Consultant Nephrologist and lecturer in the Department of Medicine, Faculty of Clinical Sciences, Osun State University Teaching Hospital, Osogbo, Dr Titilope Bamikefa, tells EMMANUEL OJO the causes, management and prevention of kidney injury.
When is a kidney said to be damaged?
A kidney is said to be damaged or injured or a kidney is said to have failed when it’s unable to perform all the functions it is supposed to perform.
How important is this organ of the body?
The kidney helps regulate fluids and electrolyte balance in the body. It helps to remove toxic products of metabolism like urea from the body, whether it is exogenous or endogenous, which results from what we eat. It helps to maintain fluid homeostasis (balance) and to make sure that the amount of fluid in the body at every time is what is required. It does this by regulating urine formation. The kidney is also important in the sense that it helps to control blood pressure through some substances like bromine, which helps to maintain blood pressure. It also produces some hormones that help in keeping the bones mineralised like the active vitamin D which we need for calcium. It also produces erythropoietin which helps to keep the red blood cells in the right amount, just to make sure that the red blood cell is sufficient.
What are the different types of kidney injury?
When the kidney is failing to perform these functions (as stated above) for a day or hours, we say the kidney has failed acutely, so, we talk about acute kidney injury. If the injury has been ongoing for more than three months, we talk about a chronic kidney injury or kidney disease. So, the types of kidney injuries we have are acute kidney injury and chronic kidney injury or disease but acute kidney injury has to do with sudden deterioration in renal functions, leading to the inability of the body to handle wastes. As a result of that, both nitrogenous and non-nitrogenous wastes will be retained in the body and will also alter or affect fluid electrolytes in the body. So, for a kidney to have failed acutely, we have to look at so many parameters.
Acute injury was introduced in May 2004, to overcome the shortcomings of previous definitions because there has to be a consensus concerning the definition and diagnosis of acute injury. So, RIFLE (risk, injury, failure, loss and end-stage) kidney was introduced in 2004. However, there have been more modifications. So, if a patient has an acute injury, it means there is a sudden, often reversible injury. I said reversible because if it is handled on time, the injury does not progress to a chronic level, whereas for a chronic kidney disease, it tends to occur when there is irreversible damage to the kidney, which manifests in both structural and functional abnormalities, leading to the inability of the body to handle its wastes, which also affects foods and electrolytes homeostasis in the body.
What are the causes of the acute and chronic kidney injuries?
For acute kidney injury, we have to look at the various classifications. We have the pre-renal causes, those that are intrinsic renal injuries, and those that are post-renal causes. Usually, when you talk about pre-renal causes, it has to do with what happened before it gets to the kidney and most often than not, it is usually due to hypovolemia hypotension (low blood pressure). When there is a fluid loss that was not adequately replaced, it can cause renal injury.
Another thing that can cause it is hypotension. When the blood pressure becomes so low as a result of overwhelming or septic shock, when there is haemorrhage; trauma, when there is a road traffic accident, or when people lose a lot of blood, can also reduce the amount of blood that can get to the kidney from the cardiac output because the kidney receives about 20 per cent of the blood that the heart pumps. So, when the amount of blood that the heart pumps gets reduced, the amount of blood that gets to the kidney is also reduced. So, when this happens, the amount of blood that gets into the kidney is also reduced, and when this happens, it can be a prerenal cause of acute kidney.
Are there other things or diseases that can affect the kidney?
Other disease conditions too that affect the heart primarily, like congenital cardiac failures, can affect the amount of blood that gets into the kidney. These will cause injury to the kidney in the pre-renal cause. We call it the pre-renal cause of acute kidney injury. Other things that could cause it are substances that people take that could have toxic effects on the kidney. People that go over the counter at the chemist’s shop to buy medications are in this category. Others are people that take herbal medications indiscriminately because all of those things don’t have measurements; people just take the substance just the way they feel.
For pregnant women, when the pregnancy is not well managed and after delivery, they bleed, we call it postpartum haemorrhage. Anything that can cause loss of blood will affect the kidney. It’s a pre-renal type of acute injury. The other cause is intrinsic, meaning that the problem is within the kidney itself. They include glomerular diseases, vascular diseases, and epoxy diseases. Hypertension will also come under this classification.
What happens at the post-renal level?
In the post-renal cause, it means that the urine has been formed by the kidney, just to flow to the bladder and be released but there is an obstruction in the flow of the urine which can cause damage, so, that is caused by an obstruction in the flow of the urine. The causes of obstruction can include kidney stones and cancer, like prostatic cancer. Other causes can include tumours. For chronic causes, the commonest cause in this environment is hypotension. When one has hypotension and it’s not well curtailed, in the long run, it affects the kidney, causes renal necrosis and in the long run, causes major damage.
Is diabetes also a cause?
Another major cause is diabetes mellitus caused by the inculcation of westernisation and urban migration into our culture. If diabetes is not well managed, it affects the kidney. Another cause is glomerulonephritis, infections like HIV, and obstruction to the outflow of urine which can also be due to inflamed prostate in men. Other things are things that are preventable like sickle cell disease which could affect the kidney. Other causes include autosomal dominant polycystic kidney disease. These are some of the causes of chronic kidney disease within the environment.
Alcohol is identified as a substance that can endanger the body if taken indiscriminately. How does it affect the kidney?
Alcohol can cause cellular dehydration as a result of the way it works. Alcohol, directly and indirectly, can affect the kidney. It can dry up the cell within the kidney and affect the ability of the cell to control the balance of fluids and electrolytes.
It’s been observed that alcohol itself affects the structure and function of the kidney by causing some structural damage. Apart from that, alcohol damages the liver. All these are direct effects of the injury on the liver. It can cause liver cirrhosis which affects the kidney and in the long run, could cause hepatorenal syndrome. It can also cause ischemic heart disease which can affect the kidney in the long run. Alcohol can also cause hypotension.
What are the early symptoms of a damaged kidney?
As I said, acute and chronic kidney diseases are not a diagnosis, they are manifestations in the kidney. So, we have to look out for the causes of the damage to the kidney because when these things affect the kidney, there are some effects. For instance, when such patients wake up in the morning, there might be swellings in the face; we call it periorbital swelling. The face swells up in the morning but as the day goes by, the swelling is redressed. Another thing is when someone wakes up at night and urinates more than three times. We call it nocturia; that’s a common symptom that there may be a problem with the kidney.
Other things are fluid retention. So, if the patient is unable to maintain a fluid balance, the retention of the fluid can affect some parts of the body and it could affect the leg. Also, when a patient passes urine and the urine foams, it’s a sign that the patient is passing some proteins in the urine and those are part of the things that a patient should look out for to know that there is a problem. There can also be passage of blood in the urine which ideally, shouldn’t happen. There can also be fatigue due to anaemia. The kidney also helps in the absorption of calcium and mineralisation of the bones. So, when the kidney is affected, it leads to mineral-bone disease which can lead to pathological fracture of the bone. The urine production can also reduce over time to a point that the patient might not be able to pass up to 100mils of urine in a day; so, a reduction of the amount of urine is something to watch out for.
Are there other symptoms?
When a patient has had chronic disease for a long time, they can have features of palpitation. When the urea and other toxins that the kidney is supposed to help excrete from the body are not excreted, it can cause encephalopathy. A patient that is normal before can start behaving like a mentally-ill patient. They may become aggressive and some might have hiccups. When hiccups become too much, that could be a sign that the patient is dehydrated but after taking water and all that, it continues, the patient might need to go to the hospital. Some patients come down with respiratory distress. Some may even convulse.
Can kidney disease be inherited?
Yes, there are genetic causes of chronic kidney disease. One of them on the rise is autosomal dominant polycystic kidney disease.
How is it diagnosed?
On the diagnosis, when a patient comes to the hospital, the causes must be understood first as well as the symptoms that the patient could come down with. When these are understood, then it will be easy to diagnose. For instance, if there is blood loss and the patient starts giving signs of such, then, that’s a sign that the person has to come to the hospital. At the hospital, we do a lot of tests; we do electrolyte, urea and creatinine tests and analysis. We look at the kidney size and the number of red blood cells the person has. All of these will help us. For some, we do advanced investigation through a CT scan which will show us what the kidney structure is, especially, when there are speculations that the patient could have ADPKD, which will help to see if there are other cysts in the body like in the liver and the spleen.
So, all the investigative modalities will help us to confirm our diagnosis. We also check their calcium level, urea level, urine test to check for protein in the urine, check if there is blood in the urine and all that, all of these will help in our investigation. For some, we might put them through an electrocardiogram, to check the state of the heart and for others. We check the prostate and its size.
How can this condition be managed and prevented?
Once you have been able to make the diagnosis and have been able to put up the investigation modalities, the management aims to either prevent its progression, to also see if we can reverse what had happened and we don’t want complications in the system. If the patient comes with an acute kidney infection, you want to go after the cause and if the cause is loss of fluids, you want to replace fluids, if it’s due to loss of blood, you want to give blood. If it’s due to infection, you want to manage the infection to find out what is causing the infection and how to manage it. If it’s due to hypotension, you want to manage the blood pressure and see that it is well controlled. If it is due to diabetes, go after the diabetes.
What happens when the damage has occurred?
However, for some, the damage must have occurred. There may already be kidney disease on a chronic basis. For this group of patients, you don’t want the progression to be fast, you want to retard the progression, ensure that their blood pressure is well controlled, blood glucose is well controlled then avoid anything toxic to the kidney, like the use of herbal medications, indiscriminate use of analgesics and some drugs. There are some drugs that a patient with kidney disease should not take. They are not supposed to use any drug except their nephrologist recommends because their nephrologist has to guide them.
Herbal medication should also be avoided. Some patients, before they come to the hospital, would have tried several things and gotten recommendations from their friends and chemists. So, when these things happen, they should avoid taking drugs and herbal medications that are not licensed. Also, there will be lifestyle modifications, for those that need to reduce their weight, that will be done.
For those with kidney failure, they have to be supported on acute basis dialysis. There are various forms of dialysis and we have to decide which type suits the patient. Dialysis is a form of renal replacement therapy. However, for patients with chronic kidney diseases that are not reversible, we want to offer them renal faster dialysis which is the ultimate for patients with renal diseases.
So, kidney disease is an expensive disease to manage and the best way out is to try to prevent it, which could be primary, secondary, and tertiary – primary in the sense that you don’t even want the disease to happen. Also, genetic counselling, for those with genetic kidney disease; lifestyle modifications, reduction of the intake of refined sugars and regular exercise are important.
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