_id

683a1605c782e11e38d1b135

id

2203

title

Absolute Lymphocyte Count (ALC)

full_title

Absolute Lymphocyte Count (ALC)

short_title

Absolute Lymphocyte Count

med_description

Assesses number of lymphocytes and predicts CD4 count.

short_description

ALC count, and predicted CD4 Count.

slug

absolute-lymphocyte-count-alc

description

The Absolute Lymphocyte Count (ALC) assesses number of lymphocytes and predicts CD4 count.

keywords

hiv, aids, alc, lymphocyte, natural killer cells

complaint

[ "Fever" ]

formula

ALC = WBC count x 1000 x % lymphs

evidence

Absolute lymphocyte count is a hematologic principle that has been validated in an emergency setting; an ALC <1,000 cells/mm³ predicted CD4 counts less than 200 cells/mm³ with 67% sensitivity (95% confidence interval 62-72%), specificity of 96% (94-98%), positive predictive value 91% (87-85%), and a negative predictive value of 81% (78-84%). An ALC <2,000 cells/mm³ predicted CD4 counts less than 200 cells/mm³ with sensitivity 97% (95-99%), specificity 41% (37-45%), positive predictive value 52% (48-56%), and negative predictive value 95% (92-98%).

A more recent study that looked into the PPV and NPV of the total lymphocyte in 184 HIV positive patients. Sensitivity, specificity, positive and negative predictive values of lymphocyte count <1,200 cells/mm³ to predict CD4 count <200 cells/mm³ were 72.2%, 100%, 100%, and 95.7% respectively.

measurements

[ { "name": "% Neutrophils", "unit": "neut", "error_min": "-0.01", "error_max": "100.01", "warn_min": "35", "warn_max": "100", "conversion": "1", "normal_max_si": "0", "normal_max_us": "0", "normal_min_si": "0", "normal_min_us": "0", "units_si": "%", "units_us": "%" }, { "name": "White Blood Cell Count", "unit": "wbc", "error_min": "0.0001", "error_max": "500", "warn_min": "1.5", "warn_max": "100", "conversion": "1", "normal_max_si": "10.7", "normal_max_us": "10.7", "normal_min_si": "3.7", "normal_min_us": "3.7", "units_si": "× 10⁹ cells/L", "units_us": "× 10³ cells/µL" } ]

information

Predicted CD4 from ALC (van der Ryst E 1998)

refrences

{ "Clinical Practice Guidelines": [], "Manufacturer Website": [], "Original/Primary Reference": [ { "href": "https://www.ncbi.nlm.nih.gov/pubmed/9737494", "text": "Shapiro NI, Karras DJ, Leech SH, Heilpern KL. Absolute lymphocyte count as a predictor of CD4 count. Ann Emerg Med. 1998 Sep;32(3 Pt 1):323-8." } ], "Other References": [ { "href": "https://www.ncbi.nlm.nih.gov/pubmed/9803965", "text": "van der Ryst E, Kotze M, Joubert G, Steyn M, Pieters H, van der Westhuizen M, van Staden M, Venter C. Correlation among total lymphocyte count, absolute CD4+ count, and CD4+ percentage in a group of HIV-1-infected South African patients. J Acquir Immune Defic Syndr Hum Retrovirol. 1998 Nov 1;19(3):238-44." }, { "href": "https://pubmed.ncbi.nlm.nih.gov/22676809-total-lymphocyte-count-as-a-surrogate-marker-for-cd4-count-in-resource-limited-settings/", "text": "Obirikorang C, Quaye L, Acheampong I. Total lymphocyte count as a surrogate marker for CD4 count in resource-limited settings. BMC Infect Dis. 2012;12:128." } ], "Outcomes": [], "Validation": [ { "href": "", "text": "Ayalew Tefferi ed. Primary Hematology. Totowa, NJ: Humana Press, 2001." } ], "Validations": [] }

pearls

• If the ALC is low, the CD4 will usually be low (Shapiro 1998).

• Currently evidence is mostly around HIV-1 treatment-naive patients.

• Other viral infections such as influenza or EBV can cause lymphopenia.

• Does not aid in the diagnosis of HIV.

usecase

• Frequently used in the ED setting because CD4 tests take longer to come back and need patient consent.

• Used in limited-resource settings where CD4 tests are costly or unavailable.

reasons

Serves as a surrogate for CD4 count in HIV patients who are naive to antiretroviral therapy in resource-limited areas.

next_advice

• In the right clinical context, consider undiagnosed HIV as a cause of low lymphocyte count.

• If available, obtain a CBC with differential and CD4 count for confirmation.

next_actions

Does not change management, but helps support the suspicion of HIV infection with low CD4.

next_management

diseases

[ "Coronavirus", "COVID-19", "HIV/AIDS" ]

input_schema

[ { "conditionality": "", "default": null, "fhir_rules": null, "inct": null, "label_en": "<p>Lymphocytes</p>", "name": "lymph", "optional": false, "tips_en": "", "type": "textbox", "unit": "neut" }, { "conditionality": "", "default": null, "fhir_rules": null, "inct": null, "label_en": "<p>White Blood Cell Count</p>", "name": "wbc", "optional": false, "tips_en": "Per 1000. Enter as 8.4, not 8400", "type": "textbox", "unit": "wbc" } ]

instructions

published

2022-04-21T20:29:10.312Z

purpose

[ "Formula", "Diagnosis" ]

search_terms

[ "alc", "lymph", "cd4", "cd8", "natural killer cells", "immune", "coronavirus", "covid", "covid19", "covid-19", "covid 19" ]

seo

{ "keywords_en": "hiv, aids, alc, lymphocyte, natural killer cells", "meta_description_en": "The Absolute Lymphocyte Count (ALC) assesses number of lymphocytes and predicts CD4 count." }

specialty

[ "Critical Care", "Emergency Medicine", "Family Practice", "Hematology and Oncology", "Infectious Disease", "Internal Medicine", "Palliative Care/Hospice" ]

departments

[ "Immunologic", "Infectious" ]

tags

[]

version_number

1

versions

[]

related

[ { "calcId": 4050, "short_title_en": "DRIP Score", "slug": "drug-resistance-pneumonia-drip-score" }, { "calcId": 2654, "short_title_en": "qSOFA", "slug": "qsofa-quick-sofa-score-sepsis" }, { "calcId": 33, "short_title_en": "PSI/PORT Score", "slug": "psi-port-score-pneumonia-severity-index-cap" } ]

ismed

false

section

[ "whenToUseViewed", "pearlsPitfallsViewed", "whyUseViewed", "nextStepsViewed", "evidenceViewed" ]

cleaned_departments

[ "immunology", "infectious" ]

cleaned_use

[ "Frequently used in the ED setting because CD4 tests take longer to come back and need patient consent.", "Used in limited-resource settings where CD4 tests are costly or unavailable." ]

pub

false