What exactly does the kidney do?
The kidney has many functions and we will discuss some of them in more detail. Many of the functions of the kidney are reflected in some of the blood work we order. We will explain what some of the blood tests mean as well.
1) Toxin elimination – every day that you live and breathe, your body generates toxins. These are waste products of metabolism. One of the functions of the kidneys is to eliminate these toxins. One of your blood tests called “BUN” is a rough measure of toxin level. Don’t be surprised to see that it is elevated as it is elevated in all patients with chronic kidney disease (CKD). A normal level is less than 20. A high level of toxin can lead to loss of appetite, nausea, vomiting, and itching and weight loss. It can also lead to confusion and seizures.
2) Potassium balancing – potassium is a mineral that is essential for many things. A level that is too low can promote progression of kidney disease and a level that is too high can cause abnormal heart rhythms. A normal level is generally 4 and 5.5. If your level is high, you will be counseled in a low potassium diet.
3) Salt and water elimination – your kidneys helps regulate blood pressure, and high blood pressure is not only a cause of kidney disease but also promotes kidney disease progression. One of the ways that the kidney helps regulate blood pressure is by eliminating salt and water. You will recognize that your body contains excessive salt (sodium) when your blood pressure is high or if you notice swelling in the ankles or legs. This is called “edema”. Almost all patients with chronic kidney disease should be on a low sodium diet.
4) Bone Health – your kidneys help to maintain bone health by activating vitamin D and by balancing the amount of calcium and phosphorus in your body. When you have kidney disease, you become deficient in vitamin D and you tend to become deficient in calcium. You also will have a tendency to accumulate too much phosphorus in your body, which not only results in bone disease but also heart disease. Excessive phosphorus can also make your kidney disease progress faster. We usually supplement patients with vitamin D. We will also monitor your calcium and phosphorus levels.
A normal calcium level is between 8.7 and 10, while a normal phosphorus level is between 3.5 and 4.5. There is also a hormone that becomes overactive with chronic kidney disease called parathyroid hormone, or PTH. The level of this hormone rises with kidney disease. Too much of this hormone will also cause bone disease. We will measure this hormone as well. We can lower the level of this hormone by keeping the phosphorus and vitamin D levels normal. A normal PTH level is usually less than 100.
5) Neutralizing acid – every day your body generates acid, not only in the stomach but also in the blood stream. This acid is neutralized by something called bicarbonate. Bicarbonate is made by the kidneys. With chronic kidney disease, your kidneys may not make enough bicarbonate, and acid will then build up. This is reflected by a low bicarbonate level. We call this an “acidosis”. This can lead to bone disease and shortness of breath. It can also promote progression of kidney disease. A normal bicarbonate level is 22-30. If your level is low, your nephrologists may elect to place you on bicarbonate pills.
6) Maintenance of normal blood count – your kidney produces a hormone called erythropoietin. This hormone stimulates your bone marrow to make red blood cells. This is reflected in a blood test called “hemoglobin”. When your kidneys are diseased, they don’t produce enough erythropoietin and therefore your bone marrow will make fewer red blood cells. This will lead to low hemoglobin. You may then experience shortness of breath, lack of energy, dizziness and feeling cold all the time. A normal hemoglobin is greater than 12.5 in women and 13 in men. If your hemoglobin drops below 10, you will then be placed on a medicine called Procrit or Aranesp. These are injections designed to increase your hemoglobin.
How do I know if I have kidney disease?
Unfortunately, you can lose 80-90% of your kidney function and experience NO symptoms. Kidney disease is usually diagnosed in one of the following ways:
1) An abnormal imaging study such as ultrasound, CT scan or MRI: These studies may indicate kidney disease by showing small kidneys, scarred kidneys or obstructed kidneys
2) An abnormal urinalysis which shows protein: Protein in the urine reflects kidney damage. In addition, the more protein there is in the urine, the greater the chances that the kidney disease will progress over time. Protein in the urine not only reflects kidney damage, it is now thought to cause kidney damage as well. It will be one of our goals therefore to try and reduce the amount of protein in the urine.
3) An abnormal urinalysis showing blood in the urine: Blood in the urine can be due to many things such as kidneys stones or tumors. It can also indicate inflammation in the kidney.
4) An elevated creatinine: Creatinine is a waste product produced by your muscles that is removed by your kidneys. A normal value is around one (1). When your kidneys don’t work properly, the level of creatinine in the blood will begin to rise. Dialysis or transplantation is usually needed once the creatinine goes above six (6).
5) An abnormal “GFR”: GFR is a value that more accurately indicates kidney function than creatinine. A normal value is around one hundred (100). The lower your GFR, the greater the amount of kidney damage. To put things in perspective, we have different goals depending on the level of GFR. When the GFR is relatively high, our goals are to diagnose the cause of the kidney disease and try to slow the progression.
Once the GFR drops below sixty (60), our goals then include watching for complications of kidney disease such as bone disease, anemia and acidosis that were discussed earlier. Once the GFR drops below thirty (30), then we start to talk about the prospects of transplantation and dialysis. Education will be very important at this stage.
Once the GFR drops below twenty (20), then you will be prepared for dialysis and transplantation. Once the GFR is below ten (10), in most cases, you will be started on dialysis, unless you can be transplanted first. However, it should be understood that just because your GFR is below ten (10) does NOT mean that you must be started on dialysis. If you are feeling well without any symptoms, if you are not losing weight and if your blood work is otherwise reasonable, we may elect to delay starting dialysis. It must also be understood though that you have to be ready for dialysis at this stage with a functioning shunt in place which we will discuss later.
What can be done to treat chronic kidney disease?
1) Strict blood pressure control – controlling your blood pressure is perhaps the most effective way to slow or halt the progression of chronic kidney disease. Not only will it help with kidney disease, it will also help prevent heart attacks, strokes and congestive heart failure, 3 major causes of death for patients with chronic kidney disease.
Our target blood pressure is less than 130/80. In addition to taking your blood pressure medication, there are additional lifestyle changes that YOU can make to help with your blood pressure and kidney disease. One important way is with diet. A low sodium (salt) diet is extremely important for patients with chronic kidney disease. Another way is with weight loss. Weight loss is not only important for blood pressure control, but it will also help decrease protein in the urine (one of our targets of treatment), lower cholesterol, and decrease blood sugars, lessen stress on joints and also help if you have sleep apnea.
Finally, exercise is also important for similar reasons. We would recommend a vigorous walk of at least 30 minutes a day. We would also recommend you monitoring you blood pressure at home with you own blood pressure cuff. Studies have shown that blood pressures that are obtained at home are a better reflection of your blood pressure in general than that obtained in the doctor’s office.
2) Stopping smoking – smoking has been shown to accelerate chronic kidney disease in addition to its other risks including heart disease, stroke, emphysema and various cancers including lung and kidney cancer.
3) Cholesterol control – lowering cholesterol with an LDL target of less than 100 (LDL cholesterol is the “bad” cholesterol) is important not only for your kidneys but also for preventing heart attacks and strokes, two leading causes of death in patients with chronic kidney disease. Your primary care doctor will work with you on this target.
4) Diabetes control – keeping your sugars under control is also very important. Our recommended target is a hemoglobin A1C less than seven (7). (Hemoglobin A1C is a blood test that tells us how well your sugars are controlled. The lower the number, the better). Your primary care doctor will work with you on this target.
5) Lowering the protein in your urine – this is best done with blood pressure control, weight loss and through the use of specific medications called ACE inhibitors and ARBs. These are blood pressure medications that lower protein in the urine and also help slow the progression of chronic kidney disease. One side effect of these important drugs is the raising of your potassium level. Therefore, your potassium level will have to be closely monitored on these medications.
6) Minimizing alcohol – drinking excessively will increase your blood pressure, further damaging your kidneys. It is recommended that women limit that alcohol intake to one drink a day and men to two drinks or day. In addition, homemade alcohols such as moonshine and corn liquor contain lead, which will further damage your kidneys. These types of beverages should be totally avoided.
7) Avoiding certain over-the-counter medications and herbal medications – some over-the-counter medications such as Sudafed (pseudo-ephedrine) can raise blood pressure. Pain killers like Advil (ibuprofen), Motrin (ibuprofen), Aleve and Nuprin can increase blood pressure, cause fluid retention and raise potassium. They can also directly damage the kidneys, especially if taken daily. Tylenol is probably the safest over-the-counter pain medication you can take if needed. You also should be aware that certain herbal medications can damage the kidneys.
What should I expect? What are the symptoms of chronic kidney disease?
1) As mentioned previously, one of our goals is to try and halt the progression of your disease. Despite this, some will experience a progression of disease. As also mentioned previously, you can lose up to 90% of your renal function before you experience any symptoms, and you can even make a great deal of urine despite advanced disease. The symptoms that you may experience include loss of appetite, nausea, vomiting (especially when first getting up), fatigue, feeling cold all the time, irritability, sleeplessness at night, itching, twitching, confusion, and seizures. The last three symptoms indicate very advanced disease. More commonly, you may notice that when you feel hungry, the food will be served and then you will not want to eat it. You may notice that certain foods, such as meat, will especially turn you off. You may also notice that the food loses its taste, and you may notice a bitter or metallic taste in the mouth.
2) Once your GFR drops below thirty (30), you will be sent to an education class run by one of our nurses. In this class, you will learn about chronic kidneys disease and options should your kidneys fail, including transplantation and dialysis. This education is extremely important for you and your family and is free of charge. We strongly urge you to attend it. This doesn’t mean that you are close to needing dialysis. Rather, it is an attempt to educate you about your options in advance.
What are my options should my kidneys fail?
1) Transplantation: For most patients, transplantation is the best option. Transplantation allows you to live a longer and better quality of life. When your GFR drops below twenty (20), you will be referred to a transplant center for evaluation. This evaluation will educate you about transplantation as well as its risks and benefits. You will speak with a nurse, social worker, transplant surgeon and a nephrologist. You will have your blood drawn as well. The evaluation usually lasts for about two hours.
It is important to know that there are two types of kidneys that can be transplanted. One is from a family member, friend, spouse or anonymous donor. This is called a living-donor kidney for obvious reasons. A living-donor kidney is the best type of kidney to receive as it will usually work right away and will last longer. Most important, it can allow you to avoid dialysis entirely.
The other type of kidney is called a cadaveric kidney because the donor is someone who has died. This type of kidney may not work right away and may not last as long as a living kidney. The average wait in Philadelphia for a cadaveric kidney is about 3-4 years. More than likely, due to this wait, you will need to go on dialysis if your kidneys are failing before you receive this type of kidney. It is important to be evaluated early so that you can get on the list as quickly as possible.
2) Dialysis: For most patients who have failing kidneys, dialysis is the only form of treatment until they are transplanted. It is important to realize what dialysis does and does not do. It DOES replace the function of failing kidneys. It DOES NOT treat failing kidneys. Dialysis does what the failing kidneys cannot do: it removes toxins, certain electrolytes, removes acid from the bloodstream and removes excessive fluid. It helps to improve appetite, breathing and blood pressure. It allows you to live. It is a major change of life for a patient and involves a major commitment from the patients, their families and their physicians. It is a major life change, and it is not unusual for patients to feel depression and anger during this time.
However, as time goes on, and the patient has adjusted to the new constraints, most feel that they have a good quality of life. It is also important to know that there are several types of dialysis, including in-center hemodialysis (the most common), home hemodialysis (hemodialysis done at home), nocturnal hemodialysis (hemodialysis done overnight, either in a center or at home) and peritoneal dialysis. We will discuss each hemodialysis and peritoneal dialysis.
Hemodialysis
Most hemodialysis is done in a dialysis center or clinic. It can also be done at home or overnight. If can also be done by you in-center (this is called self-care). Hemodialysis involves hooking a patient up to a hemodialysis machine. The hemodialysis machines filters and cleanses the blood. It then returns it to the body at the same time. Each treatment generally lasts about fours hours and is done three times a week, Monday, Wednesday and Friday, or Tuesday, Thursday and Saturday. The treatments occur at the same time and in the same place at the dialysis facility, which hopefully will be close to where the patient lives. In order to hook the patient up to the machine, a fistula or graft needs to be placed in the patient’s arm ahead of the time when hemodialysis is anticipated to take place.
A fistula is a type of shunt that is placed in the arm. It is created from an artery and a vein by the surgeon. There is no foreign material. The veins will then dilate over several weeks. These enlarged veins then are used to connect the patient to the hemodialysis machine via two large needles. It usually takes about
8 weeks before the fistula can be used for hemodialysis. The advantages to a fistula are 1) they rarely clot off, 2) they rarely get infected and 3) they can last several years. The major disadvantage is that only about 50% of them can be used 8 weeks after placement. This means that in the other 50% of the time they have to be surgically revised. This is why they need to be placed at least 6 months before hemodialysis is anticipated to start. This gives us plenty of time to fix the fistula if needed. Despite this disadvantage, a fistula is by far the hemodialysis access of choice. Before we send you to a surgeon to have one placed, we will set you up for something called “vein mapping” which is a type of ultrasound and x-ray test to see if the veins in your arm are large enough to allow for the creation of a fistula.
The other type of shunt that is often created is called a “graft”. A graft is a tube, somewhat like a piece of a garden hose, which connects an artery to a vein. Think of it as a large artificial vein that is placed under the skin. The advantages to a graft are that they can be used right away, usually within 2-3 weeks, and that they usually don’t require surgical revision, unlike fistulas. There are however several major drawbacks to grafts. One is that they are prone to clot off. When this occurs, then we need to send you to what is called an “access center” to have them unclotted. The second drawback is that they are also more likely than fistulas to get infected. The third drawback is that they only last on average 1-2 years, unlike fistulas which usually last much longer. Grafts overall are an inferior access compared to fistulas.
The third type of access, and by far the least optimal, is a catheter. Catheters are usually placed in the right jugular vein right below the neck. They are then tunneled under the skin and exit the skin on the chest wall. They can be used right after placement and don’t require needles to hook the patient to the hemodialysis machine. However, they are very prone to infection, function poorly and can cause collapse of the major veins in your chest. This can lead to facial and arm swelling. There is also an increase in mortality in patients who are dialyzed through catheters compared to fistulas and grafts. We therefore should make every attempt to avoid this type of access.
As mentioned earlier, hemodialysis treatments generally last about 4 hours. During the treatment, patients may experience nausea, headaches, leg cramps, dizziness, palpitations and drops in blood pressure. After the treatment they may feel very tired and “washed out”. Some patients will experience these symptoms often while others may never experience them at all.
Peritoneal Dialysis
Peritoneal dialysis is a form of dialysis that can be done at home. It consists of having a catheter placed into the abdomen. Fluid is then placed into the abdomen through the catheter. This fluid then sits in the abdomen for a couple of hours or more. While in the abdomen, the fluid draws out toxins and excess fluid. After it has been in the abdomen for a couple of hours, it is then drained and discarded. This procedure of filling the abdomen, letting the fluid sit, then draining the fluid, is repeated several times a day. This can be done manually about 4-5 times daily (this is called CAPD), or it can be cycled overnight via a machine that will automatically fill and drain the abdomen while the patient sleeps (this is called CCPD). CCPD allows the patient to be free of dialysis during the day and is therefore ideal for a patient who works.
Peritoneal dialysis, unlike hemodialysis, must be done every day. The advantages are that patients have fewer swings in fluid balance and therefore don’t feel as drained after their treatments. It affords more freedom and control. One disadvantage is that the fluid that is instilled in the abdomen can become infected if the patient doesn’t observe proper sterile technique (this is called peritonitis). Peritonitis usually can be treated on an outpatient basis. In addition, the fluid contains a great deal of sugar and can drive up blood sugars if the patient is diabetic. All in all, there is no major advantage or disadvantage of peritoneal dialysis over hemodialysis.