Lecture 20 11/21/24 Flashcards
Which glucose monitoring instruments use whole blood as a sample?
-glucometer
-blood gas instrument
Which glucose monitoring instrument uses plasma or serum as a sample?
chem analyzer
Which glucose monitoring instrument uses interstitial fluid as a sample?
freestyle libre style monitors
What are the characteristics of glucose in the blood?
-glucose is dissolved in the aqueous fraction of blood
-cell cytosol contains less water than plasma
-more glucose is found in the plasma than the RBC cytosol
-a given volume of whole blood contains less glucose than the same volume of plasma
What are the characteristics of modern glucometers?
-measure glucose in whole blood
-assume normal PCV and normal distribution of glucose in RBCs and plasma
-covert whole blood glucose to plasma-equivalent glucose via calculation
Why is it important to use veterinary glucometers?
human glucometers have been known to provide falsely low results for animals
When should glucometers NOT be used?
-patients with abnormal PCV; inaccurate results
-effusions; falsely high glucose
What should be done to minimize pre-analytical error?
separate plasma or serum from cells ASAP; separates glucose from the cells that will continue to use glucose until they die
What are the characteristics of glucose on urine dipstick?
-glucose is freely filtered and reabsorbed
-glucosuria can occur if resorption mechanism is overwhelmed or tubular damage/defect is present
What are the mechanisms of hyperglycemia?
-increased intestinal absorption
-catecholamine release
-increased gluconeogenesis/glycogenolysis
-absolute insulin deficiency
-increased insulin resistance
-impaired insulin release
-excess growth hormone
-excess glucagon
-pharmacologic
What are the characteristics of glucose in llamas and alpacas?
-hyperglycemia common when sick
-presumed that hyperglycemia is due to stress hormone release and insulin resistance
-may require insulin treatment, especially with marked abnormalities
What are the mechanisms of hypoglycemia?
-pre-analytical error
-insulin excess
-decrease in insulin antagonists
-decreased gluconeogenesis
-decreased glycogenolysis
-increased tissue utilization of glucose
-pharmacologic
-paraneoplastic
Which patients are predisposed to hypoglycemia during fasting?
-patients undergoing starvation/cachexia
-neonates/juveniles with immature liver
-patients with liver disease
Which ketones are of medical importance?
-acetoacetate
-acetone
-beta-hydroxybutyrate
When are ketones measured?
-as part of routine urine dipstick test
-when diabetes mellitus is suspected
-when negative energy balance is suspected
Which samples are typically used to measure ketones?
-urine
-milk
What is the pathogenesis of ketosis?
-high metabolic energy demand + carb poor diet OR insulin lack/resistance
-fats catabolized for energy
-ketones accumulate
What are the components of ketosis?
-ketonemia
-ketonuria
-ketonlactia
What is the consequence of ketosis?
can lead to titrational metabolic acidosis with a high AG
What are the characteristics of beta-hydroxybutyrate?
-not detected on urine dipstick
-must be measured using a BHB meter or via referral lab
What are the causes of ketosis?
-untreated or poorly regulated diabetes mellitus
-diabetic ketoacidosis
-hypoglycemia of lactation or pregnancy with inadequate carb intake
-endurance athletes with inadequate carb intake
What are the characteristics of ketosis with hyperglycemia?
-think diabetes mellitus
-form of chronic negative energy balance due to insulin lack
-body starves because cells cannot utilize glucose without insulin
-classic findings are PU/PD, polyphagia, and weight loss
-PU/PD due to osmotic diuresis
What are the characteristics of ketosis with hypoglycemia?
-think excess energy demand
-happens when there are inadequate carbs in diet
-occurs with lactational hypoglycemia, pregnancy hypoglycemia, and endurance athletes
What is the pathogenesis of milk fever/parturient paresis in cattle?
-lactation leads to calcium loss
-calcium loss results in hypocalcemia
-hypocalcemia impairs insulin activation
-hyperglycemia occurs
-hyperglycemia can be exacerbated by stress
What is the pathogenesis of lactational hypoglycemia in cattle?
-poor feed quality or decreased food intake during lactation leads to increased tissue demand for glucose
-liver cannot keep up with tissue glucose demand
-hypoglycemia and ketosis occur
What is the pathogenesis of pregnancy hypoglycemia in sheep?
-poor feed quality or decreased food intake when carrying twins leads to increased tissue demand for glucose
-liver cannot keep up with tissue glucose demand
-hypoglycemia and ketosis occur
What are the characteristics of fructosamine?
-protein, typically albumin, irreversibly binds to glucose
-reflects blood glucose over the lifespan of the albumin molecule
-measured in serum
-increased with sustained hyperglycemia
How is fructosamine used in vet med?
-helps determine if hyperglycemia is transient and due to stress or caused by true diabetes mellitus
-used to monitor response to insulin treatment in diabetics
-increased fructosamine suggests prolonged hyperglycemia
What causes increased fructosamine?
persistent hyperglycemia/diabetes mellitus
What causes decreased fructosamine?
-persistent hypoglycemia
-hypoproteinemia/hypoalbuminemia
What are the characteristics of medically important lipids?
-cholesterol, triglycerides, and NEFAs are commonly measured
-no routine tests to measure various lipoprotein classes, such as LDL vs HDL
-increased conc. of lipid in plasma referred to as hyperlipidemia, hyperlipemia, or hyperlipoproteinemia
What are the characteristics of cholesterol?
-cholesterol readout on biochem panel is total cholesterol; HDL + LDL + VLDL
-measured in plasma or serum
-measured in mg/dL
-ideally measured in a fasted sample
What are the characteristics of triglycerides?
triglyceride readout on biochem panel is chylomicron + VLDL
-in fasting sample, TG = mostly VLDL
-in post-prandial sample, TG = mostly chylomicron
-measured in plasma or serum
-measured in mg/dL
-ideally measured in a fasted sample
What are the potential causes of lipemia?
-not fasting patient (error)
-endocrine disease
–idiopathic hyperlipidemia
-pancreatitis
What is the visible appearance of lipemia?
opaque, white, milky plasma or serum
What are the characteristics of lipemia as an interferent?
falsely increases:
-total protein
-hemoglobin
-MCH/MCHC
What are the characteristics of lipemia handling in lab?
-labs prevent lipemia from interfering with sample readouts by running samples through ultrafugation
-need to tell labs not to do ultrafugation when trying to do a medical assessment of tryglycerides
What are the characteristics of the lipemia refrigeration test?
-crude assessment of chylomicron presence
-positive test will have formation of a cream layer
Which disorders always cause hypercholesterolemia?
-cholestasis
-hyperadrenocorticism
-hypothyroidism
-protein-losing nephropathy
Which disorders always cause hypertriglyceridemia?
-acute pancreatitis
-anorexia in obese animals
-diabetes mellitus
-equine metabolic syndrome
-post-prandial
Which disorders cause low cholesterol?
-hepatic insufficiency
-protein-losing enteropathy
-hypoadrenocorticism
-certain cancers
What are the characteristics of NEFAs/FFAs?
-biomarker of negative energy balance
-measured in plasma or serum
-measured in mEq/mL
-typically measured in dairy cattle; increased NEFAs suggests need for better management
