I had to smile when I read the heading on these pages. This purports to be 'health information as provided by GPs to patients during consultations'.
However, what follows is as detailed an account of macrocytic and megaloblastic anaemia as any patient could wish for.
If a GP were to pass on all this information in the course of a single consultation they would need to offer 45-minute appointments.
These pages are packed with so much information and use so many Greek and Latin terms that your patient may need a degree in zoology to understand much of it.
So why am I recommending it? Because if your patient is capable of understanding this, there is no better place to send them for information.
I comfort myself with the thought that if your patient is at the less well-endowed end of the intellectual spectrum, then they might well have a hard time absorbing much information about macrocytosis, however simply it is explained.
Why go there: all the information your patients could need.
Downside: it is a complex topic to study.
Information from: Patient UK.
An extensive account
If you have the time and the inclination to cover this topic from all angles, or if you are about to sit an examination in which macrocytosis is likely to come up, then this is the website to visit.
It includes a lengthy section on the pathophysiology of macrocytosis as well as comprehensive sections on clinical signs, differential diagnosis, laboratory tests and treatment.
No corpuscle is left unturned, and the list of possible causes is probably longer than your arm.
What is really disappointing, however, is that despite this wealth of information, there is not a single blood film in sight.
Why go there: because you are really keen.
Downside: no illustrations.
Information from: eMedicine.
Vitamin B12 deficiency
When I was training many years ago, vitamin B12 deficiency really meant pernicious anaemia, subacute combined degeneration of the spinal cord (which I learned everything about but have never seen a case of) and not much else, and the Schilling test was about the extent of the investigative armoury.
Things are very different now, as illustrated by this excellent article. There is a beautiful graphic illustration of vitamin B12 absorption and transport, and a comprehensive flow-chart showing how to investigate a suspected B12 deficiency.
It is interesting that acid suppressant drugs, a relatively new innovation, can be a cause of B12 deficiency, and that monthly injections of cyanocobalamin are increasingly being replaced by daily oral therapy.
The site also links to a patient leaflet on vitamin B12 deficiency, which includes simple explanations and answers questions about vitamin B12 treatment.
Why go there: covers the field very well.
Information from: American Academy of Family Physicians.
Website of the week
This article carries the heading 'Outpatient practice management tips', but it is far from being just a bullet point list of key suggestions. The six-page PDF, which includes a page and a half of references, deals with the topic in a clear and interesting way.
Macrocytosis with and without anaemia are explained. There are two tables, one that lists drugs that can cause macrocytosis and one listing other common pathological causes.
There is a section on how to evaluate macrocytosis, which includes descriptions of blood films, bone marrow findings and the various tests and their interpretation.
The final section includes two excellent slides to give you an idea of what actually happens to those red cells in patients with the condition.
Why go there: well-written and helpful.
Information from: Clinical Medicine Research.
Dr Barnard is a former GP in Fareham, Hampshire