Practical Clinical Pathology - PowerPoint Presentation

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Practical Clinical PathologyIn House Lab Tests

Wendy Blount, DVM

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EmergencyQuick Assessment

Immediate: PCV/TP, glucose, BUN

Get samples to run laterBlood (8-10cc)EDTA tube (2-3cc)

Lithium heparin tube (2-3cc)Potassium citrate tube (2-3cc)Red top clot tube (2-3cc)

urine

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EmergencyQuick Assessment

Urinalysis

If you need a urinalysis later, you need a sample prior to fluid therapy, before specific gravity is dilutedIf fever, you may want urine for possible culture prior to antibiotic therapyUse a 5-8Fr x 36” infant feeding tube to catheterize male dog > 75 pounds

Use US guidance if needed for cystocentesis of small bladder

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EmergencyQuick Assessment

Indications for Diagnostic Abdominocentesis

Palpable fluid waveOwner reports abdominal bloating

Suspect abdominal hemorrhageAcute collapse, pale mucous membranes, weak pulses, low blood pressure, + anemia

Suspect peritonitis – shock and abdominal painFluid seen on AFAST®

ultrasound

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EmergencyQuick Assessment

Diagnostic abdominal tap technique

4 quadrants - R cranial, L cranial, R caudal, L caudalDiagnostic Peritoneal Lavage

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EmergencyQuick Assessment

AFAST

® TechniqueHR site – half way between umbilicus and table (R lateral)

20-22g 1-1/2 needle or butterfly

no syringe – gravity drip into tubes

Put fluid in EDTA and red top tubes for analysis

EDTA - Spin

down

& direct for

cytology

red

top tube for culture if

needed (closed - syringe)

Run EDTA through CBC machine for cell

counts

Fluid Analysis

Handout

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AscitesTransudate or Modified Transudate

Remove enough fluid to alleviate dyspnea, and allow comfortable chest x-rays & abdominal ultrasoundBloodwork and abdominal ultrasound to determine the cause, and treat accordingly

If cause is congestive heart failure, remove all fluidHemorrhage - usually a surgical problem, unless

Coagulopathy or anaphylaxis is identified and treated

Traumatic hemorrhage resolves spontaneously (serial AFAST®), + auto-transfusion

Non-septic exudate, chyle – tap if dyspneic

Rarely surgical

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Ascites

Septic exudate, uroabdomen, bile peritonitis – usually surgicalMultiple species of bacteria suggest GI perforationPlant material is very strong evidence

If no bacteria are seen, look for phagocytosed bacteria in WBC, and for toxic changes in the neutrophilsFeline Infectious Peritonitis (FIP) fluidHigh protein – mucoid strings (TP > 5-10 g/dl), yellow

Cell count usually <5,000/ul & almost always <10,000/ulMononuclear cells usually > segs

Albumin:glob usually <0.8: <0.45 is strong evidence

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Ascites

Compare abdominal fluid to plasma/serumAbdominal amylase and lipase > plasma/serumPancreatitis

Abdominal fluid glucose <50 mg/dl and <plasma/serumoften indicative of bacterial peritonitis

Abdominal bilirubin > plasma/serumGallbladder/biliary tract rupture

Abdominal creat > plasma/serum (BUN the same)Ruptured urinary tract Abd. triglycerides > serum; Abd. Cholesterol < serum

chyle

Abdominal coronavirus PCR or AB titer >> serum

FIP

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HypoadrenocorticismPrimary hypoadrenocorticismFailure of adrenal glands to make glucocorticoids and/or mineralocorticoids

Secondary hypoadrenocorticismFailure of the pituitary to make ACTH

Atypical hypoadrenocorticismHypoadrenocorticism with failure to make glucocorticoids only (electrolytes are normal)

Usually primary, but can also be secondary

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Primary HypoadrenocorticismCBCNormochromic, normocytic mild anemia

Lack of stress leukogram in a sick animal

Serum PanelHyperkalemia, hyponatremia, hypochloridemiaNa:K < 27

Azotemia (increased BUN, creat, phos)Metabolic acidosis

Mild hypercalcemia (12-14 mg/dl)Mild to moderate hypoglycemia (45-60 mg/dl)Mild to moderate hypoalbuminemia

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Primary HypoadrenocorticismUrinalysisUrine SG varies from hyposthenuric to mildly concentrated (<1.025) – 20% PU-PD

Endocrine Testing

ACTH stim – baseline and post-ACTH <2Endogenous ACTH high

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Primary Atypical HypoadrenocorticismSame CBC as Primary HypoadrenocorticismAzotemia less severe than with primary

Mild hypercalcemia less likely than with primaryMild hypoglycemia (45-60 mg/dl) – same

Mild to moderate hypoalbuminemiaMetabolic acidosis – same

Urine SG varies from hyposthenuric to mildly concentrated (<1.025) - same

Na, K, Na:K normal (27-40)High Endogenous ACTH

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Secondary HypoadrenocorticismResembles primary atypical hypoadrenocorticism, except:endogenous ACTH is low

Adrenals atrophy, but ZG is sparedElectrolytes are normal

Secondary hypoadrenocorticism is almost always atypical

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The Great PretenderHypoglycemia and Addison’sGlucocorticoids increase gluconeogenesis while decreasing glucose use in tissues via increase insulin receptor sensitivity

May be more common in toy breeds where there are other predispositions to hypoglycemiaCan be severe enough to cause seizures

20-25% of Addisonians are hypoglycemicResponds the therapy in 24-48 hours

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Blake FoskeyOrange TX

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The Great PretenderAzotemia and Addison’sHypovolemia causing decreased renal perfusion and prerenal azotemia (not enough sodium)

Can result in renal injury and renal azotemia if severe, prolonged and untreatedHemorrhage in the GI tract can result in increased BUN

GI bleeding leads to more ammonia in the colonAmmonia converted to urea in the liver

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The Great PretenderAzotemia and Addison’sIf no renal injury, azotemia responds quickly to fluid therapy – but relapses

Responds even better if DexSP given for shock Urine specific gravity

Often mildly concentrated urineCan also be isosthenuric or hyposthenuric due to medullary washout (20% PU-PD)

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The Great PretenderHypercalcemia and Addison’sMore likely in Addisonians with more severe disease and hyperkalemia

29% of primary Addisonians are hypercalcemicMechanism – unsure

Possible hemoconcentrations of calcium binding serum proteinsDecreased renal clearance of calcium

Cortisol antagonizes vitamin DResponds rapidly to therapy

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Na:K RatioAldosterone deficiency (mineralocorticoid) makes it impossible for the kidneys to conserve sodium or excrete potassium properlyCortisol deficiency precludes NaK-ATPase pump from maintaining proper Na-K balance

Intracellular potassium decreasesIntracellular sodium increases

Acidosis due to hypovolemia further exacerbates Na-K imbalanceAs H

+ moves into cells, K+

moves out

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Na:K RatioThumb RulesAdrenal (primary) Addison’s

86% have hyponatremia (<142 mEq/L)95% have hyperkalemia (>5.5 mEq/L)

4% have normal K, Na and ClACTH deficiency (secondary HypoAC)

35% have hyponatremiaUnlikely to cause hyperkalemia

Clinical glucocorticoid deficiencyDehydration can mask low Na and Cl

Addisonians almost never have low potassium or high sodium

Decreased Na:K is highly specific but not sensitive at all for Addison’s disease

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Na:K RatioMike Willard was amongst the earliest veterinary authors to embrace Na:K <27-28 as a diagnostic method for Addison'sMike Willard, 2005 – personal conversation

“I wish I had never written that paper”

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Na:K RatioRoth et al 1999, J Vet Diagn InvestEvaluation of low sodium:potassium ratios in dogs.

Although numerous conditions were associated with a low Na:K ratio, renal disease was the most common.

Hypoadrenocorticism was present in only 13% of dogs with Na:K ratios between 24 and 15 but was present in all

dogs with Na:K ratios <15.

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Na:K RatioPak 2000, J Vet ScienceThe clinical implication of sodium-potassium ratios in dogs.

Although there have been substantial evidences on the usefulness of electrolytes for the diagnosis of disease, the evidences for a direct link between serum sodium and serum potassium in relation to a specific disease are very limited.

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Na:K RatioWillard 2005, Vet Clin PathDecreased sodium:potassium ratios in cats: 49 cases

“CONCLUSIONS: Decreased Na:K ratios frequently occur in cats with diseases other than hypoadrenocorticism, including cats with effusions. These findings should be considered when evaluating cats with this biochemical abnormality.

”

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Na:K RatioAdler et al. JAVIM 2007Abnormalities of serum electrolyte concentrations in dogs with hypoadrenocorticism.

Most Addisonians with both gluco- and mineralocorticoid insufficiency have Na:K ratios of 27-28 or less. In dogs with a Na:K ratio of 24 or less, the likelihood of confirming a diagnosis of HA with an ACTH stimulation test is high.

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Na:K RatioNeilsen et al, Vet Record 2008Low ratios of sodium to potassium in the serum of 238 dogs.

Hypoadrenocorticism was the single most common cause of a low Na:K ratio27 (16.7%) of the cases.

Other clinical problems associated with low Na:K ratios included different urogenital, cardiorespiratory and gastrointestinal diseases (83.3%).

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Na:K RatioConclusionsThere are many causes of Na:K < 27-28

Only 15-17% of these are AddisonianOther causes include:

Abdominal or thoracic effusionCardiorespiratory disease

AcidosisTrauma or reperfusion injury

SepsisDiabetic KetoacidosisUremia (oliguric renal failure, obstruction/rupture)

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Na:K RatioConclusionsOther causes include:Liver failure

ToxicityMushrooms, IV fluid therapy or TPN, K sparing diuretics (spironolactone), ACE inhibitors, NSAIDs

ArtifactsExtreme leukocytosis

Hemolysis in Akitas and Shiba inusRunning serology on EDTA plasma

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Na:K RatioConclusionsOther causes include:

GI diseaseWhipworms, hookworms

PancreatitisGDV

ulcers, especially if perforationCanine parvovirus

Canine distemper virussevere malabsorptionSevere deep pyoderma

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Na:K RatioConclusions – The Bottom LineMost Addisonians that lack both gluco- and mineralocorticoid deficiencies have Na:K <27

Na:K <24 is a stronger indicator of primary hypoACNa:K <15 is even stronger

Na:K >28 makes primary Addison's unlikely

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Hyperadrenocorticism

CBCMild normocytic, normochromic anemia

Hemolysis of severe and advancedStress leukogram

Serum PanelIncreased ALKP > ALT (dog > cat)Hyperglycemia

75-85% of cats & 5% of dogs are diabeticHigh cholesterol

High triglycerides

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Hyperadrenocorticism

UrinalysisUrine SG <1.025, proteinuria

urinary tract infection (20%), and half of those have no symptomsUrine sediment may show bacteria without inflammation

Endocrine TestingDogs – secondary hypothyroidism

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HypothyroidismCBCNormochromic, normocytic anemia (PCV 30-35%)Serum PanelHigh cholesterol

High triglycerides (lipemia)Mild hypercalcemia with cretinism

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HyperthyroidismCBCNormal to mild increase in PCV (40-50%) & MCV (20%)Heinz bodies, Enlarged plateletsSerum PanelIncreased ALT, ALKP (75% both, 90% one)

Stress hyperglycemiaAzotemia (10%)CRF is estimated to be present in 15% of cats older than 15 years25-50% of non-azotemic cats with hypertT4 will become azotemic after

treatment

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HyperthyroidismUrinalysisKetonuriaIncreased ammoniaNormal bile

acids Cortisol high (serum & UCC)Fructosamine lowIncreased PCV or low fructosamine should trigger TT4/fT4 in

geriatric cat

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PancreatitisCBC – nonspecificThrombocytopeniaNeutrophilia with left shift

Anemia

SerologyLipemia after a prolonged fast (TG, chol)Lipemia in the cat is rare, and should prompt ruling out pancreatitis

Hypocalcemia – why?

Calcium consumed by saponification of fatRelative hypocalcemia due to hypoalbuminemiaHypoalbuminemia – why?

Massive inflammation, vasculitis, SIRS,

(

+

sepsis)

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PancreatitisSerology – Dogs and CatsNonspecific changes

Elevated liver enzymesElevated bilirubin

Azotemia

Hyperglycemia (cause or effect)Hypoglycemia

Hypophosphatemia – why? acidosisHypochloridemia – why?

vomiting

Amylase seldom helpful, lipase a weak indicator

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PancreatitisSerology – Dogs onlyAmylase

normal in 47%Lipase

Normal in 61%

Serology – Cats onlyElevated cholesterol (less often than triglycerides)Amylase and lipase not at all useful

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PancreatitisGI Serology – Dogs and Cats - http://

vetmed.tamu.edu/gilab/research/cobalamin-informationSC once weekly for 6 weeks, then every 30 days, or as indicated by

monitoring<10 lbs – 250 mcg10-20 lbs – 400 mcg

20-40 lbs – 600 mcg60-80 lbs – 1000 mcg

80-100 lbs – 1200 mcg>100 lbs – 1500 mcgPO daily x 30d, then as indicated by monitoring DOGS

<20 lbs – 250 mcg, 20-40 lbs – 500 mcg, >40 lbs – 1000 mcg

Cobalequin®

- Nutramax Lab

ACVIM 2015

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PancreatitisWhat is the BEST blood test to diagnose pancreatitis??cPLI

(canine Pancreatic Lipase Immunoreactivity)97% sensitive for pancreatitis

82% specific for pancreatitis (18% false positives)fPLI (feline Pancreatic Lipase Immunoreactivity)

Low confidence in this test amongst some feline specialists100% sensitive for severe pancreatitis, 54% for mild

100% specific in healthy cats, 67% specific in sick catsMuch more sensitive and specific for pancreatitisthan any other blood test or imaging in dogs

Antech and IDEXX

TAMU GI Lab (TVMDL sends to TAMU)

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Diagnostic tools: A comparison

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SNAP

R

cPLTM

Features

Reference

Sample

2 results: Normal or Abnormal

Read time: 10 minutes

Storage: Refrigeration

Sample type: Serum

Read: Visual; semi-quantitative

<200 ug/L normal

200-400 ug/L borderline

>400 ug/L pancreatitis

Correlation to cPLI >95%

96% of interpretations are correct

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Comparing Spec cPL values to SNAP results

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Dog w/ Vomiting, Anorexia, Abdominal pain CBCProfile/lytesUA

SNAP cPL

SNAP Abnormal

Treat, Monitor, Retest; Continue to rule out other differential diagnoses

SNAP NormalPancreatitis is unlikely – pursue other differential diagnoses

SNAP cPL for Screening

Treat for pancreatitis,

Baseline cPLI

Abdominal radiographs

Abdominal US

Baseline cPLI

monitor w/ cPLI

200-399

>400

US/Rads confirm

pancreatitis

Treat for pancreatitis,

Monitor with cPLI

US/Rads equivocal

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Dr. Mike WardNacogdoches TX

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PancreatitisUrinalysis – nonspecificKetones

think diabetic with ketoacidosis (if glucosuria)Or prolonged fasting/starvation (if no glucosuria)

Transient proteinuriaEnzyme mediated glomerular damage

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PancreatitisCoagulation panel - canineThrombocytopeniaVasculitis (enzyme mediated), DIC

DICPT, PTT, ACT - Elevated

FDP, d-Dimers – highAT3 - low

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PancreatitisElectrolyte panel/blood gases (venous is fine)HCO3,TC0

2, pH, pC02Low - Metabolic acidosis

What clue will your patient give you to check venous blood gases?PantingPotassium

Low – why?H

+ outside the cell exchanged for K+ inside the cellK

+

lost in the urine

Especially a problem with diabetics – why?

Insulin is required to get potassium into the cell where it is needed and stored

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Pancreatitis Treatment: Dogs and Cats“Flop”

Chief Complaint – Not doing well since treating abscess on a toe 1 week ago, vomiting blood 3 days ago regular vet did a UA and blood glucose

UA showed ketones++ and glucose +++, blood glucose 296Has been treating with IV fluids since, getting worse

Did not start insulin because cat not eatingExam - Dehydrated, lethargic, icteric, RR 56vomited coffee grounds and collapsed on abdominal palpation, HR 65/bpm

Responded to atropine IV and fluid bolus

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Pancreatitis Treatment: Dogs and Cats“Flop” - diagnostics

CBC – granulocytes 16,000Profile – glucose 200, BUN 41

TG 500, Chol 297Bili 4.2, ALT 148, ALP normal

Ca 7.0, Phos 1.6UA – SG 1.027, ketones ++, glucose +++, inactive sedimentElectrolytes –

K+ <2.0, Na+ 133, iCa++

1.08

pH 7.032, BE -24, HCO

3

7, TCO

2

8

pCO

2

26.5,

No chest rads or abdominal US done

Urine culture pending

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Pancreatitis Treatment: Dogs and Cats“Flop” - treatment

IV fluids – of course – 45 ml/lb/dayRehydrates and corrects acidosis – which fluids?

Buffered – LRS, Ringers, Normosol, Plasmalyte, etc.Potassium chloride – no – need phosphorus

Potassium phosphates – 100 mEq/L @ max safe rateInsulin – wait 2 hours

Advantage – corrects ketoacidosisDisadvantage – makes hypokalemia and hyposphatemia worseBicarbonate – no

Advantage – corrects acidosis

Disadvantage – will make hypokalemia worse

Cefazolin 100 mg IV TID, famotidine 5 mg IV BID

Cerenia

®

, Pain meds later with insulin

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Pancreatitis Treatment: Dogs and Cats“Flop” – reassess in 4 hours

Glucose - 99 (gave 1 unit NPH SC)PCV – 23%pH 7.228, HC03 10, TCO

2 11pC02 23.9, iCa

++ 1.07, Na+ 130, K+ 2.3

Phosphorus 0.7Red tinged urine, serum ictericHydration normal, general condition slightly improved, no vomiting, not eating

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Pancreatitis Treatment: Dogs and Cats“Flop” – 2 days later

Glucose - 325PCV – 20%pH 7.403, HC03 18.8, TCO

2 20pC02 30iCa

++ 0.92, Na+ 134, K+ 3.7Phosphorus 3.4Urine clear, serum slightly icteric

Hydration normal, general condition greatly improved, eating small amounts, no vomiting

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Protein Losing EnteropathyLow albumin - SI disease and Boxer Colitis

Low albumin and globulin, with anemia - GI bleedingEspecially if BUN increased and creat/phos normal

Panel more often normal with LI diarrhea , except Boxer ColitisHypocholesterolemia - lymphangiectasia

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SepsisCBCNeutrophilia with left shift (<30K/ul)Toxic neutrophils Shifts to neutropenia with timeSerum PanelHypoglycemia – can be severeHypoalbuminemiaHigh bilirubin

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PU-PDSerum PanelLow BUN if PU-PD is severeLow BUN if very low protein dietSodium high normal to high if PU  PDSodium low normal to low if PD  PU

UrinalysisUSG always <1.030 (except PsP)

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Nephrotic SyndromeproteinuriahypoalbuminemiaFluid space shifting – ascites, edema*hint* - foamy urine

Fanconi SyndromeNon-azotemic, but hyperphosphatemicHyperchloremic acidosis

Glucosuria despite normoglycemiaAmino aciduria

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Cholesterol and AlbuminHigh cholesterol plus low albuminThink liver failure or PLN Check blood pressureAbdominal effusion should be a transudateConfirm diagnosis of PLN with UPCCollect daily sample x 3 days

Rule out UTI with UA (inactive sediment) and negative urine cultureConfirm liver disease with bile acids and USLow cholesterol + low albumin

Think liver failure or PLE

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SummaryPowerPoints.pptx

.pdfs – 1 and 6 slides per page

Hidden SlidesPathophysiology Na:K Ratio

References Na:K RatioB12 dose for low B12Instructions and interpretation of SNAP cPL

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SummaryVet HandoutsFluid Analysis Diagnostic Chart

IV Potassium Supplementation Chart

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AcknowledgementsMark C Johnson. Small Animal Clinical Diagnosis by Laboratory Methods, 5th Edition. Ch 12 – Immunologic and Plasma Protein Disorders. Eds. Michael Willard, Harold Tvedten.Jeanne Barsanti.

Small Animal Clinical Diagnosis by Laboratory Methods, 5th Edition. Ch 7 – Urinary Disorders. Eds. Michael Willard, Harold Tvedten.

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AcknowledgementsGreg Lisciandro. www.fastvet.com .