Reticulocyte Count (Retic)

CPT: 85045

Expected Turnaround Time

24 Hours

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Specimen Requirements


Whole Blood


EDTA (Lavender Top Tube)

Storage Instructions

Room Temp., Refrigerated (2-8 C)

Stability Requirements

Room temp. 48hrs, Refrigerated 4 days

Test Details

Additional Information

RBCs are produced in the bone marrow, where blood-forming (hematopoietic) stem cells differentiate and develop, eventually forming reticulocytes and finally becoming mature RBCs. Reticulocytes are visually slightly larger than mature RBCs. 

Unlike most other cells in the body, mature RBCs have no nucleus, but reticulocytes still have some remnant genetic material (RNA). As reticulocytes mature, they lose the last residual RNA, and most are fully developed within one day of being released from the bone marrow into the blood. The reticulocyte count is a good indicator of the ability of the bone marrow to adequately produce RBCs (erythropoiesis). 

RBCs typically survive for about 120 days in circulation, and the bone marrow continually produces new RBCs to replace those that age and degrade or are lost through bleeding. Normally, a stable number of RBCs is maintained in the blood through continual replacement of degraded or lost RBCs. 

A variety of diseases and conditions can affect the production of new RBCs and/or their survival, in addition to those conditions that may result in significant bleeding. These conditions may lead to a rise or drop in the number of RBCs and may affect the reticulocyte count. 

Reticulocytes are red blood cells that are still developing. They are also known as immature red blood cells. Reticulocytes are made in the bone marrow and sent into the blood. About two days after they form, they develop into mature red blood cells. These red blood cells move oxygen from the lungs to every cell in the body. 

A reticulocyte count is used to determine the number and/or percentage of reticulocytes in the blood to help evaluate conditions that affect RBCs, such as anemia or bone marrow disorders. Reticulocytes are newly produced, relatively immature RBCs. They form and mature in the bone marrow before being released into the blood. 

The reticulocyte count may be used:

  • As a follow-up to abnormal results on a complete blood count (CBC), RBC count, hemoglobin, or hematocrit, to help determine the cause 
  • To determine if the bone marrow is functioning properly and responding adequately to the body’s need for RBCs 
  • To help detect and distinguish between different types of anemia 
  • To monitor response to treatment, such as that for iron-deficiency anemia 
  • To monitor bone marrow function following treatments such as chemotherapy 
  • To monitor bone marrow function following a bone marrow transplant 

Most often, a reticulocyte count is performed with an automated instrument (hematology analyzer) and can be done simultaneously with a CBC, which includes an RBC count, hemoglobin, and hematocrit. Either an absolute number of reticulocytes and/or a percentage of reticulocytes of total RBC count can be reported, although the absolute number is more commonly reported. 


  1. Chernecky CC, Berger BJ. Reticulocyte count-blood. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. Philadelphia, PA: Elsevier; 2013:980-981. 
  2. Culligan D, Watson HG. Blood and bone marrow. In: Cross SS, ed. Underwood’s Pathology. 7th ed. Philadelphia, PA: Elsevier; 2019:chap 23. 
  3. Lin JC. Approach to anemia in the adult and child. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 34. 

Statement on Medical Necessity
All ordered tests should be medically necessary for the diagnosis or detection of disease, illness, impairment, symptom, syndrome, or disorder and the results should be used in the medical management and treatment decisions for the patient. Solaris requires ICD-10 codes with each order for lab testing and both the tests ordered and the diagnosis should be documented in the provider’s medical record for the patient. The United States Department of Health and Human Services, Office of Inspector General, takes the position that a provider who orders medically unnecessary tests may be subject to civil penalties.

Panels and Profiles
Solaris offers Providers the convenience of ordering test combinations in a group at times with the flexibility to choose appropriate test(s) for individual patients. Providers should only order those tests that he or she believes are medically necessary for each patient, and a lesser inclusive profile or individual tests should be ordered if not all tests in the test combination/profile are medically necessary. All tests offered in a test combination/profile may be ordered separately as individual tests. Solaris encourages clients to contact their Solaris representative if the testing configurations shown do not meet individual needs for any reason, or if some other combination of procedures is needed.

CPT Codes
CPT Codes listed are in accordance with Current Procedural Terminology, a publication of the American Medical Association. CPT codes are the responsibility of the billing party and are listed here for informational purposes. Correct coding may vary from one carrier to another. Solaris may bill specific carriers using codes other than what is shown.


For questions or inquiries related to testing please reach out to or contact us by phone at (844) 550-0308.