Utility of the peripheral smear and laboratory studies in the ...

Utility of the Peripheral 

Smear and Laboratory 

Studies in the Differential 

Diagnosis of Anemia 

Andrea M. Sheehan, MD 

Assistant Professor of 

Hematopathology

Objectives 

 

 

 

 

 

Review fetal and neonatal hematopoiesis 

Review normal values in pediatric hematology 

Special consideration of neonatal smears 

Use of peripheral smear morphology as an 

aid in differential diagnosis of hematologic 

disorders 

A “hands on” approach - case studies of 

anemia

Fetal Hematopoiesis 

Hematopoiesis starts in yolk sac, ends by 2nd month 

Liver is next – peak is 3rd –4th month, then 

tapers off 

 

In term infant, should have only few small foci of 

EMH that shut down after birth; any significant 

degree of EMH is abnormal 

Bone marrow picks up & is a major site by 4th & 

5th months – dominant site by birth 

In preemies, may still have some EMH in liver & 

occasionally spleen, LN, or thymus

Neonatal Erythropoiesis 

Intrauterine environment relatively hypoxic 

 

 

Mom’s blood not quite fresh from the lungs 

Higher oxygen affinity of Hgb F 

Oxygen rich environment after birth shuts down 

EPO production 

 

 

RBC production decreased by factor of 2 to 3 in first 

few days, by 10 in first week 

Nadir of production is 2nd week

Neonatal Erythropoiesis 

 

 

 

Hgb relatively stable 1st week of life, then 

gradually falls – nadir is 6-12 weeks of age 

 

 

“physiologic anemia of the newborn” 

Generally should not fall below 9.5 g/dL 

MCV also falls 

 

Our lower limit is 72 fL 

Reticulocyte count in increased at birth & first 

few days of life, 

 

 

0-2 days 3-7% 

3-4 days 1-3% 

>4 days down to 0.5-1.5%

Neonatal Red Cells 

 

 

 

 

 

 

Different than infant or child red cells 

Hgb A is present, but Hgb F dominates & 

tapers down over first few months of life 

Shortened life span (60-70 days) 

 

Shorter for preemies (35-50 days) 

Membranes have different composition 

 

More rigid & susceptible to mechanical trauma 

Higher MCV 

 

Immature spleen doesn’t remodel RBCs 

Slightly decreased osmotic fragility

Laboratory Evaluation of the 

Neonate: Things to Keep in Mind 

That Affect the CBC 

Treatment of umbilical cord – 

 

 

 

 

timing of clamping 

Placental vessels contain 75-125 mL of blood at birth 

 

Quarter to one third of fetal blood volume 

Transfusion from placenta to baby usually takes place 

at birth within first minute of birth 

At birth umbilical arteries constrict, but vein is still 

open – blood will follow gravity 

Blood can flow from placenta to baby, especially if 

clamping is delayed or baby held below the level of 

placenta 

 

Hgb can differ by one or more grams

Laboratory Evaluation of the 

Neonate: Things to Keep in Mind 

That Affect the CBC 

Gestational age of the infant 

Age in hours after delivery 

Illness in mom or baby 

 

Level of support required 

Site of sampling 

 

 

Capillary versus venous 

 

Capillary usually higher – 

Warmed versus unwarmed extremity 

Timing of sampling 

can be a significant difference

Notes on Pediatric Normal 

Hematology Ranges 

Normal values vary with age 

At birth, Hgb & MCV are high 

Between birth and 3 mo, Hgb & MCV decrease 

3-6 mo., Hgb rises to around 12 g/dL 

Remains stable until around age 6 years, then comes up 

to 12.5 g/dL 

Age 6-12 years, rises to about 13.5 g/dL 

Then moves up to more adult levels, age 12-18 years 

WBC # & differential vary with age 

Platelets relatively stable throughout

Notes on Neonatal WBCs 

 

 

Leukocytosis typical at birth – 

hours 

 

first 12 

Neutrophils, bands, occasional myeloid 

precursors predominate 

 

Greater left shift in preemies 

WBC declines during first week 

 

 

Lowest around 1 month of age 

Increase in lymphocytes 

 

Predominate throughout early childhood

Notes on Neonatal Platelets 

 

 

 

 

 

Counts don’t vary that much 

Range 100 – 

400K for newborn 

Average count at 2 weeks is 300K 

“adult levels” 

by age six months 

Size and shape more variable in 

newborn than older infants & kids

TCH Hgb Normal Range 

Age g/dL 

0 – 30 days 15.0 – 22.0 

1 mo 10.5 – 14.0 

2 – 6 mos 9.5 – 13.5 

7 mos – 2 yrs 10.5 – 14.0 

3 – 6 yrs 11.5 – 14.5 

7 – 12 yrs 11.5 – 15.5 

13 – 18 yrs/Female 12.0 – 16.0 

13 – 18 yrs/Male 13.0 – 16.0 

≥ 19 yrs/Female 12.0 – 16.0 

≥ 19 yrs/Male 13.5 – 17.5 

As low as 

it gets

TCH MCV Normal Range 

Age FL 

0-30 days 86.0 – 115.0 

1 month 72.0 – 88.0 

2-6 mos 72.0 – 82.0 

7 mos – 2 yrs 76.0 – 90.0 

3-6 yrs 76.0 – 90.0 

7-12 yrs 76.0 – 90.0 

13-18 yrs 78.0 – 95.0 

> 19 yrs 78.0 - 100.0 

As low as 

it gets

TCH MCH Normal Range 

Age PG 

0-30 days 33.0-39.0 

1 month 28.0-40.0 

2-6 mos 25.0-35.0 

7 mos 

– 

2 yrs 23.0-31.0 

3-6 yrs 25.0-30.0 

7-12 yrs 26.0-30.0 

13-18 yrs 26.0-32.0 

> 19 yrs 27.0-31.0

TCH WBC Normal 

Range 

Age x103 /μL 

0 -- 30 days 9.1 – 34.0 

1 month 5.0 – 19.5 

2 – 11 mos 6.0 – 17.5 

1 – 6 yrs 5.0 – 14.5 

7 – 12 yrs 5.0 – 14.5 

13 – 18 yrs 4.5 – 13.5 

≥ 19 yrs 4.5 – 11.0

TCH WBC Diff Normal Range 

Age Seg% Band% Lymphs% Monos% EOS% BASO% ANC 

0–30 d 32-67 0-8 25-37 0-9 0-2 0-1 6.0-23.5 

1 m 20-46 0-4.5 28-84 0-7 0-3 0-1 1.0-9.0 

2–11 m 20-48 0-3.8 34-88 0-5 0-3 0-1 1.0-8.5 

1–6 y 37-71 0-1.0 17-67 0-5 0-3 0-1 1.5-8.0 

7–12 y 33-76 0-1.0 15-61 0-5 0-3 0-1 1.5-8.0 

13–18 y 33-76 0.1.0 15-55 0-4 0-3 0-1 1.8-8.0 

≥19 y 33-76 0-0.7 14-54 0-4 0-3 0-1 1.8-7.7

TCH Platelet Normal Range 

Platelet Count 150,000 – 

does NOT vary much with age 

450,000 μL

Anemia Basics 

 

Definition: 

 

 

Anemia is a level of Red cells, Hemoglobin, 

or Hematocrit that is below the lower limit 

of normal for age. 

Anemia is not a disease, it is a sign of 

disease

Anemia Basics 

Mechanisms: 

 

 

 

Increased loss 

(external) - 

hemorrhage 

Increased destruction 

(internal) - hemolysis 

Decreased production 

(trouble in the bone 

marrow) 

Towels 

in the 

sink are 

soaking 

it up 

Drain is 

too fast 

Faucet 

doesn’t 

work

Approach to the Workup of 

Anemia 

 

 

 

 

 

 

 

 

CBC - 

define & characterize anemia 

Look at red cell indices 

Categorize the anemia based on RBC size 

Reticulocyte count - 

marrow response 

An elevated retic in the absence of bleeding 

indicates hemolysis 

Peripheral smear review 

Confirm the CBC findings 

Anisopoikilocytosis; types of “poikilocytes” 

Consider the differential diagnosis 

Plan your laboratory evaluation

The CBC in Classification of 

Anemia 

Parameters that define the anemia: 

 

RBC, Hgb, Hct 

Parameters that classify the type of anemia: 

 

 

 

MCV 

 

 

Low = microcytic 

High = macrocytic 

MCH & MCHC 

 

 

Low = hypochromic 

Normal or high = macrocytic 

RDW = degree of anisocytosis 

(on the smear a normal 

RBC is the size of a small 

mature inactive 

lymphocyte nucleus)

Anemia 

 

Classification: 

 

 

 

Some are 

too small 

Hypochromic, microcytic (small) 

Normochromic, normocytic (medium) 

Macrocytic (large) 

Some are 

“just right” 

Some are too big

Approach to the PBS 

 

 

Start with the CBC – tells you what you 

expect to see 

Have a system for looking at the smear 

 

 

 

Andrea’s system: RBC then platelets then 

WBC 

Make sure you look at everything and don’t 

miss anything 

Don’t get dazzled by reactive lymphs and 

miss all the schistocytes!

Approach to the PBS 

Slide should be well prepared and well stained 

Go to the feathered edge – 

 

 

 

the “Goldilocks” 

Red cells aren’t too thin (all look like spherocytes) 

Red cells aren’t too thick (all look like agglutination & 

Red cells are just right – 

approach 

well spaced, good central pallor 

Note: it is hard to find the “sweet spot” 

smears due to high Hct 

in newborn 

rouleaux) 

Too thin Too thick Just right

Utility of the PBS Review 

 

Anemic patients – help categorize the anemia 

& aid in differential diagnosis 

 

 

 

 

 

 

 

Along with CBC & RBC parameters 

hypo/micro – 

iron deficiency vs 

Schistocytes/spherocytes – 

Sickle cells/target cells – 

Howell-Jolly bodies – 

Organisms – 

A normal RBC is about the size of a 

mature, inactive lymphocyte nucleus 

malaria 

others 

hemolysis 

hemoglobinopathies 

spleen status 

Look for other abnormal forms

Utility of the PBS Review 

 

Platelets – distinguish true 

thrombocytopenia from 

pseudothrombocytopenia 

 

 

 

 

Look for clumping or satellitism 

Giant platelets are counted as RBC by 

hematology analyzers 

Platelet size – young platelets are larger 

Can look for abnormal platelets (rare)

Utility of the PBS 

Review 

 

WBC 

 

 

Confirm the automated diff or do a manual 

diff 

Morphology of the WBC 

 

 

 

Toxic changes in granulocytes, left shift 

Look for reactive or abnormal cells 

Maturing lymphocytes (hematogones) versus 

blasts

Maturing or “Kiddie” 

Lymphs 

Infants, young children may have some 

circulating immature lymphocytes 

 

Hematogones or “baby B cells” 

If you’re in the single digits (years), you can 

have kiddie lymphs 

The older you are, the fewer we should see in the 

peripheral blood 

The younger you are, the scarier they look (beware 

preemie blood) 

The clinical picture, CBC, and spectrum of 

morphology should help 

Keep in mind “the company they keep”

Immature Lymphoid Cells

Maturing Lymphocytes

Mature Lymphocytes

Blasts vs 

 

 

 

 

“Kiddie” 

lymphs 

This can be hard 

Blasts have higher N/C ratios & very fine, powdery, 

dispersed chromatin +/nucleoli 

“little balls of nucleus” 

Clinical context is helpful – 

begin with? 

Look at the forest 

 

 

 

how suspicious are you to 

Monotony – déjà vu - all the same pine tree 

Heterogeneity – mix of pine, fir, spruce (all evergreens, but 

they all look a bit different) 

Gresik’s rule – look at the company they keep! 

“Private school” vs “public school”

Look at the Forest for the 

Trees 

Are they all 

evergreens? 

Are they all 

the same 

pine tree?

“Public School” 

Maturing Lymphocytes

“Private School” 

Lymphoblasts

ALL vs 

Lymphoblast 

Lymphoblasts 

Lymphocyte 

Normal Lymphocyte

Special Considerations for the 

Peripheral Smears of 

Neonates

Morphologic Findings on 

Peripheral Smear 

 

 

 

 

 

RBC morphology often difficult to appreciate 

 

Hct 

is so high 

Polychromasia 

 

Lots of reticulocytes 

Macrocytes – naturally higher MCV 

Poikilocytosis – funny shapes 

 

Immaturity of spleen – 

not remodeling cells 

Howell-Jolly bodies may be seen in first few 

days before spleen fully matures



 

 

 

Nucleated RBC’s 

 

& immature granulocytes 

Usually not a lot, but may see more if preemie, or 

ill infant 

NRBC’s common 1st day 3-5 

 

 

day of life, disappear by 

In preemies may persist longer than a week 

May appear mildly megaloblastic, may have some 

mildly irregular nuclear contours 

If persist longer, than suggests hemolysis, 

hypoxic stress, or acute infection



Relative predominance of granulocytes at birth 

 

 

Leukocytosis peaks in first 12 hours – mostly 

granulocytes & some bands 

Comes back down by 48 hours after birth 

Preemies may have more left shift, may last 

longer 

Gradual switch to lymphocyte predominance 

 

Usually spectrum of maturing lymphocytes 

(hematogones)



 

 

Platelets may be bigger and a little 

funny looking 

May occasionally see megakaryocyte 

nuclei, especially in preemies

Hard to find a good part of the smear to look at – high Hct

Occasional nucleated red cells, target cells, anisocytosis

Acanthocytes – immature liver & spleen

Acanthocytes, target cells, immature lymphocytes

A rare blast – 

left shift & immature myeloids are okay if 

only few

Howell Jolly body – normal in first week or so of life

Platelets are variable in size with some large forms

Polychromasia – retic is higher in first few days of life

On to the Cases!

Case #1 

15 month old girl

CBC 

RBC = 2.1 x 106 /ul 

Hgb = 6.3 g/dL 

Hct = 18.9% 

MCV = 66 fl 

MCH = 19 pg 

MCHC = 23 g/dl 

RDW = 22.9% 

Platelets = 600 K/ul 

WBC = 5.7 K/ul 

 

Neutrophils 37%, Lymphs 58%, 

Monocytes 3%, Eosinophils 1%, 

Basophils 1% 

Reference Range 

(3.7-5.3) 

(10.5-14) 

(33-39) 

(76-90) 

(23-31) 

(30-34) 

(11.5-16) 

(150-450) 

(5-14.5) 

Neut (37-71), Lymph (17- 

67), Monos (0-5), Eos (0-3), 

Basos (0-1)

Hypochromic Microcytic Anemia: 

Differential Diagnosis? 

 

 

 

 

 

Iron deficiency 

Thalassemia 

Anemia of chronic disease 

Sideroblastic anemia 

Lead poisoning

Most likely diagnosis? 

What do you want to do next?

Iron Studies 

Serum iron = 5 ug/dl 

Serum transferrin = 316 mg/dl 

Transferrin saturation = 1% 

Serum ferritin =

Final Diagnosis? 

Iron Deficiency Anemia

A word about Fe deficiency 

 

 

 

 

Most common cause of anemia worldwide 

Etiology varies with age 

In general, inadequate intake for 

 

 

 

 

Metabolic demands 

Poor absorption 

Bleeding 

Rarely other transport/utilization defects 

Very common in toddlers – high growth 

demands at that age with inadequate intake

Iron Deficiency - 

 

 

CBC 

 

 

 

 

Low MCV (microcytic) 

Labs 

Low MCH & MCHC (hypochromic) 

High RDW 

Increased platelets 

Peripheral smear 

 

Lots of anisopoikilocytosis, elliptocytes (“pencil 

cells”), generally no basophilic stippling & only few 

if any targets

Case #2 

3 year old boy

CBC 

RBC = 3.6 x 106 /ul 

Hgb = 10.3 g/dL 

Hct = 31.0% 

MCV = 63 fl 

MCH = 20 pg 

MCHC = 22 g/dl 

RDW = 14.5% 

Platelets = 349 K/ul 

WBC = 8.4 K/ul 

 

Neutrophils 43%, Lymphs 51%, 

Monocytes 4%, Eosinophils 1%, 

Basophils 1% 


(3.9-5.3) 

(11.5-14.5) 

(34-40) 

(76-90) 

(25-30) 

(32-36) 

(11.5-15) 

(150-450) 

(5-14.5) 

Neut (37-71), Lymph (17- 

67), Monos (0-5), Eos (0-3), 

Basos (0-1)

What do we see? 

Microcytic hypochromic red 

cells

Hypochromic Microcytic Anemia: 


 

 

 

 

 


Thalassemia 

Anemia of chronic disease 


Lead poisoning

Iron Studies 

Serum iron = 30 ug/dl 

Serum transferrin = 160 mg/dl 

Transferrin saturation = 18% 

Serum ferritin = 235 ng/ml 


(55-150) 

(169-300) 

(15-39) 

(20-236)

Hemoglobin Fractionation 

 

 

 

 

 

 

Hgb F = 0.5 

Hgb A = 93.6 

Hgb A2 = 5.9 

Hgb S = 0 

Hgb C = 0 

Hgb other = 0

Final Diagnosis 

Beta thalassemia trait

Thalassemias 

Common in Asian, Mediterranean, black 

populations 

Decreased synthesis of alpha or beta globin 

chains 

 

 

 

Structurally normal, just less of it 

Alpha – usually deletion of one or more genes 

Beta – usually mutation interferes with RNA synthesis, 

processing, or stability 

Severity depends on number abnormal genes 

inherited 

May be combined with other hemoglobinopathies

Diagnosis of Thalassemia 

Beta 

 

 

 

Elevated Hgb A2 by hemoglobin fractionation (3.5- 

8%) 

Hgb A variably decreased 

Hgb F normal or elevated 

Alpha 

 

 

 

For trait – 

no abnormality by hemoglobin fractionation 

Definite diagnosis requires DNA analysis 

Hgb H, Hgb Bart’s with 3 or 4 deletions

Peripheral Smear Findings 

 

 

 

 

Microcytic hypochromic red cells 

Classically less anisopoikilocytosis than 

iron deficiency for thal minor (low RDW) 

 

 

But can be variable 

Abnormalities more severe with 

thalassemia major 

Target cells, fine basophilic stippling 

Elliptocytes usually not prominent

CBC Differences from Iron 

Deficiency 

 

 

 

Classically normal RDW 

 

But not always 

No elevation platelet count 

Microcytosis & hypochromia may be 

more pronounced in thalassemia 

 

Not always

Case #3 

Neonate with anemia


 

 

 

Extreme hypochromia & microcytosis 

Increased nucleated red blood cells 

Target cells, acanthocytes, lots of 

anisopoikilocytosis

Differential Diagnosis 

 

Thalassemia intermedia 

 

 

Alpha 

Beta 

or major


 

 

 

 

 

 

Hgb F = 0 

Hgb A = 0 

Hgb A2 = 0 

Hgb S = 0 

Hgb C = 0 

Hgb other = 100% Hgb Bart’s & Hgb H

Case #3 - 

Diagnosis 

Severe thalassemia - 

chain deletion – 

& hydrops 

4 alpha 

fetal anemia

Alpha Thalassemia 

 

 

 

 

 

 

4 alpha genes 

Thalassemia results from deletion of one or 

more genes 

Loss of 1 or 2 – alpha thal trait 

Loss of 3 – Hgb H disease 

Loss of 4 – fetal hydrops 

Parental studies may be useful 

 

In this case, both parents have 2 gene deletions in 

cis

What if the Hemoglobin 

Fractionation Looked Like This? 

 

 

 

 

 

 

Hgb F = 100% 

Hgb A = 0 

Hgb A2 = 0 

Hgb S = 0 

Hgb C = 0 

Hgb other = 0 

Beta zero 

thalassemia major 

A2 is low at birth and doesn’t come up to 

normal levels until several months old

Case #4 

6 year old girl with fatigue, 

pallor

Initial Labs 

 

 

CBC 

 

 

 

 

 

 

WBC = 12 K/ul 


Hct 

= 24% 

MCV = 115 fL 

MCHC = 38 g/dL 

Platelet = 420 

Reticulocyte count 

 

6%


Spherocytes


 

 

 

 

 

Immune hemolytic anemia 

Hereditary spherocytosis 

Recent blood transfusion 

(Thermal injury) 

(Microangiopathic hemolytic anemias)

Additional Labs 

 

 

 

LDH = 926 U/L 

Indirect bilirubin = 2.3 mg/dL 

Haptoglobin = 5 mg/dL

What’s Next? 

Direct antiglobulin test 

Get more history

Results 

 

 

 

Direct antiglobulin test – 

Family history 

 

 

Anemia runs in the family 

Mom had a splenectomy 

Osmotic fragility - 

positive 

negative

Final Diagnosis? 

Hereditary Spherocytosis

Hereditary Spherocytosis 

Incidence 1 in 5000 in Northern Europeans 

 

Occurs all over the world 

Autosomal dominant inheritance in 2/3 

 

Others de novo mutation or AR 

Membrane skeletal protein defect 

 

 

Spectrin, ankyrin, protein 4.2, and band 3 

 

 

Ankyrin mutations most common (60%) 

Lead to decreased amount of spectrin as well as ankyrin 

Severity of disease correlates with severity of the 

defect


 

 

 

Since membrane isn’t anchored well, small 

vesicles of lipid bilayer can break off, leaving 

the smaller spherocyte 

 

Vesicles are devoid of hemoglobin, skeletal 

proteins 

Same amount of cellular contents in smaller 

amount of membrane 

If enough spherocytes are present, MCHC 

goes up (>36)


Presents in infancy or childhood usually, but can 

be any age 

Hemolytic anemia of variable severity 

 

 

20-30% have compensated hemolysis 

60% with significant spherocytosis and anemia 

Splenomegaly 

Gallstones 

Jaundice 

Respond well to splenectomy

Diagnosis 

 

 

 

 

 

Chronic hemolytic anemia 

Spherocytes on peripheral smear 

Family history 

Negative DAT 

Positive osmotic fragility 

 

 

Not specific for HS, only for spherocytes 

Decreased membrane makes cells less 

tolerant of swelling in hypotonic solution

Case #5 

16 year old boy

Diagnosis? 

Hereditary Elliptocytosis

Hereditary Elliptocytosis 

Seen in all populations 

Incidence 1 in 2000 – 1 in 4000 in US 

Heterogeneous group of disorders 

 

Defects in cytoskeletal proteins 

Red cells fail to regain normal biconcave shape 

after passing through the microcirculation 

Usually mild disorder without clinically significant 

hemolysis, but varies 

 

 

10% may have hemolytic anemia 

If no anemia in the first few years, then it won’t 

develop later in life

Case #6 

4 month old girl

Diagnosis? 

Hereditary 

Pyropoikilocytosis

Hereditary Pyropoikilocytosis 

Related to hereditary elliptocytosis 

 

 

Morphology and clinically similar to more severe HE 

Severe spectrin deficiency 

Presents in infancy or early childhood 

Severe hemolytic anemia – transfusion 

dependent 

Neonatal jaundice – first few weeks of life 

Morphology 

Red cell budding, fragments, triangulocytes, bizarre 

shapes, some elliptocytes, spherocytes 

Similar picture as severe burns

Hereditary Pyropoikilocytosis 

 

 

 

 

 

Markedly abnormal osmotic fragility 

Increased autohemolysis 

CBC - marked microcytosis (all those 

fragments) 

Thermal sensitivity 

 

Cells fragment at 45 to 46 o C (normal 49 o C) after 

10-15 minutes of heating 

Hemolytic anemia improved with splenectomy 

 

Hgb 10-14 g/dL 

with 3-10% reticulocytes

Case #7


Spherocytes again 

LOTS of polychromasia

In this case, the DAT was 

positive 

Diagnosis: Warm autoimmune 

hemolytic anemia

Spherocytes on the Smear 

 

 

 

 

 

 

Spherocytes suggest extravascular hemolysis, 

but smear alone can’t tell you why 

AIHA and HS look comparable on PBS 

Clinical history may be helpful – chronic 

versus acute 

DAT is helpful – establish immune nature 

Osmotic fragility isn’t really helpful 

 

Positive if a lot of spherocytes around, but doesn’t 

tell you why they are there 

MCHC can go up if enough spherocytes are 

around, but can’t distinguish the cause

Case #8 

3 year old boy with fever

CBC 

 

 

 

 

 

 


Hct 

= 18.5% 

MCV = 74 fL 

MCH = 27.2 pg 

RDW = 15.2% 

Plt 

= 27 K/ul 

 

WBC = 15.81 K/ul 

 

 

 

 

 

Seg 

Band = 

= 35.4% 

17.6% 

Lymph = 31.9% 

Mono = 9.2% 

Meta = 

5.9%

Diagnosis? 

Low platelets + moderate 

schistocytes = Microangiopathic 

hemolytic anemia (MAHA)

Differential Diagnosis 

 

 

 

 

 

 

TTP 

HUS 

DIC 

(HELLP) 

(Malignant hypertension) 

(Snake bite)

What do you want to do now?

Labs 

 

 

 

 

 

Elevated BUN/Cr 

Elevated LDH, indirect bilirubin 

Absent haptoglobin 

Positive blood on urine dipstick 

Clinical history: patient with abdominal 

pain & bloody diarrhea

Microbiology 

 

Stool cultures positive for E. coli 

0157:H7

Final Diagnosis 

Hemolytic Uremic Syndrome 

associated with E. coli 

0157:H7

Hemolytic Anemia – 

Prodrome of fever, 

diarrhea, abdominal 

pain, vomiting before 

HUS 

Clinical 

Triad of renal failure, 

microangiopathic 

hemolytic anemia, 

thrombocytopenia 

Shiga toxin producing 

E. coli O157:H7 

 

 

 

 

 

 

CBC 

 

D+ HUS 

Normal or high MCV 

High reticulocyte count 

High LDH 

Low haptoglobin 

Increased hemoglobin 

breakdown products 

 

 

Labs 

Increased indirect bilirubin 

Increased urine & fecal 

urobilinogen 

Free plasma & urine 

hemoglobin (+/-)

Hemolytic Anemias – 

 

 

 

 

In General 

Premature removal of circulating RBCs 

Intravascular 

 

Lysis of RBCs 

Extravascular 

 

within the circulatory system 

Removal of RBCs by reticuloendothelial system 

(liver, BM, spleen) 

Bone marrow production increased to 

compensate 

 

Anemia when the BM can’t keep up

Causes of Hemolytic Anemias 

 

 

 

 

Hereditary versus acquired 

 

For acquired: immune vs 

non-immune 

Intrinsic (corpuscular) defects vs 

extrinsic (extracorpuscular) defects 

Intrinsic are usually inherited 

Extrinsic are usually acquired

CBC Findings in Hemolytic 

Anemia 

Anemia – 

 

decreased Hgb & Hct 

Variable in severity depending on etiology 

RBC Indices 

 

 

 

 

 

Depend in part on the etiology 

Usually normochromic normocytic 

Macrocytic if high reticulocyte count 

If MCHC elevated (>36), suggestive of spherocytes 

RDW may be increased if anisopoikilocytosis

Other CBC Clues 

 

With acute hemolytic anemia 

 

 

Increased platelets 

Increased WBC with left shift

Hemolytic Anemia on PBS 

Usually normochromic, normocytic (or 

macrocytic) RBCs 

Polychromasia +/nucleated RBCs 

Schistocytes - suggest intravascular 

 

 

With low platelets – TTP, DIC, HUS 

Artificial heart valves 

Spherocytes - 

 

 

suggest extravascular 

Hereditary, autoimmune, transfusion, maternal-fetal 

ABO incompatibility 

Burns/thermal injury - microspherocytes


Clues 

Elliptocytes, stomatocytes 

Bite or helmet cells 

 

Unstable hemoglobins, oxidant damage 

Sickle cells, target cells – 

hemoglobinopathies 

Target cells, acanthocytes – liver disease 

Post splenectomy type changes (HJB) 

Organisms – malaria

Hemolytic Anemia on PBS 

WBC usually unremarkable 

 

 

May see reactive changes in infections 

May see malignant cells if associated with 

lymphoproliferative disorder 

Keep in mind we may not see much 

but polychromasia 

Lack of spherocytes or schistocytes, 

does NOT exclude hemolysis

Summary of Markers of 

 

 

 

 

 

Hemolysis 

Elevated reticulocyte count 

Elevated LDH 

Decreased haptoglobin 

Elevated hemoglobin breakdown products 

 

 

Increased indirect bilirubin 

Increased urine & fecal urobilinogen 

Free plasma & urine hemoglobin 

 

 

Associated with intravascular hemolysis 

When haptoglobin overwhelmed

Peripheral Smear Clues 

Extravascular hemolysis (AIHA) 

 

Decreased RBCs, spherocytes and polychromasia 

Intravascular hemolysis 

 

 

 

Schistocytes, red cell fragments, polychromasia 

Some spherocytes, too 

If microangiopathic – low platelets 

If intrinsic RBC abnormality enzyme or 

hemoglobin abnormality, may see abnormal RBC 

shapes 

Sickle cells, target cells in sickle cell disease 

Bite cells in G6PD deficiency

Case #9 

2 year old boy with anemia

What do you see? 

Acanthocytes (Spur Cells)

Differential Diagnosis for 

Acanthocytes 

 

 

 

 

 

 

 

 

Post splenectomy 

MAHA 

AIHA 


Thalassemia major 

Neonatal period 

Hypothyroidism 

Vitamin E deficiency

Differential Diagnosis for lots 

of Acanthocytes (>10%)? 

 

 

 

 

 

 

Abetalipoproteinemia (Bassen Kornzweig 

syndrome) 

Homozygous hypobetalipoproteinemia 

Advanced liver disease due to neonatal 

hepatitis, metastatic liver disease, Wilson’s 

disease, cardiac cirrhosis, alcoholism 

Choreoacanthycytosis 

McLeod blood group phenotype 

In(Lu) blood group phenotype 

50-90% of RBCs are acanthocytes

Acanthocytes vs 

“spur cells” 

Multiple irregular unevenly 

distributed thorny 

projections 

No central pallor 

Smaller than normal RBCs 

Due to derangement of 

lipid content of RBC 

membrane 

 

 

 

 

 

 

Echinocytes 

“burr cells” 

Evenly distributed short 

projections 

Central pallor 

Same size or slightly 

smaller than RBCs 

Most commonly 

represents an artifact 

Variety of artifactual or 

physiologic 

environmental changes

Acanthocytes 

Echinocytes 

Color Atlas of Hematology, CAP Press, 1998

Additional History 

 

Patient with severe liver disease but 

etiology not yet determined

Case #10 

14 year old boy with anemia

Labs 

 

 

CBC 

 

 

 

Anemia – 

MCV = 70.6 fL 

MCH = 21.4 pg 

Retic 

 

4% 

Hgb/Hct of 9.3/28

Sickle Cells & Targets – 

Problem 

No 

But microcytic & hypochromic 

as well?


 

 

 

 

 

 

Hgb F = 12.1 

Hgb A = 0 

Hgb A2 = 5.9 

Hgb S = 82 

Hgb C = 0 

Hgb other = 0

Case #10 Diagnosis 

Heterozygous sickle – 

zero thalassemia 

Beta

Sickle Cell Disease 

 

 

Peripheral smear – sickle cells & 

hemoglobin fractionation are diagnostic 

Indices are usually normochromic & 

normocytic 

 

Note: Patient gets macrocytic if taking 

hydroxyurea

Sickle Cell Disease 

 

 

Hypochromia & microcytosis is not typical in 

sickle cell disease 

Possibilities 

 

 

 

Co-inheritance alpha thalassemia (very common) 

Co-inheritance beta thalassemia (not as common, 

but happens) 

 

Has severe sickle cell disease if beta zero (no A at all); 

beta plus (makes some A) may do better 


 

Theoretically possible, especially at very young age, but 

unlikely since they tend to get iron overloaded over time

A Few Words About S Trait & 

Thalassemias 

 

 

If patient has coinheritance of alpha 

thalassemia & S trait, expect approximately 

65/35 ratio of A and S, respectively 

 

S is transcribed less efficiently than Beta, so when 

competing for limited alpha chain, less S than 

would expect without thalassemia (not quite 

50/50 split) 

Beta thalassemia – 

much A is made 

 

severity depends on how 

Elevated A2 is helpful for making the diagnosis, 

along with hypo/micro RBC indices

Any questions, y’all? 

Adapted from Andreas Vesalius, De Humani 

Corporis Fabrica, 1543, plate 22

Utility of the peripheral smear and laboratory studies in the ...

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