipemic Blood Sample = Interference!
- how does it interfere with light and mess up our samples?

Answer 5

• The line on the refractometer – false ↑ TP
• Biochemical analyzer > spectrophotometric techniques

Question 6

Lipemic Blood Sample = Interference!
- how does this interfere with cell membranes and mess up our samples?

Answer 6

• RBCs – enhances hemolysis

Question 7

Clinically Important Lipids in Blood

Answer 7

1. Triglycerides
   * Nonesterified fatty acids (NEFAs, aka free fatty acids, LCFA)
2. Cholesterol
3. Ketones (as fat-related compounds)

Question 8

Hypocholesterolemia:
- seen when, most commonly?

Answer 8

1. Liver failure / portosystemic shunt
   * Often results in hypocholesterolemia
   > not enough liver available to make cholesterol, or nothing is going to the liver so it can’t do anything
   * NB: Animals with concurrent cholestasis
   > no bile or cholesterol is leaving, backs up into blood
2. Hypoadrenocorticism (Addison’s disease)
   > unknown etiology, perhaps immune mediated

Question 9

Hypocholesterolemia and hypotriglyceridemia concurrently:
- seen when?

Answer 9

1. Maldigestion / malabsorption
   > maldigestion = no pancreatic lipase to break down micelles. Malabsorption = its just not getting in.
   > steatorrhea
2. Protein losing enteropathy
   > lymphoma, lymphangectasia…
3. Cachexia/starvation

Question 10

Hyperlipidemia - categories

Answer 10

1. Primary hyperlipidemia – inherited
   > schnauzers
2. Secondary hyperlipidemia – everything else
   > more common

Question 11

Secondary Hyperlipidemia – Pathologic Altered Clearance or Cellular Uptake
- what is this associated with in cats, dogs, and horses, usually? (very generally)

Answer 11

• some sort of endocrinopathy

Question 12

Secondary Hyperlipidemia – Pathologic Altered Clearance or Cellular Uptake

• specific causes in the dog

Answer 12

Dog
* Hyperadrenocorticism, hypothyroidism, diabetes mellitus (DM), cholestasis, pancreatitis, obesity
* Protein-losing nephropathy (PLN), glucocorticoids, phenobarbital
* Idiopathic hyperlipidemia of miniature schnauzers with pancreatitis < mechanism not determined

Question 13

Secondary Hyperlipidemia – Pathologic Altered Clearance or Cellular Uptake

• specific causes in the cat

Answer 13

• Negative energy balance (NEB), cholestasis, hyperthyroidism, DM
• Protein-losing nephropathy (PLN), obesity, glucocorticoids
• pancreatitis < mechanism not determined

Question 14

Secondary Hyperlipidemia – Pathologic Altered Clearance or Cellular Uptake

• specific causes in the ruminant, pony, miniature horses, donkeys, sheep, llamas

Answer 14

• Negative energy balance
• Pituitary Pars Intermedia Dysfunction & Equine Metabolic Syndrome – horses & ponies (obesity)
• Pregnancy toxemia of sheep

Question 15

Lipid Metabolism in Ruminants Assessment in the Transition Period
- what do we measure? what do we see?

Answer 15

↑NEFAs – pre-calving
* = negative energy balance / stress conditions
* Mobilization of fat from reserves
* ↑ risk:
> LDA, subclinical ketosis, RFM, 1- 1.5 kg/d ↓ milk production, early culling
* If prolonged – fatty liver

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Beta-hydroxybutyrate (β-OHB) – post-calving
* NEB
* Ketosis, fatty liver
* Pregnancy toxemia in sheep

Question 16

Protein Measurement (g/L)
- what and where?

Answer 16

1. Plasma protein =
   a. Albumin
   b. Globulins
   c. Fibrinogen – inflammation – LA
2. Serum total protein (TP)
   a. Albumin
   b. Total Protein - albumin = globulins

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3. Serum protein electrophoresis quantitates & separates
   * Albumin and the 5 fractions of globulins in serum

Question 17

Hyperfibrinogenemia causes

Answer 17

• Inflammation in LA
• Dehydration (hemoconcentration)

Question 18

Hypofibrinogenemia causes

Answer 18

• Consumptive coagulopathies – DIC
• Decreased production
  > Liver failure; liver is what produces fibrinogen

Question 19

Hyperproteinemia – The Patterns
- what might we see?

Answer 19

↑ albumin ± ↑ globulins
* Dehydration (hemoconcentration)
>Skin tent / PCV / urea / creatinine / USG…

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↑ globulins and ↓ albumin
* Increased protein synthesis
> Infectious & non-infectious inflammatory disease
> B-cell neoplasia (lymphoma / multiple myeloma)
> in this case alnbumin decreases to make sure plasma oncotic pressure is balanced

Question 20

how can we tell normal values in an electrophoresis measurement from a chronic inflammatory response from a monoclonal gammopathy

Answer 20

NORMAL:
-tons of albumin, everything else pretty low

CHRONIC INFLAMMATORY:
- lower albumin
- increased alpha-1 and -2 peaks (pro-inflammatory cytokines)
- decrease in beta region (negative acute phase reactant here)
- broad-based increase in gamma globulins due to stimulation of B cells and plasma cells

MONOCLONAL GAMMOPATHY
- spike in gamma region
> One clone of a single type of neoplastic plasma cell, making a single type of immunoglobulin
- As tall or taller & as narrow or narrower than the albumin spike

Question 21

Monoclonal Gammopathy – Multiple Myeloma
- required findings to diagnose?

Answer 21

Need 2 of the following 4:
1. Monoclonal gammopathy
2. Increased plasma cells in bone marrow
* >20%
* unusual to see plasma cells in peripheral blood
3. Bence-Jones proteinuria (light chains)
4. Lytic lesions in bones (rare in cats)

Question 22

Common Causes of Hypoproteinemia

Answer 22

1. Increased loss
2. Dilution
3. Inadequate production
4. Inadequate intake

Question 23

Hypoproteinemia – The Patterns of Loss
↓ albumin and ↓ globulins
- why?

Answer 23

↓ albumin and ↓ globulins
* Hemorrhage / blood suckers
* Protein Losing Enteropathy > gut becomes ‘holey’ and we lose very large globulins and smaller albumin out the back end (lymphangectasia, lymphoma… can cause)
* Malabsorption/maldigestion
* Cachectic states
> inadequate plane of nutrition
* Exudative skin disease (burns / large wounds - plasma oozes out, can’t be recaptured)

“Panhypoproteinemia”

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– Dilution
* Hemodilution (eg. LRS)
* Repeated effusion draining

Question 24

what does panhypoproteinemia look like on the electophorogram?

Answer 24

• decreased albumins
• decreased gamma globulins
• decreased beta and alpha-2 region

Question 25

when do we see hypoalbuminemia

Answer 25

↓ albumin * PLN > only place we will see decreased albumin but not globulins is through the kidney * Hallmarks are low albumin and high cholesterol * Hypercoagulable

Question 26

Hypoproteinemia – Inadequate Production - what will we see?

Answer 26

↓ albumin and ↑ globulins * Advanced liver disease <20% functional tissue - not filtering antigens, they end up in lymph nodes, antigenic stimulation of B / plasma cells > not enough liver to make albumin * Cirrhosis, neoplasia, necrosis, inflammation * PSS leading to hepatic atrophy > no materials to make albumin

Question 27

Hypoproteinemia - when do we see just ↓ globulins

Answer 27

* Failure of passive transfer (FPT)

Question 28

Which of the following causes a falsely increased reading in total solids protein (i.e., plasma protein measurement estimate using the refractometer)? 1. Hyperbilirubinemia (icteric plasma) 2. Lipemia 3. Hemolysis

Answer 28

2. Lipemia - yes 3. Hemolysis - moderate to severe hymolysis is associated with a false increase as well

Question 29

Which of the following are causes of hypolipidemia? Select all that apply. A. Hyperadrenocorticism B. Malabsorption/maldigestion C. Hypothyroidism D.Protein losing enteropathy

Answer 29

B. Malabsorption/maldigestion D.Protein losing enteropathy

Question 30

Which of the following are causes of hyperlipidemia? Select all that apply. A. Hypoadrenocorticism B. Hyperadrenocorticism C. Hypothyroidism D. Hyperthyroidism E. Protein losing Nephropathy F. Negative energy balance

Answer 30

B. Hyperadrenocorticism C. Hypothyroidism - Yes, in dogs D. Hyperthyroidism - Yes, in cats E. Protein losing Nephropathy F. Negative energy balance - Yes, often in overconditioned animals that experience a sudden decrease in food intake – decreased beta-oxidation of fats

Question 31

While species differences exist at the fine detail level, what is the general sequence of events in the development of fatty liver? A. Overconditioning > acutely off food > lipid mobilization > hepatocellular lipid accumulation B. Acutely off food > lipid mobilization > overconditioning > hepatocellular lipid accumulation C. Lipid mobilization > hepatocellular lipid accumulation > acutely off food > overconditioning D. Hepatocellular lipid accumulation > lipid mobilization > overconditioning > acutely off food

Answer 31

A. Overconditioning > acutely off food > lipid mobilization > hepatocellular lipid accumulation