Kidneys – the master chemists of the body

Dr Sivakumar Sridharan

Consultant Nephrologist, Lister Hospital

Did someone say kidneys?

The two kidneys are located near the back muscles in the upper part of the abdomen – one on each side. The size of the kidneys range between 10 – 13cm depending on the body size, and they weigh around 150 grams each. Nearly 1.25 litres of blood flows through the kidney every minute, which enables it to filter and clean the blood many times a day.

Is it not just water that kidneys flush out?

While it is true that kidneys excrete excess water from the body, they also flush out a lot of unwanted toxins in the urine. These toxins are formed normally in the body, as a result of various chemical reactions within different organs, but can make you ill if they are not removed. Healthy kidneys are remarkable – they can completely remove these toxins at the right time, with as little as 600ml of urine per day. People with kidney failure have excessive amounts of many of these toxins in the blood, which means they become poorly and they can die sooner.

Kidneys don’t do anything else, do they?

The goal of the kidneys is to help maintain a perfect internal environment for all other organs to function healthily. In this context, getting rid of toxic chemicals in urine is only one of the many functions they do. While removing these unwanted toxins, they also ensure that essential chemicals are not lost in the urine and, instead, absorb them back into the blood. Kidneys are the main organs that prevent excess acid building up in the blood too.

Kidneys have a central role in maintaining a normal blood pressure. This is the reason why many kidney diseases can lead to high blood pressure. Kidneys secrete a hormone called erythropoietin, which prevents anaemia (where the blood can’t carry enough oxygen around the body). Kidneys produce the active form of vitamin D and so contribute to better bone health. Kidneys also play an important role in maintaining normal blood sugar levels. This means that some people with diabetes will need adjustments to their diabetes medications if their kidneys are not healthy.

Let us all focus on becoming more aware of kidney problems and the things we can do to prevent kidney disease and maintain healthy kidneys.

Kidneys are the master chemists.

Dr Homer Smith, an eminent kidney physiologist, once wrote*: “The composition of the body fluids is determined not by what the mouth takes in but by what the kidneys keep: they are the master chemists of our internal environment.” This sums up the importance of kidneys to good health.

Given the complexity and huge variety of functions that kidneys perform, it is unsurprising that even current modern technologies cannot replace all of these functions. As the old saying goes, ‘Prevention is better than cure’ – this is absolutely true with regards to kidney health. Let us all focus on becoming more aware of kidney problems and the things we can do to prevent kidney disease and maintain healthy kidneys.

The professional clinical charities of British Renal Society and the Renal Association are working together with the major kidney patient and kidney research charities (Kidney Research UK, Kidney Care UK, National Kidney Federation UK and the Polycystic Kidney Disease Charity UK) to raise awareness of how common kidney disease is and the vital role our kidneys play in maintaining health.