Each week we will aim to bring out a concise email that provides 4-5 key pieces of information addressing a specific issue in clinical therapeutics.
This week: Cholestatic Jaundice (Part 1)
Caroline Holdstock, Regional Pharmacist Manager, Ward MM
Pruritis or itch is a common symptom of many illnesses and is characterised by an unpleasant sensation or irritation of the skin. The severity of itching does not correlate with the severity of cholestasis. Often itching can occur in the early stages of disease but conversely, those with mild disease may have severe itching.There are several mechanisms which may account for itching in cholestasis, but all are poorly understood.
- Histamine: Mast cells and basophils release histamine in allergic reactions. Patients with cholestatic pruritis have higher levels of histamine than those without an itch. Bile acids are known to activate mast cells, and their degranulation by bile acids may account for the resultant itch. However, there is no correlation between the level of histamine and the severity of the itch.
- Bile Acids and Salts: the levels of these are raised in patients with cholestasis, and the itch can be relieved by biliary drainage. However, again the levels of bile acids do not correlate with the intensity of the pruritis.
- Endogenous Opioids: these can be involved in the mechanism of pruritis. External administration of an opioid can cause itch and increased levels of endogenous opioids are seen in cholestasis. Once again there is no correlation between the level of opioid and the intensity of the itch.
- Serotonin: in healthy volunteers, the intradermal injection of serotonin causes itch, but the use of the 5-HT3 receptor antagonist ondansetron has no effect in reducing the itch. This may indicate serotonin alters itch perception.
- Lysophosphatidic acid: a phospholipid with a range of cellular functions has increased levels in the plasma of patients with pruritis but not those without any itch.
- Hormones: pruritis in female patients is often worse in pregnancy and in those taking HRT. Resolution is achieved once the pregnancy is over.
Please consider these issues when preparing or interpreting RMMR reports or education sessions. Contributions of content or suggested topics are welcome and should be sent directly to firstname.lastname@example.org.