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Take care of your kidney and keep diseases at bay

World Kidney Day is celebrated on the second Thursday of March every year. The purpose is to raise awareness on the importance of our kidneys and to reduce the frequency and impact of kidney disease and its associated health problems worldwide.

Kidneys are a pair of bean shaped encapsulated organs, on both sides of the body, beneath the ribs and slightly to the back. Each kidney is about 10cm long, 5cm wide and 2.5cm thick, and weighs about 140g.

Their main function is filtering blood, removing wastes such as urea and nitrogen containing compounds and also regulating electrolytes and fluid volume within the blood vessels, and maintaining acid-base balance.

About 25 per cent of the blood leaving the heart goes to the kidneys. The structure of the kidney is the nephron, a structure which consists of a tuft of blood vessels (glomerulus) where blood is filtered and a renal tubule where water and electrolytes are reabsorbed from the filtrate. One human kidney has about one million nephrons.

About 120ml of glomerular filtrate is generated per minuite for a person with two normally functioning kidneys. Out of this, only 1-2ml of urine is produced at the end of the re-absorption process. This adds up to between 60ml and 120ml per hour, and an average daily urine output of about 1.5 litres.

The entire process of “cleaning” the blood and forming urine is regulated partly by hormones and also by the electrolyte and acid-base concentrations.

Kidneys are also important in the regulation of blood pressure through re-absorption of sodium and water, and also through a feedback loop that includes a hormone released by the kidney, and other hormones that act on the kidney.

The organ also plays a role in regulation of calcium and phosphate. It is the site of conversion of vitamin D into the usable form that helps in absorption of calcium from the intestines.

A calcium-regulating hormone (parathyroid hormone), also acts on the kidneys to minimise loss of calcium and phosphate in urine.

It is also the main site of production of erythropoietin, a hormone which stimulates bone marrow production and maturation of red blood cells. It also has a minor role in conversion of proteins into usable energy during starvation.

Disorders

Disorders of the kidney can arise due to any of the following: volume depletion due to dehydration or bleeding, low blood pressure, high blood pressure, heart and liver failure, damage to the kidney blood vessels or the kidney tissue by inflammation, infection, auto-immune disease, some medications (diuretics, NSAIDs, some anti-hypertensives, cancer treatment drugs), too much calcium or uric acid, some cancers, diabetes, alcoholism, toxins like lead and anti-freeze, and also any obstruction to outflow from the kidney e.g. due to kidney stones or enlargement of the prostrate.

Some disorders of the kidney are congenital (one was born with them).

Kidney disease manifests with a whole range of symptoms due to failure of its functions. 

The symptoms depend on the cause and duration of illness. These include abnormal urine volume (usually little or none) and composition, oedema due to fluid retention, high blood pressure to fluid and sodium retention, low calcium levels, anaemia and abnormal electrolytes.

When there is kidney failure, the blood level of urea and other nitrogen compounds rise, due to its impaired “cleaning” function. 

High levels of these compounds in the body are toxic, causing symptoms in all body systems including the brain, nerves and muscle, the blood, heart, lungs, gastro-intestinal system, the skin and even in bones. 

Occasionally, kidney failure can be reversed with dialysis if it had been a short illness. Chronic renal failure on the other hand requires dialysis every two days or a kidney transplant. 

The most common causes of chronic kidney failure are diabetes and hypertension. 

To maintain the kidneys in good form, eat healthy, take 1.5 to 2 litres of water daily, keep your weight in check, exercise, monitor blood pressure and sugar, avoid smoking, take alcohol in moderation, and do not take over-the-counter medication regularly, early detection and treatment of kidney disease.