Why does kidney disease increase your risk?

The kidneys help to control and maintain your body’s chemical balance. For example, the kidneys make hormones that regulate the electrolytes and fluid balance. Hormones such as renin and angiotensin control how well the blood vessels expand and contract so the kidneys play an important role in maintaining healthy blood pressure.

If your kidneys aren’t working properly your blood pressure can rise. If high blood pressure is left unchecked it tends to thicken the blood vessel walls causing blood vessels to narrow. High blood pressure can also damage small blood vessels taking blood to the kidney filters and the filters themselves. Severe, uncontrolled blood pressure weakens the heart muscle, enlarges the heart and can cause kidney failure.

Your kidneys control the acid level in your body plus the levels of minerals and salts such as potassium, chloride, bicarbonate, phosphate, sulphates, magnesium, sodium (salt), calcium and potassium. These minerals and salts are called electrolytes.  Electrolytes are found in the food tand fluids we consume. Electrolytes are important as they keep you healthy, but too much or too little can make you sick. For instance, if you have too much sodium your body retains water. Repeated fluid overload can damage your heart. Too much potassium may cause an abnormal heart rhythm and not enough magnesium can affect heartbeat and change mental state.

The balance of calcium and phosphate levels in blood is also upset by chronic kidney disease. This eventually causes calcium deposits to build up in your blood vessels and heart also known as atherosclerosis. Poor control of calcium and phosphate levels increases the risk of cardiovascular disease over time. 

CKD often causes anaemia, a serious disease leading to other health conditions if left untreated. For example when the numbers of red blood cells drop, your heart works harder to maintain oxygen levels. If the heart works too hard, the heart muscle becomes larger and can lead to heart failure.

If your kidney damage is caused by diabetes, you are at a much higher risk of CVD because diabetes also affects the heart and blood vessels. Good control of blood glucose and blood pressure levels is essential.

We recommend our publications -  Kidney Health and Blood Pressure,  Chronic Kidney Disease, All about Anaemia, Calcium and phosphate, Kidney Health - What you should know and webpage Diabetes and CKD

What is normal blood pressure?

Since blood pressure varies from person to person and for each person during the day, there are no fixed rules about what blood pressure reading is ‘normal’. These figures can be a useful guide:

• Normal < 120/80
• High normal 120–139 / 80–89
• High > 140/90

How does your blood pressure Measure Up? 

A single high reading is not enough to make a diagnosis of ‘high blood pressure’. You need to have a series of high readings taken on several different days, at different times, before high blood pressure - often called ‘hypertension' can be confirmed. Your blood pressure does not stay the same, it changes to meet the demands of your body. It is usually at its highest when we exercise and lowest when we sleep. It can also rise due to anxiety, excitement, activity or nervousness.

Is high blood pressure related to kidney disease?

Although some people with high blood pressure can get headaches, dizziness or nosebleeds, high blood pressure does not always give warning signs. Often high blood pressure is found accidentally. The only way to know if your blood pressure is high is to have it checked regularly by your doctor. You may have high blood pressure and feel perfectly well.

The causes of high blood pressure can vary. In 90% of cases, no underlying cause is found. Some people are at greater risk of developing high blood pressure than others. These factors can also increase the risk of high blood pressure or make its effects more serious:

• older people
• people with a family history of high blood pressure
• people who are overweight
• and smoking
• high cholesterol
• too much fat and salt in the diet
• over use of alcohol and
• not enough physical activity  

High blood pressure can occasionally be caused by a problem in an endocrine gland, such as the adrenal gland. These cases are fairly rare and can be cured by treatment. Certain drugs such as birth control pills, decongestants and diet pills can also raise blood pressure. Your doctor can give you advice on these issues.

If high blood pressure is left unchecked, it can cause blood vessels in your kidneys to become thickened and narrowed. This can affect your blood supply to the kidneys and, as a result, your kidney function. Uncontrolled blood pressure may cause severe or total kidney failure. High blood pressure can develop as a result of almost all kidney diseases. A narrowing of the main artery to one or both kidneys can also cause high blood pressure; this is called renal artery stenosis.

Salt intake and high blood pressure

The kidney was designed to balance the salt intake naturally occurring in foods with body needs. Eating as we do, many people accumulate more salt and water than their kidneys can handle. Excessive salt also exerts excess pressure on our heart’s blood vessel walls. The higher the blood pressure, the more blood flow to the kidney is reduced, impairing the function of the kidney and ultimately leading to chronic kidney disease. If you have kidney failure, salt and fluid retention can also cause high blood pressure.

A healthy diet with salt reduction to roughly less than five grams (100 mmols sodium) substantially lowers blood pressure. In addition, measuring blood pressure regularly and using medications when necessary are vital to reducing the incidence and risk of chronic kidney disease. More info at Australian Division of World Action on Salt and Health (AWASH)

Refer to New England Journal of Medicine publication (Volume 344:3-10 January 4, 2001 Number 1)  'Effects on Blood Pressure of Reduced Dietary Sodium and the Dietary Approaches to Stop Hypertension (DASH) Diet' which has been proven to help lower blood pressure. Or for a more understandable outline, you may prefer info from the National Institutes for Health USA 'In Brief: Your guide to lowering your blood pressure with DASH'

How do medications help to reduce CVD?

Medication should only be taken as advised by your health care team  Managing your medication is an important part of treatment.  Your doctor may prescribe a variety of medications to treat CKD, most are designed to control blood pressure and help regulate the body's chemistry.

To prevent unwanted side effects, it is important to tell your doctor about all your medications including those sold over-the-counter such as vitamins and herbal supplements. Ring Medicine Line (1300 888 763) for independent pharmacist advice on prescriptions, over-the-counter, and complementary (herbal/natural/vitamin/mineral) medicines.

Each medication is given for a particular reason and should be taken as directed. Never change a dose or stop taking a medication without your doctor’s approval.  Some medications your doctor may prescribe are:

Cholesterol or lipid (fat) lowering medications  For the general population, the recommended level of total cholesterol is no higher than 5.5mmol/litre. However for people with chronic kidney disease, diabetes and in other high-risk groups for CVD, the recommended level is less than 4. This lower target is often difficult to achieve without medication. Various medications can lower cholesterol levels. Not everyone takes the same type of blood lipid medication and often a combination of drugs is used. One common drug is called a statin. Statins lower LDL cholesterol and triglyceride levels and boost the HDL levels.

Blood pressure medication Good blood pressure control can slow the progression of chronic kidney disease, delay the need for dialysis, maintain your heart health and increase the life of a transplant. If you have chronic kidney disease, your blood pressure target is 130/80. Different types of blood pressure tablets work in different ways, so it is not unusual for more than one type to be prescribed. The dose may alter according to your needs.

Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARB)  In recent years these medications have been used to keep your blood vessels opened and relaxed. ACE and ARB prevent a hormone called angiotensin from forming and narrowing your blood vessels. Both these medications also help protect your kidney function.

Other medication called beta-blockers  Helps to lower blood pressure by allowing it to beat slower and less forcefully.

Calcium-channel blockers  Help the blood vessels to relax by keeping calcium out of your blood vessels and heart. A diuretic or water pill is often prescribed as well as it helps rid your body of extra fluid and sodium through your urine.

Phosphate binders  Your doctor may prescribe a medication called a phosphate binder to take with your meals and snacks containing phosphate. This is given to lower the amount of phosphate absorbed from the food you eat. Phosphate binders are taken with food and act by trapping the phosphate in the gut before it has a chance to move into the blood. There are several types of phosphate binders.

Erythropoietin (EPO) is used to treat anaemia  It can be given as an injection on a weekly, fortnightly or even monthly basis depending on your blood results. The dose varies from person to person. Your doctor uses the level of haemoglobin in your blood and your body weight to decide on the dose. EPO can cause high blood pressure but it is better to treat blood pressure than to stop taking this medication.

Bicarbonate supplement  Occaisionally necessary to treat acidosis.

Aspirin  Low doses of aspirin may be given to improve blood circulation. Caution should be taken if aspirin is used by people on dialysis or post transplant.

How can you reduce your risk of CVD?

The best way to reduce the risk of CVD is to control and maintain a healthy blood pressure, cholesterol level and blood glucose level if you have diabetes. If you have CKD this usually means using medication as well as having a healthy lifestyle. Identifying chronic kidney disease early and slowing the progression to end-stage kidney failure as well as reducing other risk factors is important in reducing your risk of CVD. It is important to take control of your own health. Talk to your health care team to get practical advice about the best way to reduce your risk of CVD.

Do healthy lifestyle choices help to reduce CVD?

The role of our kidneys is often underrated when we think about our health. Although only small organs, the kidneys are responsible for removing waste and fluid from the body, helping to control blood pressure, assisting with the production of red blood cells, and helping to keep our bones strong. You can lose up to 90 per cent of kidney function without realising it, by which time it is almost impossible to prevent further serious problems. Be kind to your kidneys - take positive measures to avoid this diagnosis.

Healthy lifestyle choices - can help to improve your overall health, may lower your risk of CVD, can reduce the amount of medication you need, or make your medication work better. There are a number of ways you can reduce your risk of kidney disease:

• Being a non-smoker
• Eating a healthy diet with plenty of fruit and vegetables plus low in salt and saturate fat unless otherwise directed by your doctor
• Staying fit by doing at least 30 minutes of physical activity on most days of the week
• Maintaining a healthy weight
• Doing things that help you to relax and reduce stress
• Drinking alcohol only in moderation
• Avoiding certain medications

It is important to take control of your own health  Talk to your health care team to get practical advice about the best way to reduce your risk of CVD. Refer to our webpage Measure Up and CKD.

Why does cholesterol increase your risk?

Cholesterol is a type of fat or lipid, which the body needs to stay healthy. It is not necessary to eat foods that are high in cholesterol as your body is very good at producing its own. To help keep your heart healthy it is important to keep your bad (LDL) cholesterol low and your good (HDL) cholesterol high. Your total cholesterol is made up from the LDL and the HDL cholesterol. The total cholesterol level recommended for heart health for adult Australians is 5.5 mmol/L or lower.  There are two types of cholesterol, which is a white and waxy substance:

• Low-density lipoprotein (LDL) cholesterol – you need a small amount of LDL but sometimes it is called the 'bad' cholesterol because the excess goes into the bloodstream and clogs up your arteries.
• High-density lipoprotein (HDL) cholesterol - called the 'good' cholesterol because it helps to take the LDL cholesterol out of the bloodstream.

Triglycerides are the most common form of stored fat in your body. Usually only a small amount is found in your blood. Triglycerides may not cause fatty deposits in your arteries but are often linked to low HDL or a tendency towards diabetes. Both increase your risk of CVD.

If you have diabetes your LDL particles are unusually small and dense, which can be more harmful to blood vessels. Your triglycerides and HDL levels are often too low so people with diabetes are at higher risk of CVD.

Can diet reduce your cholesterol?

You can reduce your cholesterol level using a combination of medication and dietary changes. It is very important to talk to your doctor or a dietitian experienced in kidney disease before making any changes to your diet. Your eating plan has to be designed with your special needs in mind. If you are on dialysis, you could be asked to limit your salt, phosphate, potassium or fluid intake but only if these are causing problems. Some people have to take supplements. People with kidney transplants have a much less restricted diet. Dietary cholesterol often comes from saturated fats that are found mostly in animal products.

These are some dietary tips:

• Limit the amount of cholesterol-rich foods you eat
• Eat plenty of fresh fruit, vegetables and wholegrain foods - these are high in fibre and may improve your blood lipid levels
• Include foods in your diet that are rich in soluble fibre and healthy fats, such as nuts, legumes and seeds
• Choose low or reduced fat milk, yoghurt and other dairy products or have 'added calcium' soy drinks.
• Choose lean meat (meat trimmed of fat or labelled as 'heart smart')
• Limit fatty meats, including sausages and salami and choose leaner sandwich meats like turkey breast or cooked lean chicken
• Have fish (fresh or canned) at least twice a week
• Replace butter and dairy blends with polyunsaturated margarines
• Use only unsaturated cooking oils labelled as 'polyunsaturated' or consisting of canola or olive oils
• Use only small amounts of oil and margarine in food preparation and cooking
• Be aware that some nuts such as brazil and macadamia are high in saturated fats

Why is exercise important?

Regular physical activity or exercise can help lower your risk of CVD by:

• Lowering your ‘bad’ and increasing your ‘good’ cholesterol
• Reducing your triglyceride level
• Improving fitness of heart and lungs
• Helping to maintain a healthy weight
• Helping to control blood pressure and blood sugar

In the beginning, a chat with your doctor is a good idea to make sure there is nothing to stop you exercising safely.  The key is to start slowly and gradually increase the time and intensity of your activities. Physical activity leads to increased strength, stamina and more energy. If you are only starting out, aim to do some physical activity for at least 30 minutes, 3-4 times weekly. The 30 minutes can be broken down into smaller blocks, e.g. 3 x 10 mins, which can be increased as you become fitter. Refer to our Measure Up and CKD webpage.

It is important to stop exercising and tell your health care team if you get:

• Chest pain or pressure
• Dizziness or light-headedness
• Irregular or fast heart rate that persists when the activity is completed
• Excessive shortness of breath