Antihypertensives and dehydration
Antihypertensives and dehydration
During a period of dehydration (e.g. diarrhoea and vomiting), antihypertensive medicines can increase the risk of an acute kidney injury by reducing glomerular filtration. It is important to communicate this risk to people taking antihypertensive medicines.
A discussion with a person suffering from a dehydrating illness should help to inform their decision making around managing their hypertension, and antihypertensive medicines. This could include information about why there is a risk to them, treatment of their illness, recognising signs and symptoms of a worsening condition, and when and how to re-start medicines.
Discussion points
Angiotensin converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) dilate the efferent arteriole of the kidney and reduce blood pressure, which leads to a reduced glomerular filtration rate. Diuretics can cause or worsen hypovolaemia, and thereby provoke a reduction in glomerular filtration rate. A reduced glomerular filtration rate can lead to an acute kidney injury
A good oral intake of fluids and solids, if possible, should be maintained during a period of an acute dehydrating illness. This can be supplemented with oral rehydration salts in those who are at increased risk of dehydration, such as the elderly, people who are immunosuppressed or those with co-morbid conditions.
For example, being unable to hold down any fluids or foods, blood in vomit or faeces, or persistent high temperature
ACEI, ARBs and diuretics can be re-started between 24 and 48 hours of eating and drinking normally. Patients should be advised that they do not need to catch up on any missed doses.
You can provide guidance on the temporary cessation of medicines to people at high risk of acute kidney injury.