chemistry panel Flashcards

Question

What is total protein

Answer 1

ALbumin + globulin = total protein

Answer 2

A/G imbalance is often the first sign of a protein abnormality Can detect increased or decreased albumin or globulin levels Both can be reduced in equal proportions, as with hemorrhage–the ratio will remain unchanged in this case

Answer 3

The A/G ratio is usually >1.00 in dogs, horses, sheep and goats - Albumin>Globulin The A/G ratio is usually <1.00 in cattle, pigs and cats - Albumin

Answer 4

The soluble protein that converts to fibrin to form the matrix of blood clots

Answer 5

Decreased fibrinogen, as seen with hepatic insufficiency, means that the time for clot formation is prolonged or the blood will not clot at all

Answer 6

Acute inflammation in large animals With tissue damage

Answer 7

Metabolism of amino acids,carbohydrates and lipids Synthesis of albumin, cholesterol and plasma proteins (including clotting factors) Digestion and absorption of nutrients related to bile formation Secretion of bile and bilirubin Breakdown and elimination of toxins and drugs

Answer 8

The gallbladder works and sits alongside the liver It’s primary function is to store bile that is produced by the liver

Answer 9

Jaundice Clotting issues Hypoalbuminemia Hypoglycemia Hyperlipoproteinemia Hepatoencephalopathy

Answer 10

There is no single test that can be performed to fully evaluate the liver Diseases of the liver tend to be fairly advanced by the time that they are clinically apparent There are over 100 tests to evaluate the liver

Answer 11

Levels of molecules that the liver produces and metabolizes - Bile acids–hepatic function test - Bilirubin–hepatic function test Molecules that are released when hepatic cells are damaged or with cholestasis (impaired flow of bile) - The major enzymes released from damaged hepatocytes are ALT, AST, ID, GLDH - Enzymes associated with cholestasis are ALP and GGT

Answer 12

Macrophages in the spleen break down hemoglobin→ insoluble bilirubin molecules are released in this process Albumin binds to bilirubin and transports it to the liver Hepatic cells metabolize bilirubin and it conjugates (or binds to) to glucuronide → this will become a component of bile Conjugated bilirubin passes from the liver into the intestine where bacteria convert bilirubin glucuronide to urobilinogen

Answer 13

Urobilinogen is broken down further into urobilin and excreted in feces and urine, or absorbed back into the bloodstream

Answer 14

Prehepatic bilirubin (bound to albumin) makes up about 2/3 of the total bilirubin in serum in most animals

Answer 15

Unconjugated bilirubin is increased when there is an increase in RBC destruction and there are problems with transport or uptake of bilirubin into the hepatocytes

Answer 16

Conjugated bilirubin is increased when there is obstruction of the bile ducts

Answer 17

Assays can measure total bilirubin (conjugated + unconjugated) as well as conjugated bilirubin or unconjugated bilirubin–this will help to determine the cause of jaundice

Answer 18

Bile acids are produced from cholesterol by hepatocytes in the liver They aid in fat absorption and regulate cholesterol levels Bile acids pass into the intestine via the biliary system and are stored in the gallbladder (except in horses) Most of the bile is reabsorbed by the intestine and then processed by the liver, the rest is excreted in the feces

Answer 19

Serum bile acids will be elevated when the hepatocytes, biliary or portal systems are impaired in conditions such as: Chronic hepatitis (viral, bacterial or fungal) Hepatic cirrhosis (due to disease, drugs or toxins) Cholestasis Portosystemic shunts (PSS) Neoplasia

Answer 20

Prolonged fasting/starvation Diarrhea Malabsorptive diseases

Answer 21

Hepatobiliary disease Decreased food intake

Answer 22

Bile acid testing is not a sensitive indicator of hepatic disease in cattle Eating, and sometimes even smelling food stimulates the gallbladder to contract and release bile into the duodenum This will result in an increase in serum bile acids

Answer 23

A serum sample is collected after a 12 hour fast, a subsequent sample is collected 2 hours after a high fat meal is ingested Horses: a single sample is collected

Answer 24

“Leakage enzymes” are enzyme that leak out of damaged hepatocytes Transaminases → catalyze reactions during amino acid production → found in tissues where protein breakdown occurs Alanine transaminase (ALT) Aspartate transaminase (AST) Dehydrogenases → catalyze the transfer of hydrogen during glycolysis Iditol dehydrogenase (ID) Glutamate dehydrogenase (GLDH)

Answer 25

ALT is considered to be a liver specific screening test in dogs and cats When liver is damaged, increased ALT levels are seen within 12 hours, will peak at 24-48 hours and will return to noral within a few weeks For horses, ruminants, pigs and birds, the hepatocytes do not contain enough ALT to be considered “liver specific” (ID is a better test) ALT is also found in the cells of the kidneys, pancreas heart and skeletal muscle, therefore damage to any of those organs will also result in an increase in ALT

Answer 26

ASt is present in cells of the liver, RBCs, heart skeletal muscle, kidneys and pancreas Blood AST levels increase more slowly than ALT levels but return to normal within a day

Answer 27

Hepatic disease Muscle inflammation- strenuous exercise, IM injections or necrosis Hemolysis – spontaneous or artifact → look at the sample Can be correlated with creatinine kinase (CK) to determine if muscle inflammation is likely to be the cause of increased AST in a patient

Answer 28

ID is especially helpful for testing liver damage in larger species such as sheep, goats, swine, horses and cattle (as opposed to ALT) Though ID testing is not readily available in many vet labs ID levels rise quickly with hepatocellular damage or necrosis This enzyme is very unstable in plasma or serum so specimens to be saved, transported or referred out must be frozen

Answer 29

GLDH is found in the highest concentrations in the liver cells of cattle, sheep and goats Elevated levels are indicative of liver damage or necrosis in cattle and sheep

Answer 30

Cholestasis (impaired flow of bile) Metabolic defects in the liver cells With the use of certain medications Due to the action of certain hormones (ex. Corticosteroids, thyroid hormones)

Answer 31

Osteoblasts in bone Chondroblasts in cartilage Intestine, placenta and liver

Answer 32

Increased ALP in large breed puppies is common during bone development: in older animals the bones are no longer growing, therefore increased levels of ALP can be attributed to cholestasis Steroid induction in dogs ALP testing is not useful in cattle and sheep Most often used for dogs and cats

Answer 33

The primary source of GGT is the liver in most animals Blood GGT levels are higher in cattle, horse, sheep and goats than they are in cats and dogs GGT is found in several other organs including renal, biliary and mammary epithelium Elevated GGT levels are suggestive of liver disease, especially obstructive liver disease

Answer 34

Results that are associated with other organs Correlating glucose (pancreas) and liver results Correleting AST to CK (muscle results) History and clinical signs Signalment

Answer 35

Conserve and eliminate water and electrolytes Conserve and eliminate hydrogen to maintain pH balance Conserve nutrients: glucose and protein Eliminate toxins and end products of nitrogen metabolism: urea and creatinine Other roles: blood pressure regulation, regulation of acid secretion in the stomach, regulation of body temperature and platelet aggregation, activation of vitamin D and controlling inflammation

Answer 36

Renin: an enzyme that aids in controlling blood pressure Erythropoietin Prostaglandins: fatty acids that stimulate smooth muscle contraction

Answer 37

Blood enters the kidney via the renal arteries into the glomerulus of the nephron Almost all water and small particles pass into the collecting tubules Each nephron has parts that reabsorb or secrete certain solutes; the amount of solute that the kidney is able to reabsorb is pre-decided → renal threshold Approximately 99% of water is reabsorbed by the kidney, remaining water (excess) is excreted as urine Tests to evaluate kidney function are performed on urine and blood

Answer 38

Azotemia refers to an increase in BUN and creatinine Rarely only one of the two is elevated

Answer 39

Uremia refers to an increase in BUN and creatinine that is severe enough to cause the animal to feel ill Animals will be dehydrated, inappetence and lethargic They may also be vomiting and have diarrhea, have “uremic” oral and/or gastric ulcers and central nervous dysfunction This is seen with advanced renal disease

Answer 40

Pre-renal azotemia–the underlying cause of the azotemia is occurring “before” the kidney

Answer 41

Renal azotemia – the underlying cause of the azotemia is occurring within the kidney

Answer 42

Post-renal azotemia – the underlying cause of the azotemia is occurring “after” the kidney

Answer 43

Dehydration is the most common underlying cause PCV and TP may be mildly elevated Urine specific gravity (USG) will be elevated -the urine is well concentrated because the animal’s kidneys are functioning normally and are conserving water

Answer 44

Can be due to renal failure, congenital disorders, or pyelonephritis Renal failure can be classified as acute or chronic Acute–often very severe, sudden onset, often (but not always) younger animals; may be associated with known toxin exposure Chronic–gradual decrease in renal function and onset of clinical signs

Answer 45

PCV and TP may be elevated if the animal is dehydrated (they often are, especially as the disease progresses) The animal may become anemic with end stage, chronic renal disease due to decreased production of erythropoietin USG will be decreased (the urine will be dilute)

Answer 46

An obstruction in the ureter, neck of the bladder or urethra can cause a post renal azotemia These animals are often dehydrated so PCV and TP will likely be elevated USG will be elevated (the urine is well concentrated)

Answer 47

BUN is the principal end product of aa breakdown in mammals Used to evaluate kidney function due to the kidneys ability to filter urea from the blood Increased BUN does not guarantee an absolute diagnosis of kidney disease

Answer 48

All urea passes through the glomerulus into renal tubules About half of the urea is reabsorbed into the bloodstream and the other half is excreted in the urine

Answer 49

Urea is not transported into the renal tubules as efficiently When the blood exits the kidney back into circulation, there is an increased concentration of urea

Answer 50

Dehydration- urea is insoluble, high volumes of water are needed for its excretion in urine High protein diets or strenuous exercise – leads to an increase in protein breakdown BUN can be evaluated with automated analyzers OR with semi quantitative dipstick – you will perform both of these in the lab

Answer 51

Creatinine is formed from creatine (a component of muscle) as part of muscle metabolism During muscle metabolism, creatinine diffuses out of the muscle cells into body fluids and blood Creatinine levels are influenced by the animals muscle mass

Answer 52

Normally blood creatinine is actively filtered out of the blood and into the renal tubules Any condition that alters the glomerular filtration rate (GFR) will alter the creatinine concentration in the plasma Renal function has to be reduced by almost 75% before blood creatinine levels increase Creatinine alone is not an accurate indicator of renal function

Answer 53

Urea and creatinine are limited in their use for evaluating renal disease because their reference ranges are too wide GFR can be as much as 4 times below normal before changes in urea and creatinine are observed on bloodwork They will both be increased in renal disease Both urea and creatinine are filtered by the glomerulus but the tubular reabsorption of urea can be regulated whereas creatinine stays constant The use of this ratio is not well established in veterinary patients

Answer 54

This is a test that is unique to idexx at this time It can be run at one of the idexx referral labs or on their house analyzers SDMA is a more sensitive indicator of kidney function – it will be increased with as little as 25% loss of renal function It is usually elevated before creatinine and BUN are increased It is a more reliable indicator of a kidney function than creatinine because it is kidney specific

Answer 55

Increased levels may be an indicator that another disease process is affecting the kidneys IRIS guidelines now include SDMA measurements in their criteria for categorising kidney disease

Answer 56

Diseases of the kidney at an earlier stage CKD Acute kidney injury Pyelonephritis Upper urinary obstruction Kidney stones Glomerulonephritis Congenital disease

Answer 57

Other disease processes affecting the kidney Hyperthyroidism Vector borne disease Systemic hypertension Cardiorenal syndrome Lower urinary obstruction Sepsis Neoplasia Drug toxicity

Answer 58

NEW TEST available through idexx for canine and feline patients Crystatin B is a protein that is found within the renal tubular cells When renal tubular cell injury occurs, cystatin B is released into the urine

Answer 59

Increased levels of cystatin B in the urine indicate active kidney injury Able to detect changes earlier than with bloodwork alone Increased ability to recognize subclinical changes Not used to analyze kidney function SDMA, creatinine, BUN and USG are measured to evaluate renal function

Answer 60

Proteinuria may be an indicator of glomerular dysfunction Reference ranges available for canine and feline patients 2mL of urine is collected, ideally by cystocentesis This test can be run by some in house analyzers or sent to a referral lab

Answer 61

UPC ratio <0.2 = Normal UPC ratio 0.2-0.4 (0.2-0.5)= Borderline proteinuric UPC ratio >0.4 (cats), >0.5 (dogs) = Proteinuric

Answer 62

Uric acid is a by-product of nitrogen breakdown In mammals, it is normally converted to allantoin and excreted in the urine Dalmatians–impaired ability to convert uric acid to allantoin so they excrete uric acid in the urine In birds, uric acid makes up 68-80% of the total nitrogen that they excrete in urine With renal disease, serum concentrations of uric acid will increase with >70% loss of renal function

Answer 63

May be performed in patients with azotemia or in those that are showing clinical signs of renal disease in the absence of azotemia There are two primary types of renal clearance tests Effective renal plasma flow (ERPF)–utilizes substances that are eliminated by both glomerular filtration and renal secretion GFR– only uses substances that are eliminated by glomerular filtration Urine and blood are taken at specific times following administration of the test substance

Answer 64

Creatinine clearance tests– endogenous and exogenous clearance tests, iohexol clearance test Single-injection inulin clearance test Water-Deprivation Tests Vasopressin Response Test Fractional Clearance of Electrolytes Inorganic Phosphorus Enzymuria

Answer 65

Require measurement of blood and urine creatinine levels The urinary bladder is catheterized and rinsed out at the beginning and at the end of the test All voided urine is collected for 24 hours

Answer 66

Iohexol is given IV after a 12 hour fast Serum samples are taken 2, 3 and 4 hours after administration and sent to a referral lab for evaluation

Answer 67

The purpose of a water deprivation test is to identify whether or not the kidneys are able to concentrate urine Normally anti-diuretic hormone (ADH aka vasopressin) from the brain signals the kidneys to retain water These tests involve dehydrating the patient to the point where the patient should be secreting ADH to promote water retention, and therefore increasing urine concentration If urine concentration does not increase, this can indicate a lack of ADH, or nephrons that are unresponsive to ADH

Answer 68

PU/PD can be seen with renal disease along with several other disease states Diabetes mellitus and insipidus, Cushing’s disease, psychogenic polydipsia Therefore, the kidneys may be functioning normally, they may not be getting the signal to concentrate urine OR polyuria may be the physiological consequence of polydipsia (as with psychogenic polydipsia) Basic water deprivation test vs. modified water deprivation test

Answer 69

Inulin is excreted entirely by glomerular filtration, therefore it may be the best test for evaluating GFR Inulin is injected IV after a 12 hour fast Serum samples obtained at 20, 40, 80 and 120 minutes after injection to measure inulin concentration

Answer 70

Performed when the patient is not able to concentrate their urine during the water deprivation test Exogenous ADH is given, USG and urine osmolality are evaluated

Answer 71

This is a calculation that describes the excretion of electrolytes (usually sodium, occasionally potassium and phosphorus) relative to the GFR Differentiates pre-renal from post-renal azotemia

Answer 72

Serum Pi is usually the reciprocal of serum Ca Initially, renal damage that alters the GFR leads to decreased urinary Pi and increased urinary Ca Serum Ca and Pi levels are also affected

Answer 73

Refers to the presence of enzymes in the urine Enzymes that may be present in the urine of patients with renal disease include: GGT and NAG which are released from damaged renal tubular cells A comparison of enzyme levels to creatinine can give an indication of the extent of renal damage Renal enzyme levels will increase rapidly after nephrotoxicity occurs

Answer 74

Within the exocrine tissue are small “islands” of cells called islet of Langerhans These make up the endocrine tissue

Answer 75

Alpha cells: almost 20% of the cells in the islets, secrete glucagon and somatostatin Beta cells; ~80% of the cells in the islets, secrete insulin Delta cells: <1% of the cells in the islets, secrete somatostatin Pancreatic polypeptide (PP) cells: <1% of the cells in the islets, secrete pancreatic polypeptide The pancreas has a limited ability to regenerate; when islets are damaged the tissue becomes firm and nodular

Answer 76

Exocrine gland - a gland that secrete products through ducts rather than directly into the bloodstream Amylase and lipase are common enzyme tests to evaluate for pancreatitis Both can be within the normal range in cats with pancreatitis

Answer 77

The primary source is the pancreas, but also found in salivary glands and SI Breaks down scratches and glycogen

Answer 78

Blood amylase levels increase in Acute and chronic pancreatitis Obstruction of the pancreatic ducts Intestinal obstruction/perforation If there is a decrease in GFR, there may be an increase in amylase Amylase that is greater than 3 times the normal range is suggestive of pancreatitis The rise in concentration is not directly proportional to severity of disease

Answer 79

Derived mostly from the pancreas It breaks down the long chain fatty acids of lipids Levels tend to be normal during early stages of pancreatic disease and gradually increase over time In chronic pancreatic disease, damaged pancreatic cells are replaced with connective tissue that is unable to produce enzymes → both amylase and lipase begin to decrease Canine and feline lipase can be tested using ELISA immunologic methods Serum cPL and fPL SNAP tests

Answer 80

Trypsin is a proteolytic enzyme that catalyses the reaction that breaks down proteins Produced exclusively in the pancreas Produced exclusively in the pancreas

Answer 81

Trypsin is readily detected in feces, many tests are performed on fecal samples The absence of trypsin in a fecal sample is abnormal Not commonly used

Answer 82

Serum trypsin-like immunoreactivity (TLI) is an immunoassay test that uses antibodies specific to trypsin and trypsinogen (the precursor to trypsin) to measure levels in the blood Used to diagnose exocrine pancreatic insufficiency (EPI)– levels will be below the normal range in affected animals May be performed with folate and cobalamin (B12) tests as well This test is only available for dogs and cats Overnight fast is required

Answer 83

Endocrine Gland–glands that secrete hormones directly into the circulatory system Blood glucose,fructosamine,β-hydroxybutyrate,serum cholesterol and triglycerides as well as urinalysis provide information about pancreatic function

Answer 84

Pancreatic islets respond directly to blood glucose concentration→they release insulin from the beta cells or glucagon from the alpha cells to regulate blood sugar levels Because only insulin lowers blood glucose levels, if insulin is under-produced or under- performing, it will be clinically obvious Blood glucose levels are the net balance between glucose production (food intake, conversion from other carbohydrates), glucose use and storage Glucose uptake and metabolism depends on insulin and glucagon secretion from the pancreas

Answer 85

If insulin levels are ↑, the rate of glucose absorption into cells for metabolism will ↑ → this will cause blood glucose levels to go ↓ If insulin levels are ↓ (as with diabetes mellitus), glucose is not absorbed into cells→this cause blood glucose levels to go ↑

Answer 86

This test challenges the pancreas and evaluates the effects of insulin A glucose bolus is given and then blood and urine glucose concentrations are monitored If there is adequate insulin production and the cells are responding appropriately, blood glucose levels should peak about 30 mins after glucose administration and return to normal within 2 hours Glucose should not appear in the urine

Answer 87

Diabetes mellitus–prolonged hyperglycemia, glucosuria Hyperactive Beta-cell Tumors– profound hypoglycemia Other concurrent endocrinopathies can affect results This test is rarely necessary to diagnose diabetes mellitus; persistent high blood glucose levels, glucosuria, a history of PU/PD, weight loss, +/- polyphagia are sufficient for diagnosis This test may be used for animals that are borderline hyperglycemic or to differentiate stress hyperglycemia from diabetes mellitus

Answer 88

Fructosamine is formed when glucose in the bloodstream binds to proteins If there is a persistent hyperglycemia,fructosamine levels will be elevated This can be run on some in clinic analyzers or may be a referred out test, fasting is not required This test will give us an indication as to what the blood sugar levels have been doing for the past 2-3 weeks It may be used for long term monitoring of diabetic cats, it can also be used in the diagnosis of suspect cases of diabetes mellitus

Answer 89

A fasted blood glucose sample is obtained, then the patient is injected with a short-acting insulin Subsequent blood glucose measurements are taken at 30 minute intervals for 3 hours If serum glucose fails to drop to 50% of the fasting level within 30 minutes, then it can be concluded that insulin receptors are unresponsive or the insulin is being antagonized Insulin resistance profoundly affects the animal’s therapy and prognosis The patient needs to be monitored closely for signs of hypoglycemia during the test Need to have glucose solution on hand to administer if necessary

Answer 90

Simultaneous measurement of fasting serum glucose and insulin can identify the cause of hyperinsulinemia Hypoglycemia normally inhibits insulin secretion,however, pancreatic beta cell tumors (insulinomas) are hyperactive and unresponsive to glucose and secrete an abundance of insulin Animals with hyperinsulinemia may have a “normal” fasting insulin, but the RATIO is often abnormal

Answer 91

Maintenance of water balance Maintenance of fluid osmotic pressure Muscular and nervous functions Maintenance and activation of several enzyme systems Acid-base regulation

Answer 92

The positive and negative ions found in all body fluids of all organisms

Answer 93

Anions - Chloride (Cl-), Bicarbonate (HCO3-) and Phosphate (PO4-)

Answer 94

Cations–positive ions Sodium (Na+), Potassium (K+), Calcium (Ca2+),Magnesium (Mg2+), Hydrogen (H+

Answer 95

Acid-base balance refers to the steady state of the pH in the body pH describes the hydrogen ion concentration in the body Every change on the pH scale of one number represents a power of ten difference in H+ concentration Normal pH is 7.35-7.45

Answer 96

Acidosis–pH <7.3 → There is an excess of H+ ions in the peripheral blood Alkalosis– pH >7.45→ There is a deficiency of H+ ions in the peripheral blood

Answer 97

In general, normal metabolic processes result in the production of acids (lactic acid, ketoacids, etc) Buffer systems work to counter the buildup of acids by altering the concentration of hydrogen ions

Answer 98

Respiratory→responds in minutes Renal/Metabolic→responds over days

Answer 99

If the blood pH becomes too acidic, bicarbonate binds to excess hydrogen ions → carbonic acid→ breaks down to water and carbon dioxide which is removed by respiration HCO3-+H+ ←>H2CO3 ←>H2O + CO2 The kidneys regulate bicarbonate by reabsorbing or secreting it into the glomerular filtrate in response to the blood pH

Answer 100

K+ and H+ are both positively charged ions that move freely between intracellular fluid (ICF) and extracellular fluid (ECF) A decrease in plasma K+ results in K+ moving out of the cells and into the ECF, H+ moves into the cell → blood pH becomes more alkaline An increase in plasma K+ causes the opposite to occur: extracellular K+ moves into the cell and H+ moves out→ blood pH becomes more acidic

Answer 101

Proteins bind and release H+ions Hemoglobin has the ability to bind CO2 and H+ CO2 is transported to the lungs and exhaled

Answer 102

by the cause of the condition Metabolic acidosis Metabolic alkalosis Respiratory acidosis Respiratory alkalosis

Answer 103

The imbalances are inter-related If a pH imbalance occurs, the respiratory and renal systems will work to correct the abnormality Any condition that results in an accumulation of acids in the body leads to a metabolic acidosis Ketoacid production due to DM→Decreased HCO3- → Metabolic Acidosis Abnormal electrolyte concentrations and loss of acid d/t vomiting → Increased relative HCO3- → Metabolic Alkalosis

Answer 104

Increased or decreased dietary intake Shift of ions between intra- and extracellular fluid Renal loss or retention Gastrointestinal malabsorption Respiratory system *Lipemia and hemolysis can affect electrolyte measurements *Arterial samples are ideal for analysis of blood gases; must be analyzed quickly after collection because room air affects the concentration of dissolved gases and sample pH

Answer 105

Sodium Potassium Calcium Magnesium Hydrogen Chloride Bicarbonate Inorganic Phosphorus

Answer 106

Chemistry panels measure the ions and compounds present in the serum/plasma ONLY, it does not measure the concentration of these products within the cells With EXTRACELLULAR ions → hemolysis will dilute the sample causing ion levels to be artificially low With INTRACELLULAR ions → hemolysis will cause ions to be released into the extracellular fluid thereby artificially increasing ion levels

Answer 107

The major cation of plasma and ECF It’s main function is water distribution and maintenance of body fluid osmotic pressure Sodium is filtered by the kidney and reabsorbed back into the body as needed in exchange for H+ Vital role in the pH regulation of urine and acid-base balance

Answer 108

increased blood sodium concentration Seen with water deprivation, hyperventilation, osmotic diuresis

Answer 109

decreased blood sodium concentration v/d, ketonuria, hypoadrenocorticism, CHF

Answer 110

The major intracellular cation Important for muscle function, respiration, cardiac function, nerve impulse transmission and carbohydrate metabolism

Answer 111

increased blood potassium concentration This may be seen with cellular damage, acidosis (K+ is exchanged for H+ to buffer pH), urinary tract obstructions

Answer 112

decreased blood potassium concentration Due to low intake, alkalosis, fluid loss d/t v/d, ketonuria, diuresis

Answer 113

Both extremely high and extremely low potassium levels can cause fatal cardiac arrest due to an abnormal heart rate Plasma samples are preferred over serum samples as platelets can release K+ during the clotting process– however analyzer type may dictate sample requirements If the sample is going to be refrigerated, the plasma should be separated from the cells – refrigeration will cause K+ to move from the ICF to the ECF

Answer 114

Chloride is the predominant extracellular anion It maintains water distribution, osmotic pressure, normal anion/cation ratio Closely related to sodium and bicarbonate levels Hyperchloremia– increased blood chloride concentration Hypochloremia– decreased blood chloride concentration If the sample is to be stored, serum/plasma should be separated from the cells to prevent artificial reductions in Cl- concentrations

Answer 115

The second most common anion in plasma The kidneys work to regulate bicarbonate levels by excreting excesses after it reabsorbs what is needed from the urine Bicarbonate levels are commonly estimated (not directly measured) from blood CO2 levels– this is done by a blood gas analyzer or as part of an electrolyte panel on a chemistry analyzer

Answer 116

2nd most common intracellular cation Found in all body tissues, more than 50% is found in bones Works closely with calcium and phosphorus Activates enzyme systems, involved in making and breaking down acetylcholine (a neurotransmitter) Imbalance of magnesium/calcium ratio can result in muscle tetany because of the release of ACh Cattle and sheep are the only domestic animals to show clinical effects of magnesium deficiencies

Answer 117

Hypermagnesemia– increased blood magnesium concentrations Hypomagnesemia – decreased blood magnesium concentrations

Answer 118

More than 99% of calcium is found in bone The remaining 1% helps to maintain enzyme activity, plays a role in blood coagulation, neuromuscular excitability and tone (decreased calcium can also result in muscle tetany), and maintenance of inorganic ion transfer across cell membranes Calcium is inversely related to phosphorus, if one goes up, the other goes down

Answer 119

Hypercalcemia– increased blood calcium concentration Hypocalcemia – decreased blood calcium concentration Very tightly regulated

Answer 120

80% of phosphorus is found in bones The remaining 20% serves to store, release and transfer energy, is involved with carbohydrate metabolism and is used to produce nucleic acids and phospholipids Within serum/plasma, phosphorus is in an inorganic form Within RBCs, it is in an organic form DO NOT USE HEMOLYZED SAMPLES – falsely elevated results Separate the cells from the serum/plasma ASAP

Answer 121

Hyperphosphatemia– increased serum phosphorus levels Hypophosphatemia – decreased serum phosphorus levels

Answer 122

Normally, the total number of cations EQUALS the total number of anions This neutrality is maintained by the various buffering systems Any difference between positive and negative charges is called the anion gap Chiefly used to identify metabolic acidosis

Answer 123

(Na+ + K+) –(Cl-+HCO3-) = ANION GAP

Answer 124

Dogs: 12-24mEq/L Cats: 13-27mEq/L Increased anion gap: lactic acidosis, renal failure, diabetic ketoacidosis Decreased anion gap: often due to hypoalbuminemia →the proteins required to transport bicarbonate are lacking

Answer 125

CK is an enzyme found predominately in striated muscle cells and to a lesser extent, the brain When skeletal muscle (namely cardiac) is damaged, CK leaks out of the cells and results in elevated CK in the peripheral blood CK is frequently tested if an animal has an elevated AST but shows not symptoms of liver damage If the CK is also elevated, it would suggest a muscular issue (possibly cardiac related) It is also elevated in CSF with non-specific damage to neural tissue (hypoxia, trauma, inflammation, space-occupying tumors) CSF CK can also be useful prognostically in canine neurological cases and premature foals

Answer 126

Seizures Intramuscular injections, repeated attempts at IV blood draws Surgery Vigorous exercise Electric shock Lacerations Bruising Hypothermia Persistent recumbency Myositis and myopathies Essentially anything that damages the cell membranes... A delay in testing may cause an increase in reported CK levels

Answer 127

Lactate, or lactic acid, is produced by anaerobic cellular metabolism Increased lactate indicates hypoxia or hypoperfusion Lactate can be analyzed in plasma, CSF and peritoneal fluid

Answer 128

Blood/peritoneal fluid analysis is a diagnostic aid in equine colic cases In healthy horses, the blood lactate is always higher than in the peritoneal fluid If horses have a GI disorder such as an impaction or torsion, the peritoneal fluid lactate will be higher than the blood lactate levels Collect sample in fluoride oxalate or lithium heparin tubes Hand held lactate meters are available

Answer 129

There are a variety of endocrine organs and tissues that produce and release hormones directly into capillaries These include the adrenal glands, thyroid and parathyroid glands and the pituitary gland

Answer 130

Stressors cause the hypothalamus to secrete corticotropin - releasing hormone (CRH) → causes the anterior pituitary to secrete adrenocorticotropic hormone (ACTH) → stimulates adrenocortical growth and secretion Cortisol is an important hormone that is secreted by the adrenal gland in mammals Cortisol inhibits both CRH and ACTH release

Answer 131

Hyperadrenocorticism/Cushing’s Disease Excessive cortisol release It is caused by: Brain/pituitary tumors Idiopathic hyperplasia of the adrenal glands Neoplasia of one or both adrenal glands Over- enthusiastic use of glucocorticoids

Answer 132

Hypoadrenocorticism/Addison’s Disease Reduced cortisol release May be caused by: Adrenal atrophy Autoimmune disease Neoplasia Medications

Answer 133

An ACTH stimulation test may be requested for animals presenting with suspected hyper- or hypoadrenocorticism This test evaluates the adrenal glands response to the administration of ACTH The degree of glucocorticoid production is expected to be proportional to the adrenal gland’s size and development Hyperplastic (cell proliferative)–exaggerated adrenal response Hypoplastic (atrophied)– decreased adrenal response This test can be used to detect abnormalities but not the underlying cause Also used to evaluate the efficacy of therapy

Answer 134

Cortisol levels are tested before and after ACTH administration Accuracy in diagnosing hyperadrenocorticism with this test is about 80% in dogs and 50% in cats Used to evaluate response to mitotane or trilostane therapy Clinical signs of Cushing’s Disease PU/PD, panting, polyphagia, pot-bellied abdomen, altered fat distribution, alopecia, mild muscle weakness, lethargy Fragile skin syndrome in cats

Answer 135

Cortisol levels are tested before and after ACTH administration The adrenal glands are unable to respond to the ACTH so post-ACTH cortisol levels are below the normal range Clinical signs of Addison’s Disease Depression, lethargy, lack of appetite, weight loss, v/d, bloody stools, weakness, dehydration and bradycardia

Answer 136

Low Dose Dexamethasone Suppression Test (LDDST)–can confirm a diagnosis of Cushing’s disease or can be used in the place of the ACTH stim test to diagnose Cushing’s disease High Dose Dexamethasone Suppression Test (HDDST) – used to differentiate between pituitary causes of hyperadrenocorticism from adrenal causes Dexamethasone is a potent glucocorticoid that suppresses ACTH release

Answer 137

Adrenal dependent–no cortisol suppression at 4 or 8 hours post dexamethasone Pituitary dependent–cortisol suppression at 4+/- 8 hours post dexamethasone

Answer 138

Adrenal dependent – no cortisol suppression Pituitary dependent– cortisol suppression

Answer 139

Dexamethasone is administered IV, ACTH is then administered by the IV route 4 hours later Cortisol levels are measured before dexamethasone administration, before ACTH administration and after ACTH administration

Answer 140

Increased cortisol after dexamethasone and ACTH Stim – Hyperadrenocorticism Increased cortisol after dexamethasone and NORMAL after ACTH stim – hyperadrenocorticism Increased cortisol after dexamethasone and VERY HIGH after ACTH stim – pituitary hyperadrenocorticism

Answer 141

Urine Cortisol/Creatinine ratio – used as a screening tool to rule out Cushing’s disease If the ratio is low – it is very unlikely that the animal has hyperadrenocorticism If the ratio is elevated, further testing needs to be done to confirm a diagnosis of hyperadrenocorticism

Answer 142

Tends to occur in older horses Due to adenomas of the pars intermedia of the pituitary gland Clinical signs include: PU/PD, polyphagia, muscle weakness, excessive sweating, long hair coat (fail to shed) Lab findings include: hyperglycemia and glucosuria (likely due to insulin resistance) Diagnosed with an overnight dexamethasone suppression test Insulin and anti-adrenocortical medications are not useful, dopamine antagonists may be helpful

Answer 143

Thyroid hormones influence the metabolic rate, growth and differentiation of cells

Answer 144

Thyrotropin-releasing hormone (TRH) from the hypothalamus stimulates the anterior pituitary to release thyroid stimulating hormone (TSH) TSH enhances thyroid gland growth, function and release of thyroxine which is produced in two forms T3 (triiodothyronine; the more active form) T4 (thyroxine; can convert to T3 in tissues) Thyroxine inhibits TRH and TSH release

Answer 145

Hypothyroidism: Dogs, horses, ruminants and swine Hyperthyroidism: Cats This may be attributable to dietary iodine imbalances or exposure to goitrogens in large animals

Answer 146

Clinical signs–spontaneous abortion, stillbirths, alopecia, goiter in fetuses Serum T4 concentrations Protein bound iodine levels in serum Pasture iodine analysis– the feed may be analyzed for goitrogenic plants or for excess calcium (which decreases iodine uptake) A primary glandular disease due to neoplasia, autoimmune disease or idiopathic atrophy is much more common than pituitary disease

Answer 147

Insulin and estrogen increase T4 Glucocorticoids, anticonvulsants, penicillin, trimethoprim sulfamethoxazole (TMS) and others decrease T4

Answer 148

measuring free T4, +/- TSH levels Hypothyroid: low free T4 and elevated TSH Hyperthyroid: elevated free T4

Answer 149

Substances that disrupt the production of thyroid hormones, interfering with iodine uptake in the thyroid gland Brassica spp This triggers the release of TSH from the pituitary gland and promotes the growth of thyroid tissue → GOITER

Answer 150

In horses, iodine- deficient hypothyroidism is rare since iodized salt is available However, overzealous iodine supplementation can actually provoke hypothyroidism and goiter because the excessive use of iodine can actually inhibit thyroid function!!

Answer 151

T3 – less reliable than free T4 Total T4 (TT4) – will also measure anti-thyroid hormones so not as reliable as a free T4 Thyroglobulin autoantibody test – canine specific test, used to detect autoimmune thyroiditis Thyroid stimulating hormone response test: primarily used for research purposes at this time

Answer 152

Elevated growth hormone (GH), produced by the pituitary gland, will cause canine acromegaly Serial assays of GH are tested because dogs with acromegaly will show a constant level of GH In a normal dog, the GH levels will fluctuate

Answer 153

The principal function of the GIT is to digest and absorb nutrients and excrete waste products GI diseases are common in animals, so specific testing and diagnosis is important Biopsy is may be required to arrive at a definitive diagnosis; function tests rule out other diseases and confirm the need for more invasive procedures Maldigestion → due to altered gastric secretion or reduced digestive enzymes (from the pancreas and to a lesser degree the small intestine) Approximately 90% of the pancreas needs to be non-functional before clinical signs become apparent Malabsorption→ often caused by disease of the small intestinal wall or bacterial overgrowth syndromes A loss of function of >50% of the small intestine in dogs will result in “short bowel syndrome”

Answer 154

Blood loss into the gut may be apparent as either melena or hematochezia depending on where the bleeding is occurring within the GIT If blood loss is less severe, it may not be apparent by gross examination of the feces If blood loss into the GIT is suspected, a fecal occult blood test can be run This test will produce a color change if it comes into contact with hemoglobin or myoglobin Small animals will need to be fed a meat free diet for up to 3 days prior to testing Ensure large animals are not being supplemented with meat or bone meal

Answer 155

d-Xylose is absorbed in the SI and eliminated unchanged in the urine This makes it relatively easy to trace Primarily performed in horses, can also be used in dogs Not useful in ruminant species–rumen flora interfere with results Xylose is given orally and serial blood concentrations are measured every 30 minutes for 4-5 hours Abnormal test results suggest a malabsorptive problem in the SI Vomiting and ascites will decrease xylose blood concentrations Renal disease will lead to an increase xylose blood concentrations

Answer 156

B vitamins that are reduced in animals with malabsorption issues Folate is absorbed in the proximal intestine, while cobalamin is absorbed in the ileum Bacterial overgrowth may cause folate levels to increase and cobalamin levels to decrease Often evaluated in conjunction with TLI Overnight fast required prior to blood sampling

Answer 157

Samples for toxicology are usually sent out to a reference lab Fluids, tissues and feed must be sent in separate, clean, leak-proof, hard, plastic containers Samples must be individually identified with the owner’s and veterinarian’s names, animals name/ID number and specimen type Samples can include serum/plasma, urine, feces, feed, water, suspicious bait, stomach contents (in the form of vomit, gastric lavage or post mortem collection)... Blood samples are best kept refrigerated, gut contents may be frozen Samples may also include necropsy or biopsy tissues→ they should be placed in a 10% formalin solution in a 10:1 formalin to tissue ratio May become a legal issue!!!

Answer 158

Fairly common environmental pollutant–found in old paint, ammunition, car batteries, solder, linoleum, petroleum and roofing products “Plumbism”, lead poisoning can occur in all species, clinical signs are related to the GIT and nervous systems Hematology examination may exhibit basophilic stippling of RBCs and increased nucleated RBCs without anemia There will not be any specific changes on the chemistry panel Blood collected in EDTA, heparin or citrate may be analyzed for lead at a reference lab Feces, liver, kidney, or bone can be analyzed for the presence of lead

Answer 159

Most common in ruminants, pigs, and horses that ingest feeds containing high concentrations of these compounds Excessive levels may be found in cereals, grasses and root crops that have been heavily fertilized with nitrogenous compounds Water may contain large quantities of nitrate Nitrates are converted to nitrites in the feed or the GIT; nitrites absorbed from the gut decrease the oxygen-carrying capacity of the RBCs by degrading hemoglobin to methemoglobin → the animal’s blood becomes dark red to brownish in color A dilute diphenylamine solution may be used to test for nitrites in feed, serum/plasma, urine and body fluid samples → if nitrates or nitrites are present in the sample, it will turn blue immediately Hemolysis may mask the color change

Answer 160

These are chemicals that are designed to kill rodents They work by inhibiting the metabolism of vitamin K Vitamin K is needed for the production of clotting factors (II, VII, IX and X) in the liver Affected animals will have a prolonged prothrombin and partial thromboplastin time as blood clotting is impaired A presumptive diagnosis is made based on routine coagulation testing and patient response to vitamin K therapy

Answer 161

Ingestion results in oxidative damage to RBCs → Heinz bodies are formed Horses–Red Maple leaves Cattle–Brassicaspp Dogs–Onions Cats–Acetaminophen Selenium deficient animals are more prone to oxidative injury

Answer 162

Commonly causes accidental poisoning that can lead to a fatal toxicosis in dogs and cats A diagnosis can be presumed based on urinalysis and the observation of a high concentration of calcium oxalate monohydrate crystals 5mL (one teaspoon) can kill a cat, 15mL (one tablespoon) can kill a medium-sized dog The formation of urinary crystals causes irreversible kidney damage Ethylene glycol → Glycolic acid → Oxalic acid crystals

Answer 163

Clinical signs vary significantly depending on the drug that was ingested Drugs can be medicinal or illicit Keep in mind that owners may not want to disclose if their animal may have accidently ingested illicit drugs It is always the room mate’s fault!! Rapid screening tests are available for drugs of abuse, typically include THC, opioids, cocaine, meth Also, illicit drugs may contain other drugs or stimulants as they are unregulated