Clinical Chemistry and QA/QC

Quality assurance (QA)

Laboratory procedures that monitor and improve lab performance and minimize errors

• Done through SOPs

• Focuses on preventing the defects at the process level

Quality Control (QC)

• Laboratory procedures that monitor the analytical performance of instrumentation

• Detect analytical errors through commercially available materials

• Focuses on finding the defects of the product itself

Accuracy

• Measured value from analyzer is compared to actual value in the sample

• The closer the measured value is to the actual value the more accurate the result and analyzer are

Precision

• How close measured values are to each other

• The closer repeated measured values in a sample are, the more precise the analyzer is

Reliability

Accuracy + Precision = reliability

Quality control tests what three things?

• Instrumentation

• Reagent

• You

Unreliable diagnostic testing —→

Misdiagnosis and treatment of pt —> compromising pt care

What is clinical chemistry?

• Laboratory tests that evaluate a patient’s overall organ function

What are some of the uses of clincial chemistry?

• Establish base line bloodwork

• Diagnose a disease

• Monitor disease progression

• Monitor response to drug therapy

-“emia”

Indicates the protein, enzyme, or hormone is present in blood

What are some of the available analyzers for clinical chemistry?

• Catalyst ONE

• Vetscan VS2

• Element DCX

• Element DC5X

What clips should you not use a tiger top/serum separator tube for and why?

• DO NOT use for phenobarbital or KBr

• Causes false decrease as gel can absorb drugs

What are the blood tubes that are often used for clinical chemistry?

• Serum separator (tiger top)

• Red top

• Green top

Why should you never force blood into tube via vacuum pressure?

Can cause hemolysis

Why should you remove the serum for a red top quickly after being centrifuged?

• Continual glucose metabolism; false decrease

How long should you let red top and tiger top tubes clot for?

at least 20 minutes

How long and how fast should you centrifuge blood for?

5 minutes at a higher RPM

Why is it important to let the red top and tiger top tubes clot completely?

If tube hasn’t been given proper time to clot fibrin will be present and interfere with the analyzer and amount of sample

What should you do after a sample has been centrifuged?

• Remove serum and plasma asap

• Keep sample refrigerated or frozen until sent to the reference lab

Plasma contains —-

fibrinogen and clotting factors

Serum contains —-

No fibrinogen or clotting factors

Both serum and plasma contain —-

water, electrolytes, proteins, hormones, vitamins, minerals, nutrients, gases, and salts

What is involved in the gross evaluation of serum/plasma?

• Color

  • Hemolysis (red)

  • Icterus (yellow)

  • Lipemia (white and milky)

• Turbidity

Glucose

• A sugar used as an energy source that’s absorbed from the GI tract and transported to the blood

• Basic nutrient for tissues

• Cellular uptake is regulated via insulin

What are some sources of glucose?

• Diet

• Glycogenolysis

• Gluconeogenesis

Glycogenolysis

Glycogen is converted to glucose and readily available as energy

Gluconeogenesis

Glucose production from amino acids and fats

What are some diagnostic tests for glucose?

• Glucometer

• Urine glucose

• Blood glucose

• Fructosamine

Fructosamine

• Sugar bound to albumin (protein)

• Longer half life; BG over the past 2-3 weeks

• Determines if glucose increase is caused by stress or something else

• True hyperglycemia vs. hyperglycemia due to stress or fear

• Libre sensor or glucose curve

Causes of hyperglycemia

• Stress

• Fear

• Typer I and II Diabetes Mellitus

• Hyperadrenocorticism (Cushing’s)

  • Excess cortisol

What type of diabetes is more common in cats vs. dogs?

Type I more common in dogs; Type II more common in cats

Causes of hypoglycemia

• Hypoadrenocorticism (Addison’s)

  • Immune mediated destruction of adrenal glands

• Hypothyroidism

• Neoplasia

• Sepsis

• Liver failure

• Portosystemic shunts

Portosystemic shunts

abnormal vascular connection where blood is not being filtered through the liver and is instead going straight into circulation still containing toxins (needs surgery to fix)

Kidneys

Eliminated waste from the body via urine

Azotemia

excess waste products (urea/creatinine) in the blood

At least —% of nephrons must function appropriately and efficiently

34

Renal disease

renal lesions that cause abnormal function

Renal failure

decreased # of functioning nephrons

• Acute and chronic

• Ischemic event - some sort of disruption of blood flow

• Toxic nephropathy - anti-freeze toxicity

BUN

• Waste product of protein metabolism

• Produces ammonia → liver converts ammonia to urea → excreted by kidneys

• NOT specific for renal disease

Creatinine

• Waste product of muscle metabolism

• More specific evaluation of renal disease than BUN

• Think of body builder → creatine

Isosthenuria

• Inability to concentrate or dilute urine

• Fixed USG (1.008 - 1.012)

Hyposthenuria

• Able to dilute urine

• Unable to concentrate urine

• Unresponsive to ADH (antidiuretic hormone)

Hypersthenuria

• Able to concentrate urine

• Unable to dilute urine

What are the classifications of Azotemia?

• Pre-renal

• Renal

• Post-renal

Pre-renal azotemia

• Before the kidneys

• Dehydration

• Increased protein metabolism

Renal azotemia

• 75% of nephrons are damaged/non-functional

• Inability to adequately concentrate urine

Post-renal azotemia

• After the kidneys

• Think blocked cat and uroabdomen

Total protein

• Measurement of all proteins within the body

• Done via analyzer or refractometer

• Plasma protein vs. serum protein

  • Serum doesn’t contain coagulation proteins or fibrinogen

Causes for hypoproteinemia

• Hemorrhage

• Inflammatory intestinal disease

• Nephropathy causing damage to renal tubules and glomeruli

• Failure of passive transfer

• Decreased production

Causes for hyperproteinemia

dehydration

Albumin

• Protein produced in the liver

• Osmotically active

• Prevents loss of substances through the kidney

Causes of hypoalbuminemia

• Decreased production

• Protein losing nephropathy

• Over hydration

Causes of hyperalbuminemia

• artifact

• administration of corticosteroids

Globulin

• A protein produced in the liver

• Most proteins in the body are globulins

• Involved in immune system or inflammaiton

Causes of hypoglobulinemia

• Hemorrhage

• Protein losing nephropathy

• Decreased production

Causes of hypergloblinemia

• Neoplasia

• Immune/antigen stimulation

Functions of the liver

• Detoxification and excretion

• Digestion

  • Production of bile to digest fat

• Storage

  • Vitamins and iron

• Carbohydrate metabolism

• Fat metabolism

  • Cholesterol and fat synthesis

• Protein metabolism and production

What are the liver tests and are they liver specific?

• ALT - Hepatocellular damage; liver specific

• AST - Not liver specific

• SDH - liver specific

• ALP/ALKP - not liver specific

• GGT - not liver specific

What are the types of bilirubin?

• Unconjugated

  • Not yet processed by the liver

  • Bound to albumin and unable to be excreted via kidneys

• Conjugated

  • Conjugated by hepatocytes making it water soluble and filtered by the glomerulus

• Delta

  • Conjugated bilirubin bound to albumin

  • Cannot be excreted by the kidneys

Bile acids

• Vital for absorption and digestion of fat

• Vital for absorption and digestion of fat-soluble vitamins in SM intestine

• Produced in the liver → secreted in bile → stored in gallbladder

• Think of a fatty meal

  • Animal eats a high fat meal → chemical released and gallbladder contracts → gallbladder releases BAs → BAs removed quickly unless there is an issue

What are two enzymes produced by the pancreas?

1. Amylase

2. Lipase

Amylase

• Not pancreas specific

• Also found in liver, SM intestines, salivary glands, uterus, testes

• Pancreas has highest concentration of amylase

• Enzyme that aids in digestion of sugars

Lipase

• Pancreatic specific

• Enzyme that aids in digestion of fat

Pancreatitis

• Inflammation of the pancreas

• Common and difficult to diagnose

• increase in amylase and lipase when pancreas damaged or injured

What are some clinical signs of pancreatitis?

• V/D

• Ingestion of table scraps, fatty meals, garbage

• Dehydration

• Painful abdomen

• Hazy abdomen seen on radiographs

• Azotemia

What is windrowing

Where cells line up in a parallel fashion depending on the viscosity of the sample

What are some signs of hyperplasia?

• May resemble normal tissue

• Increased numbers

• Increased N:C ratio

• May have binucleation

• “Bluer” cytoplasm

Lack of uniform morphology

pleomorphism

What hormone is released to tell the ovary to start the follicle maturation and what releases this hormone?

FSH; Pituitary

What does progesterone do?

It is released by the ovary to help prepare the uterus for fetal development

What hormone is released which causes the follicle to burst and release the egg and what releases it?

LH; pituitary gland

Parabasal cells

have round shape and stippled nucleus

Intermediate cells

have angular shape and stippled nucleus

Superficial cells

have an angle shape and pyknotic (dense, round, chromatin pattern hard to see) nucleus

Anuclear cells

have an angular shape and no visible nucleus

Best time for breeding occurs when?

Early to mid-estrus

Anestrus predominating cells and length

Parabasal cells, intermediate cells, possibly few WBC, foam cells; several months

Proestrus predominating cells and length

RBCs, few WBCs, parabasal cells, intermediate cells, few superficial; 6-11 days

Estrus predominating cells and length

Mostly superficial, few RBCs; 5-9 days

Diestrus predominating cells and length

Many WBCs, parabasal and intermediate, few RBCs, foam & metestrum cells; 56-60 days

What are the limitations to vaginal cytology?

• Unable to identify the day of ovulation of fertilization

• Cannot be used to determine if pregnancy has occured

• Can’t predict the best day for breeding