Lab Test

Cytomegalovirus IgM


Test Codes



Special Chemistry


This test is not FDA approved for testing blood or plasma donors.

Specimen Collection Criteria

Collect: One Gold-top SST tube. (Minimum Whole Blood: 2.0 mL)

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged collection tube within two hours of collection. (Minimum Serum: 0.5 mL)

Preparation for Courier Transport

Transport: Centrifuged collection tube, refrigerated (2-8°C or 36-46°F). (Minimum Serum: 0.5 mL)

Rejection Criteria

Plasma specimens. 

Severely lipemic, icteric, or grossly hemolyzed specimens.    


In-Lab Processing

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Room temperature is acceptable for a maximum of two hours. (Minimum Serum: 0.5 mL)


Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers® with Separator Gel
Room Temperature (20-26°C or 68-78.8°F): 8 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers® without Separator Gel
Room Temperature (20-25°C or 68-77°F): 8 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 8 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 1 year

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days


Royal Oak Special Testing Laboratory


Tuesday – Saturday.
Results available within 2 business days.

Reference Range

Negative: Less than or equal to 29 AU/mL.
Equivocal: 30-34.9 AU/mL.
Positive: Greater than or equal to 35 AU/mL.

Test Methodology

Chemiluminescent Immunoassay.


  • CMV IgM antibodies usually appear 3-4 days after the onset of symptoms. While the presence of IgM antibodies suggests current or recent infection, low levels of IgM antibodies can occasionally persist for more than 12 months post-infection. IgM may or may not be present during CMV reactivation (1).
  • CMV IgM testing may not be reliable in immunocompromised patients because these patients may not produce detectable amounts of CMV IgM. The preferred method for CMV diagnosis is CMV culture and/or CMV PCR of buffy coats, bronchoalveolar lavage (BAL) cells, or tissue biopsies.
  • False negative results may occur when serum specimens are drawn very early during the acute stage or late in the convalescent stage of CMV infection.
  • Negative results do not rule out CMV infection.
  • It is not possible to determine the specific time when a primary infection occurred due to the fact that CMV IgM may persist for months after a primary infection.

Clinical Utility

CMV IgM detection can assist in the diagnosis of recent CMV infections and CMV reactivations. In the presence of CMV IgG, CMV IgM tests cannot distinguish primary CMV infections from CMV reactivations.

Clinical Disease

Most adults and children who are infected with CMV are asymptomatic. Symptomatic patients may experience fever, sore throat, fatigue, and lymphadenopathy. CMV can persist in the body in a latent form and reactivate at a later date. CMV infections in pregnant women, newborns and immunocompromised individuals can pose substantial medical risk. In utero infection can cause mental retardation, microencephaly, hearing loss, and developmental delays. Immunocompromised individuals can develop serious CMV infections. Several serious, often life-threatening syndromes have been associated with CMV infection including: heterophile- negative mononucleosis-like syndrome in young adults, cytomegalic inclusion disease in congenitally infected infants, interstitial pneumonia, retinitis, and febrile illness among organ transplant and other immunocompromised patients, and a post- transfusion syndrome characterized by pneumonitits, hepatitis, and atypical lymphocytosis, especially in premature infants (1).


Cytomegalovirus infections are common throughout the world. By puberty, 40-80% of children are infected and by age 35, almost 100% of the population is infected (1).

Incubation Period

3-8 weeks following transfusion and 3-12 weeks following perinatal infection (1).


CMV is transmitted by contact with body fluids, through blood transfusion, or organ transplantation. The most common routes of infection are from close contact with infected oropharyngeal secretions, vaginal or cervical secretions, semen, urine, breast milk or blood. Congenitally or perinatally infected children can shed large amounts of virus in saliva for 2-4 years and for 5 or more years in urine (1).


  1. Wiedbrauk D, Johnston SLG. Manual of Clinical Virology, Raven Press, New York, NY, 1993.

CPT Codes

LOINC: 24119-0


Last Updated


Microtainer® and Vacutainer® are registered trademarks of Becton, Dickinson and Company.
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