Weighing at just around 160 gram each, the kidneys perform an incredible job of filtering between 180 and 200 liters of blood every day. During this process, they cleanse the blood, get rid of toxins and waste through urine, and maintain fluid balance in the body. The kidneys also produce several important hormones and enzymes, such as vitamin D – an important hormone for strong bones, and renin – an enzyme which helps to control blood pressure.
Kidney diseases happen when they fail to perform one or more of their important tasks, due to damages in the kidneys. The leading causes of such kidney damages are diabetes and high blood pressure. Several kidney conditions can happen, ranging from diabetic nephropathy (diabetic kidney disease), renovascular disease (kidney artery narrowing), nephrosclerosis (kidney hardening), glomerulonephritis (inflammation of kidney filters), to chronic kidney disease and kidney failure.
Unfortunately, the pervasiveness of kidney diseases in Singapore is worrying. According to statistics from the National Kidney Foundation (NKF), Singapore ranks first in the world for diabetes-induced kidney failures, and fourth in the world for prevalence of kidney failures, with 5.5 new cases diagnosed every day.
In this article, we will discuss in detail common kidney diseases among the elderly, and how diabetes and high blood pressures can lead to kidney diseases. We hope to raise awareness about kidney diseases, and bring attention to the devastating damages that diabetes and high blood pressure can cause to the kidneys, especially among elderlies who are at additional risk due to a phenomenon called the “aging kidneys”.
1. The risk factors of kidney diseases
1.1. Diabetes as the leading risk factor for kidney diseases
Diabetes is the leading risk factor for kidney diseases. This is especially true for diabetic patients who have uncorrected blood sugar due to unhealthy dietary habits and poor compliance to therapy. 40% of diabetes patients are estimated to develop diabetic kidney diseases at some point. In Singapore, according to data published by the National Kidney Foundation (NKF), an overwhelming ratio of 2 in 3 kidney failure cases are due to diabetes.
Scientists believe that chronic high blood sugar levels can wreak havoc on most organ systems and the blood vessels associated with them. The kidneys are highly susceptible, with each of them housing about a million filtering units – called nephrons – which are filled with tiny blood vessels responsible for cleansing the blood. The damages diabetes causes in the kidneys can lead to a number of serious kidney conditions, including:
- Diabetic kidney disease (DKD), also called diabetic nephropathy. This is one type of chronic kidney disease (to be distinguished with non-diabetic kidney disease)
- Glomerulonephritis, a group of kidney diseases involving inflammation of kidney tissues
- Kidney failure, also called end-stage renal disease.
Singapore has a high and rising incidence of diabetes. The number of diabetes cases is estimated to be as high as 1 million cases in 2050, which means kidney cases might be rising as a result if preventive measures are not taken. To learn more about diabetes and other devastating complications in addition to kidney diseases, check out our comprehensive guide to diabetes published earlier here.
1.2. High blood pressure ranks second in causes of kidney diseases
Chronic high blood pressure, or hypertension, is another top risk factor for kidney diseases. Reports state that it is the second leading cause of kidney failure in Singapore. Persistently high blood pressure may cause damages in the blood vessels, making them narrow and harden, restricting blood supply to various organs throughout the body. In the kidneys where millions of tiny blood vessels are hard at work to filter blood around the clock, damages in the kidney blood vessels will lead to kidney diseases.
One of the kidneys’ functions is to help regulate blood pressure. In a vicious cycle, less efficient kidneys are usually poorer in controlling blood pressure, aggravating hypertension and the risks of other cardiovascular diseases. In some patients, it is not clear if hypertension is the cause or symptom of kidney diseases. Scientists agree that the connection between high blood pressure and kidney diseases is strong, and both need to be treated and managed once diagnosed.
Of note, individuals with hypertension are found to be twice as likely to have diabetes, according to a study. In other words, the risk of developing kidney diseases in people with hypertension is compounded. It is therefore crucial to manage high blood pressure as early as possible, before this silent disease manifests into severe complications. Read our earlier article on hypertension and how to manage blood pressure at home and avoid complications here.
1.3. Aging and reduced kidney function
As we age, the kidneys become less efficient at filtering blood, due to a complex renal aging process that leads to structural and functional changes in the kidneys. Consequently, microscopic lesions start to accumulate until the patient develops a form of kidney disease, most commonly an acute kidney injury (AKI) which later develops into chronic kidney disease (CKD). People over the age of 60 are particularly at risk of kidney diseases.
Seniors are at higher risk for kidney diseases, because of comorbidity – or the existence of two or more conditions in the same individual, such as diabetes and high blood pressure. When you are over 60 years old with a medical history of diabetes and chronic high blood pressure, the risk becomes significant. The elderly are also at higher risk for other related conditions that are associated with kidney diseases, such as urinary incontinence, or urinary tract infection among older women. Read about urinary conditions and risk factors in elderlies in our article here.
When left untreated, kidney diseases can progress into serious consequences, even life-threatening. However, the good news is, in most cases, these conditions can be treated and kidney functions can be preserved with early detection. In the subsequent part of this article, we will go into details of common kidney diseases, including symptoms and risk factors, to equip you with the necessary knowledge to protect yourself and loved ones from the diseases and possible consequences.
2. Common kidney diseases in elderly
2.1. Chronic kidney disease
Chronic kidney disease (CKD) refers to the long-term progressive dysfunction of your kidneys. CKD is common with older age; however, it can affect anyone. Researchers found that CKD is more common in certain races, including Africans and South Asians. When CKD is not treated properly, it may eventually develop into kidney failure .
When CKD is caused by diabetes, it is referred to as diabetic kidney disease (DKD), medically known as diabetic nephropathy. Statistics in Singapore show that up to 40% of people who have diabetes develop DKD. However, the presence of both diabetes and CKD in one patient does not necessarily mean the person has diabetic kidney disease. Doctors often look at various factors to diagnose if a CKD case is diabetic.
Symptoms of CKD
The early stages of CKD do not present with any symptoms. In fact, most cases are possibly diagnosed after a blood or urine test. Initially meant for the presenting medical condition.
In serious stage when kidney damage persists, CKD patients may experience the following symptoms:
- Feeling tired
- Swelling of the ankles and feet
- Shortness of breath
- Loss of appetite and a general sense of being sick
- Blood in the urine (called hematuria)
Causes of CKD
Similar to most kidney disorders, the causes and risk factors of CKD are:
- High blood pressure, or hypertension
- Uncontrolled diabetes
- Dyslipidemia (i.e., high level of cholesterol or other types of fat in blood, such as in the cases of high LDL or low HDL or both)
- Glomerulonephritis (inflammation of the kidney filters)
- Infections of other parts of the kidneys
- Long-term use of certain drugs (e.g., lithium, non-steroidal anti-inflammatory drugs)
Diagnosis of CKD
The diagnosis of CKD is usually done with blood and urine tests, and in some cases imaging test. The doctor will look for measurements that indicate how well your kidneys work and if there are signs of kidney damages. Based on the results of your tests and a particular measurement called eGFR (estimated glomerular filtration rate), your doctor will stage your disease, which is important to determine the best therapeutic approach.
CKD is staged from 1 to 5. In stage 1 and 2, the kidneys are working fine but there are signs of kidney damage, more serious in Stage 2 than Stage 1. CKD Stage 3 and 4 indicate moderate to severe kidney damage. In Stage 5 CKD, also called end stage renal disease (ESRD) or kidney failure, the kidneys are almost or have started failing.
Treatments for CKD
There is no cure for CKD, but treatment is mainly focused on relieving symptoms and to stop progression of the disease. In early cases, treatments are: lifestyle changes – to help you stay as healthy as possible and medication to control associated problems such as high blood pressure and high cholesterol. In advanced cases, dialysis and kidney transplant might be recommended. Regular checkups are indispensable to monitor disease progression and administer timely intervention.
If an underlying cause can be identified, treatment will also include measures to manage and prevent exacerbation of the underlying condition, such as in the case of high blood pressure, diabetes, or dyslipidemia. As with all chronic diseases, lifestyle modifications to adopt a healthier way of living are important to manage CKD.
2.2. Kidney failure
Kidney failure, or end-stage renal disease (ESRD), describes the last stage of chronic kidney disease (CKD). However, this condition could also occur abruptly without a history of CKD. There are the two types of kidney failure:
Acute kidney failure (AKF)
Acute kidney failure (AKF), or acute kidney injury, develops within a few hours or days. This condition may occur because of physical trauma to the kidney or severe dehydration. Extremely high blood pressure and large kidney stones could also trigger AKF. Most patients recover their renal function after appropriate treatment, according to the Urology Care Foundation. Read more about causes, signs, symptoms and treatment of kidney stones in our separate article here.
Chronic kidney failure (CKF)
Unlike AFK, chronic kidney failure occurs over a long period of time. The damage accumulates progressively until the kidneys are unable to function.
Symptoms of kidney failure
Depending on the type of kidney failure (acute vs. chronic), the signs and symptoms vary greatly.
Here are some common symptoms to expect:
- Swelling of the feet and legs (known as edema)
- Numbness or tingling in the fingers or toes
- Lethargic or an overall tiredness and lack of energy
- Muscle pain
- Loss of sleep or insomnia
- Loss of appetite
When there is kidney failure due to chronic kidney diseases and the patient reaches the last stage of this disease (stage 5), waste and toxins are not filtered and excreted out of the body through urine, building up in the blood and circulated throughout the body. Patients as a result may experience:
- Nausea and vomiting
- Breathing difficulty or breathlessness (dyspnea)
- Ammonia breath, or breath that smells like urine.
- Soapy or foamy urine, signaling that the kidneys are not functioning and protein gets into urine.
- Failure to produce urine (anuria)
- Loss of consciousness
Causes and risk factors of kidney failure
Acute and chronic kidney failure have different causes and risk factors.
Common causes of acute kidney failure are:
- Low blood flow to the kidneys due to dehydration or obstruction
- Very high blood pressure
- Large kidney stones or other urinary tract obstruction
- Other diseases with systemic consequences such as heart or liver conditions
- Autoimmune diseases
Common causes of chronic kidney failure are:
- Uncontrolled diabetes
- High blood pressure
- Severe renal infections
- Polycystic kidney disease (more on that later)
Complications of kidney failure
When the kidneys fail to cleanse blood, it can cause systemic damage to other organs throughout the body. Possible complications of kidney failure include:
- Heart disease: this is the most common cause of death among kidney patients who are on dialysis.
- High blood pressure: hypertension can cause kidney diseases and kidney failure. When kidneys fail, it can exacerbate hypertension, causing further systemic issues in the body.
- Anemia: one of the functions of the kidney is to help the body produce red blood cells. When the kidneys fail, the body does not make enough healthy red blood cells, causing dizziness, weakness, lethargic and even heart diseases.
- Bone loss: kidneys help produce vitamin D and other important substances to maintain strong bones. When the kidneys do not function well, bone tissues are not adequately replaced, resulting in bone loss.
- Buildup of fluid: when this happens in the lung or heart, it can be life threatening.
Treatment of kidney failure
Treatment for kidney failure often includes the following options:
Dialysis refers to artificially filtering your blood with the help of a dialysis machine. A common type of dialysis is peritoneal dialysis, where a lining gets inserted into your abdomen to filter blood.
We should note that dialysis is not a permanent treatment for kidney failure. It only helps with preventing complications until a solution becomes available.
Kidney transplant is often recommended for kidney patients who lose more than 80% of their renal function. The procedure involves waiting for a compatible kidney from a donor. Once the transplant is completed, immunosuppressive drugs are often prescribed to help the body cope with the new organ.
2.3. Other common diseases of the kidneys
2.3.1. Renal hypertension
Renal hypertension, or renovascular disease, describes a high blood pressure caused by the narrowing of arteries carrying blood to the kidneys, known as renal arteries. When this happens, the kidneys do not receive enough blood due to obstruction, they start releasing a hormone known as angiotensin II to increase blood supply to the kidneys. Over time, this can cause increases in systemic blood pressure, or overall hypertension, which in turn can lead to other cardiovascular diseases.
Similar to high blood pressure, renal hypertension does not show any symptoms until it is serious, in which case it may cause headache, nausea, vomiting, confusion, and bleeding in the nose or in urine. It can be treated with medications used for high blood pressure. In some cases, the renal arteries need to be widened to facilitate blood flow to the kidneys, via procedures known as angioplasty, stenting or surgery.
2.3.2. Hypertensive nephrosclerosis
High blood pressure gradually wreaks havoc on the small arteries inside your kidneys, leading to irreversible damage. When the renal tissue starts to harden, we call that nephrosclerosis.
Hypertensive nephrosclerosis may develop into chronic kidney disease eventually. Often, the symptoms are similar to CKD, and only obvious in the serious stage, including nausea, vomiting, loss of appetite and feeling sick, headache and confusion.
Treatment for hypertensive nephrosclerosis aims to keep blood pressure under control and prevents deterioration of kidney functions.
Glomerulonephritis describes the inflammation of the glomeruli, which are the filtering units in the kidney.
This condition could either be acute or chronic. The severity of symptoms also varies from one individual to another. Typically, individuals who develop glomerulonephritis have the following risk factors:
- High blood pressure
- Diabetes or diabetic kidney disease
- Infections such as viral infection or recurrent, untreated strep throat infections
- Autoimmune diseases such as Lupus
Glomerulonephritis manifests with the presence of protein or blood in the urine. Observable symptoms include soapy urine (sign of protein in urine), pinkish urine (sign of blood in urine), swelling of hands and feet or face (sign of fluid retention). High blood pressure can be a cause and also a symptom of glomerulonephritis.
Treatment for glomerulonephritis focuses on addressing the underlying causes and preserving kidney function.
2.3.4. Polycystic Kidney Disease
Polycystic kidney disease is characterized by clusters of fluid-filled sacs (i.e., cysts) that develop all around the kidneys, compromising their ability to filter blood. Over time, the kidneys become larger in size, leading to kidney failure.
Researchers managed to identify some conditions that increase the risk of PKD, which include:
- PKD1 gene – polycystic kidney is known as a genetic disease
- Having large kidneys
- Multiple episodes of blood in the urine
- High blood pressure
- Gender (males)
- Ethnicity (African Americans)
Symptoms of polycystic kidney disease include blood in urine, headache, nausea, back pain, enlarged abdomen. Sometimes it leads to other conditions which manifest as symptoms, such as kidney stone, kidney failures or high blood pressure.
As a genetic disease, polycystic kidney disease cannot be cured. Treatment aims to remove the cyst and slow down the rate of new cysts forming in the kidney. For polycystic kidney disease that has progressed to kidney failure, dialysis and kidney transplants are often necessary. Other treatments such as hormonal therapy, blood pressure medication, and antibiotics may also be necessary depending on individual cases.
3. Takeaway message
Singapore has an unusual prevalence of kidney diseases. The top 2 causes of kidney diseases are 2 other common chronic conditions – diabetes and high blood pressure. Elderly adults are particularly at risk, due to their susceptibility to diabetes and high blood pressure, compounded with the aging factor, and comorbidities.
If you are at risk of kidney disease (e.g. old age, diabetic, hypertensive), it is advisable to go for regular screening for kidney disease, to ensure earliest detection possible. Diabetes patients at any age should screen for kidney diseases regularly, starting from the point of diagnosis. Though kidney diseases could progress to the devastating stage of kidney failure, it is treatable if detected and intervened early. However, if left untreated, there is a chance for various kidney diseases to progress into kidney failure, which requires costly regular treatment for a lifetime and have significant impact on the patient’s quality of life.
Like other chronic illnesses, management of kidney diseases in most cases requires life-long commitment. In addition to monitoring blood pressure and blood sugar, it is important to maintain an overall healthy lifestyle. A balanced diet with low intake of salt and sugar helps to keep diabetes and hypertension in check. So does regular exercise, maintaining healthy body weight and quitting smoking. A healthy body helps to maintain healthy kidneys, and healthy kidneys are crucial in keeping the overall body healthy.