This gives a really nice, simple clear outline on how to investigate patients, as well as a lot of more complex advice aimed at specialists. I have tried to distill the bits that are useful for us. If you need more information see the guideline appendices:
- Table II - a pretty exhaustive list of disorders that can cause eosinophilia.
- Table III - gives a good list of all the infectious diseases that can cause eosinophilia, including countries where they can be caught and useful investigations.
- Table V - a list of further investigations that can be done depending on the likely underlying cause. A lot of these wouldn't be for us to do.
Causes of eosinophilia
This is not an exhaustive list - just the ones we are likely to see a lot. If none of these apply, maybe look at the guideline to see if others may be relevant.
- Allergic disorders (eg asthma, hayfever, urticaria, dermatitis). When the underlying condition is controlled, the eosinophilia normally disappears.
- Drugs (including lots of antibiotics, anticonvulsants and some herbal and dietary supplements)
- Infectious diseases (including many parasitic and fungal disorders - helminth infections are the most common)
- Gastrointestinal disorders (including inflammatory bowel disease, coeliac disease, chronic pancreatitis and primary eosinophilic disorders)
- Rheumatological (SLE and RA - about 3% of RA patients, but normally it is transient).
- Respiratory (allergic aspergillosis, sarcoidosis)
- Neoplasms (including solid tumours - especially in advanced disease, lymphomas, ALL and primary eosinophilic disorders)
- Atherothrombolic disease (only during the acute phase)
- Chronic graft vs host disease
What should you cover in the history?
- Allergic disorders
- Lymphadenopathy (looking for lymphoma)
- Rashes (rare dermatological disorders can cause it)
- Constitutional symptoms (eg drenching night sweats, fever, weight loss, pruritus, alcohol-induced pain - all these are looking for cancers and lymphomas)
- Cardiac or respiratory symptoms (eg damage caused by the eosinophilia)
- GI symptoms (looking for IBD etc)
- Travel history (going back many years - up to 50 may be relevant...)
- Drug history
What basic investigations should we be doing?
- FBC / blood film
- Bone profile
- lactate dehydrogenase (maybe not us... - but looking for lymphoma)
- ESR and / or CRP
Be aware that if you are doing stool samples to look for parasites that it can take several weeks for them to become positive. The eosinophilia is often associated with the parasites moving through the tissues. Once they reach the gut, the eosinophilia often settles.
Serology for parasites can take 4 - 12w to become positive.
Could this be travel related?
If you think this could be travel related, there is a useful document from the Journal of Infection, which gives more information about investigations etc. Most of it is aimed at specialists. There is however a useful list of all the Travel Health clinics with contact details, which may be useful if you need to refer the patient on.
Who needs further investigations?
- 0.5 - 1.5 x 10 to the 9/L - if the patient is well then they may need no further investigations.
- 1.5 x 10 to the 9 / L - needs further investigation
- 0.5 - 1.5 x 10 to the 9/L with systemic symptoms - needs further investigation