Complete Blood Count (CBC)

The CBC test includes 9 individual tests to help detect anemia, leukemia, bleeding abnormalities, infection, and more.

Tests include Hemoglobin, Hematocrit, Red Blood Cells, MCV, MCH, MCHC, RDW, White Blood Cells and Platelet Count. 

 The CBC test is known to be overused in preventive clinical practice. In theory, CBC can be thought of as a screening test for occult anemia, infection, and thrombocytopenia.

A large prospective studies performed in the early 1990s concluded that these tests rarely identify clinically significant problems when performed routinely in general outpatient populations (Ruttimann 1992).

In the US these tests are ordered for 25 to 37 percent of patients who present for family physician visits (Merenstein 1992).

Moreover, there is little evidence that performing routine CBCs improves clinical outcome (USPTF 2014).

This test would be useful only if they provided additional diagnostic information that would not otherwise be obtained during a history and physical examination.

 

International standards

  • Offshore medical: There are different opinions in regards to using CBC to assess fitness to work in offshore locations;

 

    • According to UK oil, and gas, the CBC test is not a routine test; may be performed at the discretion of the examining doctor.

 (UK Offshore Oil and Gas 2008)

    • The Norwegian authorities has similar opinion, “CBC is not a routine test; may be performed at the discretion of the examining doctor”.
    • (Norwegian Directorate of Health 2012)
    • While BP in the gulf of Mexico consider CBC with differential as part of the routine assessment components,. (GoM BP 2012)

 

·         Firefighters; it is a required test; CBC with differential, RBC indices and morphology, and platelet count (NFPA 2012).

  • Firefighters: CBC blood tests such as FBC si required for HAZMAT exposures (AFAC 2006).

·         Divers, The initial examination should include a full blood count.

(HSE UK, MA1, 2011)

·         Hazardous occupations; the test is routinely required for employment involving exposure to benzene and few other chemicals (Hong Kong 2004).

 

·         OSHA Standard; Hazardous Waste Operations and Emergency Responses (HAZWOPER): CBC is required for HAZMAT team members and emergency response team (OSHA, 2008).

  • Drivers; CBC is not a routine test; may be requested performed at the discretion of the examining doctor.

(UK DVLA 2014)

Recommendation: the test is recommended for medical assessment of fire fighters, divers, offshore and other safety critical positons.

References

  1. Ruttimann S, Clemencon D, Dubach UC, Usefulness of complete blood counts as a case-finding tool in medical outpatients. Ann Intern Med. 1992 Jan 1;116(1):44-50. PubMed PMID: 1727094.
  2. Merenstein D, Daumit GL, Powe NR. Use and costs of nonrecommended tests during routine preventive health exams. Am J Prev Med. 2006 Jun;30(6):521-7. PubMed PMID: 16704947.Kronick, R. (2014).
  3. The Guide to Clinical Preventive Services. USPSTF. Retrieved from http://www.ahrq.gov/professionals/clinicians-providers/guidelines-ecommendations/guide/cpsguide.pdf
  4. Guidelines - health requirements for persons working on installations offshore. Norwegian Directorate of Health 2012.
  5. Medical Aspects of Fitness for Work Offshore ( 2008 The United Kingdom Offshore Oil and Gas)
  6. GoM Medical Aspects of Fitness for Offshore Work Safety Work Practice (BP 2012)
  7. NFPA 1582, Chapter 6 Medical Evaluations of Candidates - 2012
  8. Australasian Fire Authorities Council (AFAC) Medical Guidelines for Firefighters, 2006
  9. HSE UK, The medical examination and assessment of divers (MA1) 2011, http://www.hse.gov.uk/Diving/ma1.pdf