There are several conditions and diseases that can eventually lead to chronic kidney disease (CKD).  Two of the most common conditions are diabetes and hypertension.  Of all the patients who have kidney failure, 43.5 percent have diabetes and 26.5 percent have high blood pressure.  The remaining 29.8 percent lost kidney function due to another condition.  This article describes the various diseases that can lead to CKD, with the two main causes - diabetes and hypertension - in more detail. Keep in mind that you are also at greater risk for kidney disease if you are African American and/or have a first degree relative (mother, father or sibling) with kidney disease.

Diabetes - Diabetes is a disease of high blood glucose (sugar) levels caused by either a reduction or lack of insulin in the body. High glucose can disrupt the structure and function of blood vessels. People with diabetes have an insulin deficiency, which results in abnormal metabolism of carbohydrates, fat and protein.  Over time, the small vessels of the kidney are affected, causing destruction of the filters of the kidneys.  

The high blood sugar can damage your kidney’s nephrons - the filtering system for your kidneys. To protect your kidneys, it is important to control your sugar levels. When kidneys are working well, the filters (nephrons) keep protein inside your body. You need the protein to stay healthy.  

High blood sugar and high blood pressure damage the kidneys’ filtering system. When the kidneys are damaged, the protein leaks out of the kidneys into the urine. Damaged kidneys do not do a good job of cleaning out waste and extra fluids. Thus, not enough waste and fluids leave the body as urine. Instead, they build up in your blood.  

An early sign of kidney damage is when your kidneys leak small amounts of protein, called albumin, into the urine. This is called microalbuminuria. As more and more protein is leaked, this condition is called proteinuria.  

If you have diabetes there are ways you can slow or even prevent diabetic kidney problems:  
• Keep your blood sugar as close to normal as you can.
• Keep your blood pressure below 130/80. Keeping your blood pressure under control will also slow damage to your eyes, heart and blood vessels.  
• Follow the healthy eating plan you work out with your doctor or dietitian.  
• Have your kidneys checked at least once a year by having your urine tested for protein.  

Hypertension- High blood pressure (hypertension) is a condition that can damage your kidneys. Your kidneys act like a filtering system to get rid of excess water and wastes in the blood. Blood pressure is the force, or pressure, of the blood on the walls of your blood vessels. Over time, uncontrolled high blood pressure can damage the blood vessels and nephrons in the kidneys. The damaged nephrons cannot do their job of filtering out all the wastes, sodium and excess fluids from your blood. The excess fluid and sodium stay in your bloodstream putting extra pressure on the walls of your blood vessels - raising your blood pressure even more. The extra pressure leads to further kidney damage.

Blood pressure is the force of blood inside the artery. The readings are made up of a systolic number (the top number) and a diastolic number (the bottom number). The systolic blood pressure is when the heart beats and the diastolic blood pressure is when the heart is at rest.  A blood pressure reading consists of the upper number and a lower number. As an example, this is stated as “120 over 80 or 120/80.”  The joint National Committee on the Prevention, Detection and Treatment of Hypertension states that blood pressure for patients with protein in their urine should be controlled to 130/85 mm Hg or lowered to 125/75 mm Hg. This can help preserve kidney function and protect the kidneys from further damage.  

If left untreated, high blood pressure can damage the inner lining of the blood vessels. This is called atherosclerosis. High blood pressure increases the workload on the heart. It can also affect the heart’s pumping ability and may lead to heart failure. High blood pressure increases the risk of coronary artery disease, aneurysms, stroke, kidney disease and eye problems.

The strategy to control blood pressure is to use medicines that have additional benefits. Angiotensin is a hormone your body makes that constricts smooth muscles in the vessels of the kidney and in other vessels as well. There are two types of drugs that can block this hormone: angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs). ACE inhibitors decrease your blood pressure by opening or dilating blood vessels. ARBs work by blocking the hormone that causes blood vessels to narrow. Both types of drugs have been shown to help reduce the progression of kidney disease, especially in diabetics.

Since the target blood pressure required to help protect the kidneys is often lower than you can achieve with one drug, your doctor may have you take additional medications. Your doctor may also prescribe a diuretic for you. Diuretics are used to remove extra sodium and fluid from the body. Eliminating excess fluid may lower your blood pressure.

Other conditions include:

Glumerulonephritis - This is an inflammation of the filters of both kidneys. This is sometimes due to infection. It involves slow, progressive damage. Early diagnosis is difficult because there are minimal symptoms in the early stages of the disease.

Nephrotic Syndrome - Nephrotic syndrome causes amounts of protein to pass from blood into urine. As a result of the loss of protein, large amounts of water stay in your body. This results in overall swelling in your body, called edema.

Polycystic Kidney Disease (PKD) - PKD is an inherited disease in which abnormal sacs, called cysts, develop in the kidneys. These cysts may contain fluid, gas or tissue. As these cysts grow, they block normal kidney function. Cysts may be painful because of the blockages. Cysts can get infected and can bleed. If you have PKD, you will still urinate in normal amounts, but the harmful waste products are not removed from the body.

This article originally appeared in the September/October 2003 issue of Kidney Beginnings: The Magazine, Vol. 2, No. 3.

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