Absolute Lymphocyte Count (ALC)
Calculates absolute lymphocyte count from WBC and differential. Used in lymphopenia assessment, immunodeficiency, post-chemotherapy monitoring, and COVID-19 severity.
Score interpretation
ALC <0.5 × 10⁹/L — severe lymphopenia
→ High risk of opportunistic infection; consider PCP prophylaxis; investigate underlying cause (HIV, immunosuppression, haematological malignancy)
ALC 0.5–1.0 × 10⁹/L — moderate lymphopenia
→ Consider infection risk; review medications (steroids, immunosuppressants); monitor
ALC 1.0–1.5 × 10⁹/L — mild lymphopenia
→ Monitor; may be reactive or treatment-related
Normal lymphocyte count
→ No specific action required
Elevated ALC — consider CLL, viral illness, reactive lymphocytosis
→ Blood film review; consider haematology referral if persistent >5 × 10⁹/L
Interpretation bands for the ALC. Apply clinical judgement and local guidance.
References
- Murdaca G et al. Lymphopenia in COVID-19: a scoping review on pathophysiology and risk factors. Immunology. 2021;163(4):380–392.
Related
Curated clinical cross-links plus same-class fallbacks.
- Tocilizumab (ICU — Cytokine Storm / COVID-19) · IL-6 Receptor Inhibitor
- Belimumab (Cutaneous Lupus) · BLyS/BAFF Inhibitor (Anti-B-Lymphocyte Stimulator)
- Nirmatrelvir / Ritonavir · COVID-19 Antiviral — Protease Inhibitor Combination
- Molnupiravir · COVID-19 Antiviral — RNA Polymerase Mutagenic Agent
- Remdesivir · Antiviral — RNA Polymerase Inhibitor (COVID-19 / Hepatitis)
- COVID-19 vaccine · Vaccine
- Major Haemorrhage / Massive Transfusion · BCSH; RCOA; RCEM; RCS — BCSH Guidelines
- Anaemia Investigation · BSH / NICE
- Splenomegaly Workup · BSH; BMJ Best Practice
- Deep Vein Thrombosis Diagnosis and Treatment · NICE CG144 / NICE NG158
- Sickle Cell Crisis · BSH 2021 / BCSH
- Neutropenic Sepsis · NICE CG151 2012 / ESMO
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.