Chronic kidney disease

Written by Dr Claudia Pastide, 9th March 2019

Chronic kidney disease (CKD) affects around 3 million people in the UK, although about a third of people are undiagnosed1.

This is because CKD is usually a condition that starts without obvious symptoms and then progresses quietly, until it is picked up by a chance blood test, urine test or the person presents unwell and with typical signs such as swollen feet and ankles.

The common causes of CKD are conditions that many are susceptible to due to our diets and lifestyles, in particular high blood pressure and diabetes. This is why it is so important to pick up a diagnosis of CKD as early as possible, because with a few changes the risk of progression of the disease can be reduced.


What do the kidneys do?

For two little organs that don’t often receive much in the way of attention, your kidneys are responsible for the life-saving role of filtering toxins from your blood. What many don’t realise however is that they are also involved in:

  • Regulating blood pressure
  • Maintaining a balance between fluid in and fluid out of your body
  • Red blood cell production
  • Activating the vitamin D that comes in from your diet so that it can be used by your body


How do kidneys get damaged?

The term “chronic” refers to a condition being long term. In the case of CKD, if a person’s kidneys are damaged and their kidney function is reduced for longer than 3 months, it is considered to be chronic.

The common causes of damage to the kidney (that can then lead on to CKD) include:

  • High blood pressure [link to BP page]
  • Diabetes
  • Taking medication that can be toxic to the kidneys (e.g. lithium, ciclosporin, non steroidal anti inflammatory medicines like aspirin and ibuprofen)
  • Obstructive kidney disease (e.g. recurrent kidney stones)
  • Multi-system diseases that can affect the kidneys (e.g. Lupus, myeloma, autosomal dominant polycystic kidney disease)


The complications of CKD

The complications that come with a declining kidney function extend to more than their blood filtering function. As kidneys are also involved in the maintenance of bone health and blood composition, as well as regulating blood pressure - untreated CKD can lead to:

  • Renal anaemia
  • Renal bone disease
  • Cardiovascular disease (increase in blood pressure, heart failure and peripheral vascular disease)

Many think of kidney disease and worry about kidney transplants or dialysis, but research has shown us that people with CKD are far more likely to be affected by an increase in heart disease than due to end-stage renal failure (CKD so severe that the kidneys stop working).


Who should get tested for CKD?

As mentioned earlier, the most common causes of CKD are diabetes and high blood pressure, so if you have either of those conditions your GP will be keeping an eye on your kidney function.

Other people who should have their kidney function checked include those with:

  • acute kidney injury (AKI) or a history of it
  • kidney stones
  • cardiovascular disease
  • multi-system diseases with potential effects on the kidney (Lupus, myeloma etc)
  • a family history of inherited kidney disease or severe kidney failure
  • medication that can cause kidney damage (i.e. people on long term non

steroidal anti inflammatory medications, diuretics, certain blood pressure tablets such as ramipril or losartan)

If you are unsure as to whether it would be good to have your kidney function checked or have any concerns after having read the above information, please discuss it with a GP.


How is kidney function measured?

A GP can assess and keep an eye on your kidney function in a variety of ways, including by:

  • Checking your blood pressure
  • Dipping your urine with a dipstick
  • Sending a urine sample to the lab
  • Requesting a “urea and electrolyte” (U&E) blood test - in particular looking at urea, creatinine, sodium and potassium levels

You might hear your doctor mention the “glomerular filtration rate”. This is the rate at which your kidneys filter blood. Usually your kidneys filter around 100ml per minute (about two thirds of a cup of tea) which adds up to an impressive 150 litres per day (that’s 2 bath tubs!).

Your glomerular filtration rate is calculated in the lab and takes into account your age, gender and creatinine level.

It is then expressed as a value between 0 and 100 mL/min/1.73m2 (the upper limit is sometimes given as ‘>90’). This number is then often used to determine whether someone has any acute or chronic kidney disease, in combination with sending a urine sample to the lab and dipping the urine in clinic with a urine dipstick.


Managing CKD

Most people with CKD can be looked after by their GP. Management involves keeping a regular eye on the kidney function and keeping the risks of cardiovascular disease as low as possible by managing blood pressure and cholesterol levels.

Some people require referral on to a nephrologist who is a consultant that specialises in kidney disease.


Lifestyle measures that can help

Whether you have a diagnosis of CKD or want to know how to keep your kidneys as healthy as possible, the following things can help:

  • Stopping smoking. Smoking has been shown to be associated with an increased risk of CKD worsening.
  • Taking regular exercise and keeping your weight in a healthy range.
  • Avoid using non-steroidal anti inflammatory medication if you have CKD unless advised by a doctor. This includes aspirin, ibuprofen and other similar drugs. Check with a pharmacist if buying medication over the counter.


References

  1. WORLD KIDNEY DAY. Are you kidney aware? [online] Accessed 1/3/2019