Microcytic Anemia: Must Know the Norms!
Definition: Low MCV (mean corpuscular volume); low
Hemoglobin
Normal RBC Indices: vary with age:
| |
Hemoglobin |
Normal MCV: |
Normal Hct |
| Birth: |
119 (110-128) |
Cord: 16.8 g/dL (13.7-20.1) |
55 (45-65) |
| 6-24 mos. |
77 (70-85) |
3 mos. 12.0 g/dL (9.5-14.5) |
36 (31-41) |
| 2-6 years |
81 (75-90) |
6 mos-6 yr 12.0 g/dL (10.5-14.0) |
37 (33-42) |
| 6-12 years |
85 (78-95) |
7-12 yr 13.0 g/dL (11.0-16.0) |
38 (34-40) |
Differential Diagnosis of Microcytic Anemia:
- Iron deficiency without anemia: iron deficiency with anemia: often
associated with thrombocytosis (plts > 600,000), elliptocytosis,
hypochromia
- Thalassemia trait or minor: low MCV with targets on smear; no
hypochromia. Elevated Hemoglobin A2 and F levels.
- Lead poisoning: often seen with associated iron deficiency; basophilic
stippling
- Rare things like sideroblastic anemia, inflammatory disease, and
copper deficiency
Tests that will distinguish different types of microcytic anemia:
- RDW: red cell distribution width elevated in iron deficiency or iron
deficiency anemia. Normal values are 13-15.
- FEP: free erythrocyte protoporphyrin test. Elevated in iron
deficiency. Normal: 30-70.
- Serum Fe and TIBC: low serum Fe and high TIBC confirm iron deficiency;
if both serum Fe and TIBC are low, that reflects chronic illness, not iron
deficiency!
- Serum Ferritin: normal: 35 ng/mL; low in iron deficiency.
Distinguishing microcytic anemia: low MCV and low hemoglobin:
| Test |
Iron Deficiency |
Thalassemia Trait |
Inflammatory Dis. |
| Reticulocyte count |
L |
3-5% |
N |
| RDW |
H |
N |
N |
| FEP |
H |
N |
H |
| Serum Iron |
L |
N |
L |
| TIBC |
H |
N |
L |
| Serum ferritin |
L |
N |
N |
|
MCH |
L |
N |
L |
Iron Deficiency: Responses to Iron Treatment:
- 12-24 hours after treatment started: child feels better
- 36-48 hours after treatment started: bone marrow responds
- 48-72 hours after treatment started: reticulocytes start increasing;
peak at 5-7 days after Rx
- 4-30 days after treatment started: hemoglobin increases
- 1-3 months after treatment started: iron stores repleted
Coulter Counter Readouts: Match with Diagnoses
| |
Normals |
Case 1 |
Case 2 |
Case 3 |
Case 4 |
| Hemoglobin |
11-13 |
8 |
10 |
8 |
12 |
| Hematocrit |
33-38 |
30 |
30 |
26 |
36 |
| WBC count |
5000-10000 |
7500 |
7500 |
15000 |
4500 |
| % Granulo |
50-75 |
70 |
70 |
40 |
40 |
| % Lymphs |
25-50 |
30 |
30 |
30 |
60 |
| Platelets |
> 150000 |
500000 |
150000 |
150000 |
35000 |
| MCV |
80-95 |
60 |
60 |
80 |
80 |
| MCH |
23-30 |
19 |
20 |
25 |
25 |
| MCHC |
28-32 |
29 |
32 |
32 |
32 |
| RDW |
13-15 |
28 |
13 |
21 |
13 |
| MPV |
< 10 |
10 |
10 |
10 |
15 |
| Reticulocyte |
0.5-1.5 |
0.3 |
3 |
6 |
0.8 |
| FEP |
< 30 |
85 |
25 |
25 |
25 |
| |
Case 5 |
Case 6 |
Case 7 |
Case 8 |
|
Hemoglobin |
10.5 |
10 |
8 |
10 |
|
Hematocrit |
31 |
30 |
24 |
30 |
|
WBC |
7500 |
5000 |
1000 |
7500 |
|
% Granulo |
60 |
50 |
20 |
60 |
|
% Lymph |
40 |
50 |
80 |
40 |
|
Platelets |
175000 |
175000 |
35000 |
175000 |
|
MCV |
110 |
85 |
80 |
80 |
|
MCH |
40 |
31 |
25 |
25 |
|
MCHC |
32 |
37 |
32 |
32 |
|
RDW |
13 |
19 |
15 |
13 |
|
MPV |
10 |
10 |
10 |
10 |
|
Reticulocyte |
3 |
5 |
0.1 |
0.5 |
|
FEP |
25 |
25 |
25 |
120 |
1. __________________________ A. Macrocytic Anemia
2. __________________________ B. Hemolytic Anemia
3. __________________________ C. Beta Thal Trait
4. __________________________ D. Spherocytosis
5. __________________________ E. Lead Poisoning
6. __________________________ F. Thrombocytopenia - probable ITP
7. __________________________ G. Pancytopenia compatible with Aplastic
Anemia
8. __________________________ H. Iron Deficiency Anemia
| History |
Hgb/Retic |
Indices |
Smear |
WBC/Platelets |
|
1. 8 yo girl < 3rd %ile; has short thumbs; poor school performance |
11.5 R: 0.4% |
MPV 102 |
Tear drop cells |
125K plts |
|
2. 18 mo old with hx of URI 10 days ago |
6.8 R: 0.1% |
MCV 78 |
Nl smear, WBC |
Normal |
|
3. 6 mo old fever |
9.0 R: 1.0% |
MCV 82 |
Rouleaux formation |
WBC 20000 with inc bands |
|
4. Adoptee from China – 2 yo girl: splenomegaly |
6.3 R: 12% |
MCV 55 |
Target, stippling |
Normal |
|
5. 3mo old with fever lethargy, hypotension – Afro-American |
5.8 R: 16% |
MCV 81 |
Spherocytes, bite cells UA: no RBC but + hgb |
Plts 35,000 WBC 23000, 54% bands |
Diagnoses:
Case 1: ________________ a. Anemia of inflammatory disease
Case 2. ________________ b. Hemoglobin EE beta thalassemia
Case 3: ________________ c. Fanconi’s
Case 4: ________________ d. Transient erythroblastopenia of
childhood
Case 5: ________________ e. G6PD deficiency
Updated 9/01
Next Page |