Looking at Labs Monocyte count Background Possible causes of • hairy cell leukemia Monocytes are agranulocytes, the monocytosis • overwhelming infection that largest cells of normal blood, and (increased monocyte count) also causes neutropenia the body’s second line of defense >500 cells/mm3 or >0.5 × 109/L • HIV infection against infection. Histiocytes, or >10% • aplastic anemia. which are large macrophagic The most common causes are: phagocytes, are classified as • bacterial infections Interfering factors monocytes in a differential • tuberculosis False-positive values may be leukocyte count. Histiocytes • infective endocarditis caused by: and monocytes are capable of • syphilis. • alprazolam reversible transformation from Other causes include: • ampicillin one to the other. • monocytic leukemia and myelo- • carbenicillin These phagocytic cells of proliferative disorders • chlorpromazine varying size and mobility • gastric, ovarian, or breast cancer • granulocyte-colony stimulating remove injured and dead cells, • Hodgkin disease and other lym- factor (G-CSF) microorganisms, and insoluble phomas • griseofulvin particles from the circulating • recovery state of neutropenia • haloperidol blood. Monocytes escaping from (favorable sign) • lomefloxacin the upper and lower respiratory • lipid storage diseases (Gaucher • methsuximide tracts and the gastrointestinal and disease) • paroxetine genitourinary organs perform a • some parasitic, mycotic, and • penicillamine scavenger function, clearing the rickettsial diseases • piperacillin body of debris. These phagocytic • surgical trauma • prednisone cells produce the antiviral agent • ulcerative colitis, enteritis, and • propylthiouracil called interferon. This test counts celiac disease • quazepam. monocytes, which circulate in • collagen diseases and sarcoidosis False-negative values may be certain specific disorders such as • tetrachloroethane poisoning. caused by: tuberculosis, infective endocar- Phagocytic monocytes (macro- • alprazolam ditis, and the recovery phase of phages) may be found in small • G-CSF acute infections. numbers in the blood in many • glucocorticoids (transient) disorders, including: • triazolam. ■ Normal reference values in • sepsis adults • systemic lupus erythematosus • Absolute monocyte count: • hemolytic anemias. 100 to 500/mm3 or 0.1 to 0.5 × Source: Fischbach FT, Fischbach MA. A Manual of 9 Laboratory and Diagnostic Tests. 10th ed. Philadelphia, 10 /L Possible causes of PA: Wolters Kluwer; 2018. • Differential: 3% to 7% of total monocytopenia white blood cell (WBC) count, (decreased monocyte count) or 0.03 to 0.07 of total WBC <100 cells/mm3 or <0.1 × 109/L count. • prednisone therapy DOI-10.1097/01.CCN.0000578840.90399.28 www.nursingcriticalcare.com September l Nursing2019CriticalCare l 45 Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved..