BOF:
16
A 63-year-old male presents
with a history of itching after he has a hot shower. There are no other clinical
features of note. He has no significant past illnesses and is not taking any
medication.
Which of the following investigations is most likely to lead you to a diagnosis?
a) Alkaline phosphatase levels
b) Blood urea and electrolytes
c) Thyroid stimulating hormone levels
d) The fasting blood glucose levels
e) A Full Blood Count
Answer:
e)
Aquagenic pruritus is
caused by the slow release of histamine when the skin is exposed to water.
The slow rate of release of histamine gives a sufficient concentration to cause
itch but is insufficient to cause visible vascular changes.
Aquagenic pruritus is a feature of Polycythaemia Rubra Vera but may also occur
in conditions such as Hodgkin's disease and myeloid metaplasia.
Out of the choices given, the full blood count will pick up this haematological
condition, which is the most likely cause of this type of pruritus in a male in
this age group.
Remember that aquagenic pruritus may precede the development of Polycythaemia
Rubra Vera by several years.
Revision Tip
Revise PRV and Secondary
Polycythaemia KEYS to SUCCESS in Medicine
page 386-388
