Kidney Disease and Dehydration

The effect of chronic dehydration on the kidneys

Each person has two kidneys. Each kidney contains millions of specialized structures called nephrons. The nephrons filter blood through the glomerulus in order to excrete waste products in urine and regulate the water and salt balance in the body. Each kidney filters 8 liters of blood per hour, and 90% of it is reabsorbed by the tubules in the nephrons. Common causes of kidney disease are high blood pressure, diabetes, drugs, urine tract infection and glomerulonephritis or inflammation.

Chronic dehydration can also lead to kidney disease. Because the kidneys are so actively filtering and reabsorbing blood, they require a good blood supply in order for the cells to get enough oxygen for energy. When a person is dehydrated, blood flow to the kidneys is reduced. This can result in damage to the cells in the tubules of the nephrons in the kidneys. This condition is known as acute tubular necrosis (ATN).

When the kidney is damaged, the markers of kidney damage, creatinine and urea, are found to be elevated in circulating blood. The glomerular filtration rate (GFR) is reduced. Urine output is decreased. Severe kidney disease can also cause the person to feel unwell, weak, nauseous and lose appetite.

Kidney disease caused by dehydration can usually be reversed by rehydration. Increasing the water content in the body results in more blood flow to the kidneys and the tubular cells recover.

Chronic dehydration also results in kidney stones. Stones form when salts precipitate and form crystals. These can happen in the kidney, the bladder or anywhere along the ureters which connect the kidneys to the bladder. Kidney stones can block the flow of urine from the kidney to the bladder. When this happens, there is a back pressure of urine on the kidney, resulting in damage to the cells of the kidney. This kind of kidney damage usually happens after a long time of blockage by the stone and is usually irreversible.

Kidney disease can lead to death. Because the kidneys play such an important role in the body, life cannot be sustained without having functional kidneys. People with chronic kidney disease have to be hooked up to dialysis machines daily or at least a few times a week in order to live. They also suffer from complications such as bone disease, anaemia and increased risk of heart disease.

Therefore, keep your kidneys healthy by drinking enough water (at least 8 glasses a day) to avoid dehydration.