Lymphopenia

Definition

Lymphocyte count on FBC in an adult patient that is below the lower limit of the normal range.

Lymphopenia is a common finding, especially in elderly patients. It is rarely of clinical significance. No further investigation is advised in an elderly patient with a lymphocyte count > 0.5 x10⁹/l in the absence of any concerning symptoms.

Lymphopenia may reflect a response to stress such as an acute infection, recent surgery or be iatrogenic secondary to medication, especially immunosuppressant drugs such as steroids. Most cases are reversible and do not require specialist evaluation.

Lymphopenia in adults is a common and usually non-specific finding:

It is important to exclude HIV in persistent unexplained lymphopenia.

Who to refer, who not to refer, how to refer

Who to refer:

Lymphocyte count <1 x 10⁹/l in addition to the presence of weight loss, fever or drenching night sweats.
Patients with lymphadenopathy (nodes > 1 cms) and/or splenomegaly.
Symptomatic patients with persistent lymphopenia (<1 x10⁹/L) with other symptoms should be referred to the most appropriate specialty based on clinical and laboratory features.

Who not to refer:

Anyone who does not meet the referral criteria above

How to refer:

SCI Gateway– Department of Haematology at BGH

Primary care management

Primary care investigations

FBC
Blood film
B12 and folate. Treat if deficiency is detected
Immunoglobulins + protein electrophoresis
Offer HIV testing in moderate to severe lymphopenia (lymphocyte count <1 x 10⁹/l, and < 0.5 x 10⁹/l in over 70).

If additional clinical features suggesting a diagnosis of SLE, RA or other connective tissue disorders please perform a Connective Tissue Disease Panel

Resources and links

Caird FL et al, Cancer Research 2009;69:5383-91. The leucocyte count in old age.
Brass D et al, BMJ 2014;348:g1721.

Last reviewed: 06/05/2025

Next review date: 06/05/2027

Author(s): Charlotte Robertson.