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Anemia – What do you mean it’s not

IMHA???Jason M. Eberhardt DVM, MS, DACVIM

Overview

One of the most common CBC abnormalities 10-30% of patients Why is it still so confusing?

Back to basics Systematic approach to anemia

Avoiding common pitfalls

Some thoughts…

“You need to have the correct diagnosis before you can recommend the correct treatment.”

“If you always have the correct diagnosis then you’re not a really veterinarian…you’re probably a breeder.”

“You need to run a minimum of 5 diagnostic tests prior to starting steroids…”

Definitions

Mean Corpuscular Volume (MCV) – Avg. RBC size Macrocytosis Microcytosis Normocytic

Mean corpuscular Hgb concentration (MCHC) – [ ] of Hgb vol. RBC Hypochromic Normochromic Macrochromic

Reticulocytes – Immature RBCs released from B.M. early Normoblasts/metarubricytes – nucleated erythrocytes

Definitions continued…

Poikilocytosis – Variation of RBC shape Rouleaux – Stacks of coins

Small amount is normal Increased fibrinogen or acute phase proteins

Typically seen in inflammatory conditions

Autoagglutination – Aggregate in grapelike clusters Must be differentiated from rouleaux Rouleaux disperses when blood is mixed with saline

Rouleaux or Autoagglutination

Rouleaux Autoagglutination

Before I go any further…

Where do I start……. Back to basics!!!

The first step…

Remember the Total Protein!!! It’s the other half of “blood” It’s cheap! It’s fast

DO NOT OVERLOOK! Are just the RBCs being affected or the plasma as

well?

The next steps…

Morphologic classification RBC indices

Bone marrow response Regenerative vs. Non-regenerative

Description of poikilocytosis? Macrocytic, hypochromic, regenerative anemia

with marked spherocytosis

Morphological classification

Usage of RBC indices (MCV/MCHC) to “describe” the RBCs.

Remember MCV/MCHC are MEAN calculations Large # of RBCs affected prior to increases/decreases Allows characterization of anemia into a category Helps with ranking differential diagnoses

Are found on nearly all in-house CBC units

Normocytic normochromic

Most common “Normal” RBCs Most commonly denotes a non-regenerative

anemia Usually lacks RBC morphology changes

“Pre-regenerative” First 1-3 days of acute loss/lysis

Macrocytic hypochromic

Usually indicates a regenerative anemia Reticulocytes are relatively larger then mature RBCs Hypochromic because Hgb synthesis is not complete

Only 8% of 6752 patients with reg. anemia had both increased MCV & decreased MCHC DiNicola et al.

Macrocytic normochromic

Usually misclassification due to insensitivity of MCV/MCHC Autoagglutination?

Feline Leukemia Poodles – Congenital dyserythropoiesis

Not anemic Large problem in humans

B12 &/or folate deficiency Role in veterinary medicine is questionable

Microcytic hypochromic

Consistent with an iron deficiency anemia Inadequate amount of Hgb is produced

Typically seen in chronic conditions GI blood loss Severe parasitism PSS & Hepatic atrophy Myelodysplastic syndromes

Congenital: Akitas, Shiba Inu, Chow breeds Not typically hypochromic

Bone marrow response

Is there a regenerative response? Evaluation of reticulocytosis

No reticulocytosis/polychromasia expected during first 1-3 days (maybe not at all if anemia stays mild) Response peaks 4-5 days (with normal B.M.) Erythrocyte indices start to change 7-14 days

What is consider regenerative???

Normal patient should have <45,000-60,000 absolute retic count Absolute counts

60,000-150,000 Early/mild response 150,000-250,000 Mild-moderate >250,000-500,000 Moderate-Marked

Relative % 1-4 % - Mild 5-20 % - Moderate > 20 % - Marked

Regenerative anemia

Loss vs. Lysis LOOK AT TOTAL PROTEIN!!!!

External blood loss Low to low-normal T.P.

Hemolytic disease High to high-normal T.P.

Acute external blood loss

PCV does not fully reflect severity first 1-3 days Reticulocytosis should start by day 3 Peak reticulocytes day 4-7 PCV increases to low normal w/in 2 wks May take up to 4-5 weeks to return to normal

Mild anemia does not stimulate strong erythropoietin release

Chronic blood loss

Iron deficiency and negative protein balance develops after “several” weeks in adults Occurs more rapidly in young animals (low iron stores)

Initially non/”pre” regenerative Period of regenerative anemia depending on severity Eventually returns to being poorly/non-regenerative Often have thrombocytosis

Remember RBC indices do not change for 7-14 days Getting blood transfusions???

Hemolytic anemia

Hemolysis is a mechanism NOT a “disease” Lots of “non” immune mediated causes

Low serum phosphorus Normal to increased T.P.

Spherocytosis and/or autoagglutination Over interpretation is common Can be seen in diseases that are not “primary”

Positive Coomb’s Test?

Direct Coomb’s Test

Identifies presence antibodies/compliment on RBCs They may/may not actually be directed towards RBCs This may/may not actually cause damage to RBCs

Neither highly specific or sensitive for IMHA Positive in 60-70% of cases Positive results – should have other evidence of IMHA Effect of steroids?

**NOTE** – What is the end point of the test?????

Breaking it down…

Try to subclassify into intravascular vs. extravascular Alters differential diagnosis

Intravascular – Rapid breakdown in vascular system Pink urine, pink serum Hemoglobinuria best indicator Hyperbilirubinemia typically more profound then in extravascular

Extravascular – removal of RBCs by spleen, liver, B.M. More common Often has icterus, splenomegaly, hepatomegaly

Immune mediated

“Immune-mediated” is a mechanism NOT a disease. Can be 2nd to a number of possible causes

Infectious – Babesiosis, Ehrlichiosis, Leishmaniasis, Rickettsioses, Mycoplasma haemofelis, FeLV

Neoplasia Drugs

Can be initially non-regenerative (esp. in cats)

“Penny” 6 year FS Cocker

Presented for severe lethargy, “yellow skin” and “peeing blood”

Severe, macrocytic, normochromic strongly regenerative anemia with mild-moderate spherocytosis Slide agglutination negative High total protein

Abdominal ultrasound WNL Infectious disease titers all negative

The “Penny” dilemma

Needed multiple transfusion in a 5-6 day period Continued to have hemolysis despite aggressive

immunosuppressive therapy Where do we go from here???

“Peeing” blood – hemoglobinuria Intravascular hemolysis

Intravascular hemolysis

Immune mediated Phosphofructokinase deficiency

Eng. Springers, Amer. Cockers Babesia infection Snake envenomation Heavy metal to toxicity

Zinc Copper

“Penny” 6 yr FS Cocker Spaniel

Presented for severe lethargy, yellow skin and “peeing blood”

Severe, macrocytic, normochromic strongly regenerative anemia with mild-moderate spherocytes

Abdominal ultrasound WNL Infectious disease titers all negative

“Sheldon” 9 yr MC Jack Russell

Presented with clinical evidence of anemia Severe leukocytosis (54,000), severe anemia (9%),

high normal platelets, mild-moderate reticulocytosis Total Protein – 4.9 g/dL VF, Ehr. Neg.

IHMA???

Started on prednisone, cyclosporine, doxycycline Needed 2nd transfusion 1 week later

Added azathioprine

PCV still low 2 weeks later Chest rads and abd. u/s WNL Increased prednisone, continued on cyclosporine and azathioprine

3rd transfusion in 4 weeks Added leflunomide Repeat abdominal ultrasound WNL

More anemia!!!

Initial PCV/TP at EAC 12%/4.8

Reference lab work Hypoalbuminemia (2.6 g/dL), globulin WNL (1.7

g/dL), BUN increased (mild), Total bilirubin (mild) Inflammatory leukogram Severe reticulocytosis

What’s going on???

Horrible IMHA??? Another type of hemolytic anemia? GI bleeding (from prednisone?, GI mass?) Diagnostic plan???????????

Explain the decreased total protein

Non-regenerative anemia

Very common!!! Usually normocytic normochromic

Microcytic, hypochromic anemias Usually no poikilocytosis

Huge majority are mild-moderate in severity 2nd to systemic disease

Before going any further…

Is neutropenia and/or thrombocytopenia also present?

What is the duration of clinical signs? How severe are the clinical signs?

I need more RBCs…

Mild-moderate NR anemia Search for an underlying disease first Anemia of chronic/inflammatory disease

Neoplasia, renal disease, hepatic disease, infectious, inflammatory, endocrine

Drugs

Severe non-regenerative anemia

Toxicity Estrogen? Drugs

Renal disease More than just decreased erythropoietin Chronic dz, decr. RBC lifespan, ineffective

production, blood loss

Why can’t it be easy???

Bone marrow exam Took a long time to develop

Can take even longer to resolve Can still be very confusing

and frustrating

Bone Marrow disease

Immune mediated Maturation arrest vs. Pure Red Cell Aplasia

Myelophthisic syndromes - multiple cell lines often affected Aplastic anemia – B.M. replaced by fat

Can be 2nd to chronic ehrlichiosis Myelofibrosis – B.M. replaced by fibrous Myelonecrosis – Drugs, toxins, viral Neoplasia

“Howard” 9 yr MN DSH

Progressive lethargy, wt. loss for several weeks Marked (12%), macrocytic, normochromic anemia

Total protein 6.2 g/dL Absolute reticulocyte count 40,000

Retic. total 2% Corrected 0.65%

FelV/FIV negative Chest radiographs, abdominal ultrasound WNL

Why cats are not small dogs…

50% of cats with immune mediated disease initially had a non-regenerative response Kohn et al. 2006

2/3 were <3 years (range was 1-9 yr) Bone marrow disease – 53% Infectious – 22% Hemolysis – 11% Immune Mediated – 6%

Severity of anemia associated with B.M. disease Korman et al. 2013

Bone marrow or bust

Owner noticed gradual decline More consistent with non-regenerative disease

Transfusion Recheck 2-3 days later vs. bone marrow now

Marked erythroid hypoplasia/aplasia Immune mediated vs. FelV Bone marrow IFA positive for FelV Stutzer et al. 2010

RBC shape descriptions

Many have little/no clinical significance Anisocytosis, elliptocytes, codocytes, leptocytes,

*echinocytes*

Spherocytes – Evidence of hemolysis Acanthocytes - Hemangiosarcoma, hepatic dz Schistocytes - DIC, Fe def, CHF, myelofibrosis,

hemangiosarcoma, other neoplasia

Summary

Anemia is a common abnormality Cause can often be elusive

Vital to approach systematically RBC indices, bone marrow response,

poikilocytosis DON’T FORGET THE TOTAL PROTEIN!!!

QUESTIONS???