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Test ID RETB Reticulocyte Profile, Blood


Specimen Required


Container/Tube: Lavender top (EDTA)

Specimen Volume: 3 mL

Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.


Secondary ID

616856

Useful For

Assessing erythropoietic bone marrow activity in anemia and other hematologic conditions

Assessment of acute iron deficiency

Monitoring early response to iron therapy or erythropoiesis-stimulating agents

Early monitoring of therapy for nutritional anemias (eg, megaloblastic, iron deficiency) where immature reticulocyte fraction precedes reticulocyte count increase by several days

Monitoring therapeutic efficacy of erythropoietin treatment

Monitoring early engraftment after bone marrow transplantation

Method Name

Flow Cytometry

Reporting Name

Reticulocyte Profile, B

Specimen Type

Whole Blood EDTA

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole Blood EDTA Refrigerated (preferred) 48 hours
  Ambient  24 hours

Clinical Information

Reticulocytes are immature erythrocytes (RBC) that have been released into the peripheral blood from the bone marrow after extrusion of their nucleus. The reticulocyte contains residual polyribosomes used in the formation of hemoglobin in the developing erythrocyte.

 

Iron deficiency suppresses hemoglobin synthesis.(1) Iron indices that rely on measurement of mature RBC may not accurately reflect acute iron status due to their long (approximately 120 days) lifespan.

 

Reticulocytes are differentiated from erythroblasts (RBC containing a nucleus made in the bone marrow) after hemoglobin synthesis is complete and enucleation (extrusion of the nucleus). The reticulocyte is released from the bone marrow into peripheral circulation to complete maturation through loss of its reticulum (RNA and protein visible with staining) over the course of 1 to2 days becoming mature RBC. Ultimately, hemoglobin content in reticulocytes is more reflective of real time hemoglobin synthesis, provided there is not an underlying hematopoietic disorder preventing the production of reticulocytes.

 

Reticulocyte Hemoglobin:

Reticulocyte hemoglobin may be particularly useful to evaluate iron deficiency in chronic kidney disease patients on hemodialysis receiving erythropoietin or other erythropoiesis-stimulating agents as they are prone to chronic inflammatory states that complicate traditional iron evaluations. Studies report reticulocyte hemoglobin concentrations below 29 to 32 pg in this population have areas under the receiver-operating curve (ROC area) of 0.74-0.95 for diagnosing iron deficiency compared to low serum ferritin (ROC area range: 0.53 to 0.63) or transferrin saturation (ROC area range: 0.56 to 0.76).(2)

 

Iron deficiency in childhood is common yet critical to recognize early and treat. Guidelines recommend using hemoglobin in combination with either ferritin and C-reactive protein or reticulocyte hemoglobin. The advantage of using reticulocyte hemoglobin is its lower cost and does not require additional blood volume to be collected when combined with complete blood count testing.

 

Reticulocyte hemoglobin is also used to evaluate response to treatment for iron deficiency, which is one of the earliest markers of response to oral iron treatment (48 hour) in children with severe iron deficiency anemia. Measurement within 7 days from the start of oral iron is predictive of reaching reference value of hemoglobin at day 30 (3) and has been used to improve iron sufficiency rates in neonatal ICU populations.(4)

 

Other patient populations that may benefit from reticulocyte hemoglobin measurement include those with anemia of chronic disease, postpartum, and blood donors.(2)

 

Immature Reticulocyte Fraction:

The reticulocyte is released from the bone marrow into peripheral circulation to complete maturation through loss of its reticulum (RNA and protein measured via fluorescence) over the course of 1 to 2 days becoming mature RBC. The immature reticulocyte fraction measures reticulocyte maturity through quantitation of fluorescence intensity. The most intense signal corresponds to the most immature reticulocytes containing the greatest amount of reticulin. When present in highest proportion of total reticulocytes can be the earliest indicator of beginning erythropoiesis.

Reference Values

% RETICULOCYTES

1-3 days: 3.47-5.40%

4 days-4 weeks: 1.06-2.37%

5 weeks-7 weeks: 2.12-3.47%

8 weeks-5 months: 1.55-2.70%

6 months-23 months: 0.99-1.82%

24 months-5 years: 0.82-1.45%

6-11 years: 0.98-1.94%

12-17 years: 0.90-1.49%

Adults: 0.60-2.71%

 

ABSOLUTE RETICULOCYTES

1-3 days: 147.5-216.4 x 10(9)/L

4 days-4 weeks: 51.3-110.4 x 10(9)/L

5 weeks-7 weeks: 51.8-77.9 x 10(9)/L

8 weeks-5 months: 48.2-88.2 x 10(9)/L

6 months-23 months: 43.5-111.1 x 10(9)/L

24 months-5 years: 36.4-68.0 x 10(9)/L

6-11 years: 42.4-70.2 x 10(9)/L

12-17 years: 41.6-65.1 x 10(9)/L

Adults: 30.4-110.9 x 10(9)/L

 

IMMATURE RETICULOCYTE FRACTION (IRF)

1-3 days: 30.5-35.1%

4 days-1 month: 14.5-24.6%

1-2 months: 19.1-28.9%

3-5 months: 13.4-23.3%

6 months-<2 years: 11.4-25.8%

2-<6 years: 8.4-21.7%

6-<12 years: 8.9-24.1%

12-<18 years: 9.0-18.7%

Female-≥ 18 years: 3.0-15.9%

Male- ≥ 18 years: 2.3-13.4%

 

RETICULOCYTE HEMOGLOBIN

Males:

1 day-5 months: 27.6-38.7 pg

6 months-<2 years: 28.7-35.7 pg

2-<6 years: 27.7-37.8 pg

6-<12 years: 32.4-37.6 pg

12-<18 years: 30.0-37.6 pg

Adults: 30.0-37.6 pg

 

Females:

1 day-5 months: 29.2-37.5 pg

6 months-<2 years: 30.1-35.7 pg

2-<6 years: 29.3-37.3 pg

6-<12 years: 30.4-39.7 pg

12-<18 years: 30.0-37.6 pg

Adults: 30.0-37.6 pg

 

RED BLOOD CELL COUNT (RBC)

Males:

0-14 days: 4.10-5.55 x 10(12)/L

15 days-4 weeks: 3.16-4.63 x 10(12)/L

5 weeks-7 weeks: 3.02-4.22 x 10(12)/L

8 weeks-5 months: 3.43-4.80 x 10(12)/L

6 months-23 months: 4.03-5.07 x 10(12)/L

24 months-35 months: 3.89-4.97 x 10(12)/L

3-5 years: 4.00-5.10 x 10(12)/L

6-10 years: 4.10-5.20 x 10(12)/L

11-14 years: 4.20-5.30 x 10(12)/L

15-17 years: 4.30-5.70 x 10(12)/L

Adults: 4.35-5.65 x 10(12)/L

 

Females:

0-14 days: 4.12-5.74 x 10(12)/L

15 days-4 weeks: 3.32-4.80 x 10(12)/L

5 weeks-7 weeks: 2.93-3.87 x 10(12)/L

8 weeks-5 months: 3.45-4.75 x 10(12)/L

6 months-23 months: 3.97-5.01 x 10(12)/L

24 months-35 months: 3.84-4.92 x 10(12)/L

3-5 years: 4.00-5.10 x 10(12)/L

6-10 years: 4.10-5.20 x 10(12)/L

11-14 years: 4.10-5.10 x 10(12)/L

15-17 years: 3.80-5.00 x 10(12)/L

Adults: 3.92-5.13 x 10(12)/L

 

Cautions

Reticulocyte counts must be carefully correlated with other clinical and laboratory findings.

 

Clotted specimens yield unreliable results and are unacceptable for analysis.

 

Reticulocyte hemoglobin concentration is decreased in thalassemia syndromes and other microcytic anemias resulting from congenital hemoglobin diseases.

 

A pronounced decrease in reticulocyte hemoglobin greater than 25 pg has a high degree of accuracy for detecting alpha or beta thalassemia.(6)

 

Reticulocyte hemoglobin values should be interpreted in the context of the patient’s overall erythrocyte physiology, including knowledge of recent blood transfusions, iron therapy, vitamin B12 or folate deficiency, chemotherapy, and the results of hemoglobin analysis.

Day(s) Performed

Monday through Sunday

Report Available

1 to 3 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

85046

NY State Approved

Yes