An HIV positive patient presents to the ED but doesn’t know his CD4 count. He hasn’t been taking his HAART and you’re rightfully concerned that he might be susceptible to opportunistic infections. Unfortunately, you can’t find any information about how immunosuppressed he is. Is there a way to estimate his CD4 count?
Luckily, there is! A 2013 study sought to determine if the automated absolute lymphocyte count (ALC) predicts a “low” (<200 × 10(6) cells/μL) CD4 count in patients with known human immunodeficiency virus (HIV+) who are admitted to the hospital from the emergency department (ED). The study found that a CD4 count of <200 × 106cells/μL is very likely if the ED ALC is <950 × 106 cells/μL and less likely if the ALC is >1,700 × 106cells/μL.
Special thanks to Dr. Mark Andreae for serving as the inspiration for this pearl. Here he is with a mic drop.
Napoli AM, Fischer CM, Pines JM, Soe-lin H, Goyal M, Milzman D. Absolute lymphocyte count in the emergency department predicts a low CD4 count in admitted HIV-positive patients. Acad Emerg Med. 2011;18(4):385-9.