Chronic Kidney Disease (CKD) Has Become a Public Health Issue Affecting People of All Ages

Kidney Disease: A Public Health Approach

Kidney Disease: A Public Health Approach

By: Shannon Mikrut

Chronic kidney disease (CKD) has become a public health issue affecting people of all ages all over the world. According to the National Institute of Health (NIH), (2012) one in ten American adults have some level of CKD. CKD is the loss of kidney functioning over time and has been broken down into a five stage progressive classification system that is used internationally (Stenvinkel, 2010). There are no cures for CKD and patients are unable to gain back any kidney functioning that has been lost. CKD is largely under diagnosed due to being asymptomatic in its early stages. If advanced, the disease can lead to complete kidney failure, also referred to as end stage renal disease (ESRD), and eventually death. It has been estimated that the total worldwide cost for treating patients with (ESRD) exceeds one trillion US dollars (Stenvinkel, 2010). Rates of CKD are increasing and measures need to be taken from a global approach to address this issue.

CKD affects people of all ages all over the world. CKD is defined by the Kidney Disease Quality Outcome Initiative, a global non-profit organization that focused on improving care outcomes for CKD patients, as “kidney damage or glomerular filtration rate (GFR) <60 mL/min/1.73 m2 for 3 months or more, irrespective of cause” (Levey, Eckhardt, Tsukamoto, Levin, Coresch, Rossert, DeZeeuw, Hostetter, Lamiere, & Eknoyan, 2005, p. 2089). The glomerular filtration rate is a measurement used to test how well the kidneys are functioning by testing how much creatinine is present in the blood. Creatinine is produced by the muscles in the body and builds up in the blood when the kidneys are not functioning at normal levels. The GFR estimates how much blood passes through the glomeruli, tiny filters in the kidneys, each minute (NIH, 2012). GFR naturally decreases with age so gender, age, weight, height, and race are also part of the GFR formula. Rates of 90-120 mL/min/1.73 m2 are considered normal while rates of <15 mL/min/1.73 m2 signify kidney failure and require immediate medical attention (NIH, 2012). CKD can lead to kidney failure, complications from decreased kidney functioning and increased risk of cardiovascular disease (Levey, Atkins, Coresh, Cohen, Collins, Eckardt, Nahas, Jaber, Jadoul, Levin, Powe, Rossert, Wheeler, Lameire, & Eknoyan, 2007). CKD appears to be an independent risk factor for cardiovascular disease and CKD patients are more likely to die from cardiovascular disease than from kidney failure (Levey et al., 2005, Leavey et al., 2007). Cardiovascular disease accounts for an estimated 50% of deaths of patients on dialysis (Zoungas, Lui, Kerr, Teede,, McNeil, McGrath, & Polkinghorne, 2011).

Twenty six million American adults have some level of CKD (Wetmore, Palsson, Belmont, Sigurdsson, Franzson, & Indridason).The prevalence of chronic kidney disease (CKD) has reached proportions with 10–13% of the populations in Taiwan, Iran, Japan, China, Canada, India and the United States (Stenvinkel, 2010). CKD in the United States has increased from 10.0% in 1988-1994 to 13.1% during 1999-2004 (Stenvinkel, 2010). Taiwan has had an even greater increase, with prevalence in 1996 at 2.0% and in 2003 rates had increased to 9.3% (Stenvinkel, 2010). CKD is more widespread among people of African American, Hispanic, and Native American descent due to higher rates of diabetes and hypertension in these populations (NIH, 2012). Indigenous peoples also have higher rates of CKD among both children and adults (White, Wong, Sureshkumur, & Singh, 2010). CKD can affect people of any age but prevalence is increasing in ageing adults (Ng & Anpalahan, 2011). Patients over the age of 75 years comprise nearly 25% of patients receiving dialysis in the United States and Australia (Ng & Anpalahan, 2011).

Diabetes and hypertension are the leading causes of CKD worldwide (NIH, 2012). Diabetes is a disease that affects the body from using glucose. Unused glucose in the blood can damage the nephrons in the kidneys. Forty four percent of patients on dialysis have kidney failure caused by diabetes (NIH, 2012). “Due to an increased amount of people being diagnosed with diabetes and hypertension and the estimation that the percentage of the population above 60 years of age will double from 11% in 2007 to 22% in 2050, an increase in the prevalence of CKD can be expected in years to come (Stenvinkel, 2010). CKD can be inherited and is more common in families that have a history of kidney failure (NIH, 2012). CKD can result from a variety of other health conditions. The other common causes of CKD are Glomerulonephritis, a group of diseases that cause inflammation and damage to the kidney's filtering units, lupus, obesity, old age, kidney obstructions, repeated urinary tract infections and malformations of the kidneys (NIH, 2012, Stenvinkel, 2010). Glomerulomegaly, the abnormal enlargement of glomeruli, has been frequently observed in Indigenous populations of Aboriginal people, Native Americans, and African Americans (NIH, 2012, White et al., 2010). Lower socioeconomic conditions, ethnic minority status, diet, social exclusion, prenatal alcohol exposure, stress factors, and lack of access to medical care have been attributed to an increased risk of CKD (Levey et al., 2005, White et al., 2010).

There currently is no cure for CKD. However, there are some steps that can be taken to reduce the risk of developing or the progression of CKD. Eating a healthy diet that is low in sodium can help keep the blood pressure low. Not smoking, avoiding pain medications which are hard on the kidneys, controlling blood pressure, proper management of diabetes, and managing stress are measures that can be taken to help decrease the risk of developing CKD (NKUDIC, 2012). Globally, CKD is under diagnosed (Bonner, Wellard, & Caltabiano, 2010). The disease is under diagnosed mainly due to CKD being asymptomatic in nature; CKD is often not detected until its later stages (Stenvinkel, 2010). “Chronic kidney disease is frequently clinically silent in the early stages, resulting in most patients being detected shortly before, or with, the onset of symptomatic disease (O’Seaghdah et al., 2012, p. 271). Symptoms of CKD include having high blood pressure, swelling of the feet and hands, a decreased GFR, urinary abnormalities, muscle cramps, darkening of the skin, trouble concentrating, feeling tired, loss of appetite, having the need to urinate more often, nausea or vomiting, and feeling itchy or numb (The Kidneys and How They Work. National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC), 2012, White et al., 2010). Having a co morbidity may be an indicator that a CKD is present. High blood pressure can cause CKD, but CKD can also cause high blood pressure. It is very important for CKD patients to maintain a normal blood pressure. CKD is hard to detect due to patients not displaying symptoms until the later stages of the disease. This is why it is important now more than ever to encourage early diagnosis of CKD. CKD is not difficult to test for. Testing can be done by a primary care physician or a nephrologist, a kidney specialist.

There are a three commonly used tests to determine kidney functioning. The Glomerular Filtration Rate (GFR), as referred to previously, is a blood test that calculates the efficiency of the kidneys filtering wastes from the blood by testing the creatinine levels. A urine albumin test may also be used. When the kidneys are not functioning properly a blood protein called albumin is typically present in the urine (NIH, 2012). A urine sample can be tested to determine if albumin is present. The higher the concentration of albumin present, the more the kidneys are compromised. Checking for high blood pressure can also be used as it can be an indicator that the kidneys are not functioning at normal strength. Additional testing includes having a kidney biopsy, kidney imaging, and/or a Blood Urea Nitrogen test (NIH, 2012).

When an individual reaches a GFR of <15 mL/min/1.73 m2 it is often referred to as ESRD. ESRD is permanent total or near total kidney failure. In 2009, more than 871,000 Americans were treated for ESRD (NIH, 2012). CKD and ESRD are much more common in Indigenous than non-Indigenous people, and rates have been increasing (White et al., 2010). Kidney replacement therapy is needed at this stage and the two options for patients are dialysis and transplantation. Dialysis is used to help clean the blood and rid of wastes within the body. Since the kidneys are not able to do this on their own, dialysis acts as a form of life support. “Both in the US and worldwide, the prevalence of ESRD continues to rise, likely reflecting changing demographics (including an aging population with increasingly common co-morbid diseases, such as hypertension and diabetes mellitus) as well as improved survival among individuals with ESRD (Menzin et al., 2011, p. 840).”

There are two different types of dialysis, hemodialysis and peritoneal dialysis. Hemodialysis acts as an artificial kidney and cleans the blood of extra salt, extra water and wastes. In this process, blood is carried into the machine’s dialyzer where the blood is cleaned and returned to the body (NKUDIC, 2012). Dialysis is typically performed at a clinic, but medical advances have allowed for people to do dialysis in the comfort of their homes. During peritoneal dialysis a dialysis fluid is put into the abdomen and after a few hours the fluid is passed out through a catheter (NKUDIC, 2012). Dialysis helps to prolong the life of kidney patients by filtering the blood and bringing levels back to normal.

Transplantation is the other option for ESRD patients. In the United States, the organization, United Network of Organ Sharing (UNOS), maintains organ donation throughout the country (Schneider, 2011). Transplants can come from deceased organ donors or from a living donor that is willing to donate a kidney. In 2009, more than 16,000 kidney transplants procedures were performed in the United States (NIH, 2009). “Between 1980 and 2009, the prevalent rate for ESRD increased nearly 600 percent, from 290 to 1,738 cases per million” (NIH, 2012). Early identification of CKD may provide the best opportunity for patients to take preventative steps and receive treatment to slow renal function (O’Seaghdha et al., 2012). Affordable access to medical care and CKD awareness are interventions that need to be made a priority worldwide.

The kidneys are paired organs located on either side of the vertebrae in the upper lumbar and lower thoracic region of the abdomen (Silverthorn, Ober, Garrison, Silverthorn, & Johnson, 2010). They are part of the urinary system that also includes the ureters, urinary bladder, and urethra (Marieb, Wilhelm, & Mallatt, 2012). The main function of the kidneys is to produce urine. Urine flows from the kidneys through the urinary system and is excreted outside of the body. It is a liquid substance made from water, solutes, and waste products brought to the kidney through the renal artery. (Krieger, 2009). The renal artery brings this oxygenated blood containing waste products into the kidney, which feeds into five smaller arteries located in the renal pelvis called segmental arteries (Marieb et al., 2012). These segmental arteries branch into smaller and smaller arterioles and eventually branch into the microscopic nephrons. According to Marieb et al. (2012) “The main structural and functional unit of the kidney is the nephron” (p. 712). Silverthorn, D, Ober, Garrison, Silverthorn, & Johnson states that there are over one million of these tiny nephrons located on each kidney (2010). At the nephron’s center is the glomerular capsule, which contains the glomerular capillaries (Marieb et al., 2012). Leading to the glomerular capillaries is the afferent arteriole, which brings the blood into the glomerular capsule and the glomerular capillaries (Marieb et al., 2012). Blood flows out of the glomerular capillaries through the efferent arteriole, which follows the proximal convoluted tubule (Marieb et al., 2012). Urine that is made in the glomerular capsule is carried out by the proximal convoluted tubule (Marieb et al., 2012). This tubule is located in the renal cortex of the kidney but crosses through the renal medulla in a ‘U’ shape called the nephron loop (Marieb et al., 2012). This loop then crosses out of the renal medulla and into the renal cortex and because the distal convoluted tube which carries urine into the collection duct to be taken to the ureters (Marieb et al., 2012).

As the functional unit of the kidney, the nephron is responsible for three interconnected processes: filtration, reabsorption, and secretion (Silverthorn et al., 2010). Filtration is the process where fluid in the blood drains from the capillaries into the interior cavity of the glomerular capsule (Silverthorn et al., 2010). The filtrate that passes into the interior cavity of the glomerular capsule is destined to be excreted from the body through the convoluted tubules and the ureters (Silverthorn et al., 2010). Some of this filtrate that is destined for excretion is reabsorbed back into the efferent arteriole that is following the proximal convoluted tubule, the nephron loop, the distal convoluted tubule and the collecting duct (Silverthorn et al., 2010).

When the kidneys are not functioning properly the GFR decreases. “The volume of fluid that filters into the Bowman’s capsule per unit time is the GFR” (Silverthorn et al., 2010, p. 19). GFR is influenced by net filtration pressure, which is comprised of renal blood flow and blood pressure, and the filtration coefficient (Silverthorn et al., 2010).The filtration coefficient is comprised of the surface area of the glomerular capillaries available for filtration and permeability of the capillary-Bowman’s capsule interface (Silverthorn et al., 2010). When the GFR decreases this signifies that the kidneys are not functioning at normal levels. When the kidneys are not functioning properly creatinine and a blood protein called albumin is typically present in the urine. Most kidney diseases attack the nephrons (NKUDIC, 2012). When the nephrons are damaged they are unable to properly filter and keep chemicals within the body balanced. Significant nephron damage can ultimately lead to death. There is no way to gain nephron functioning once it has been lost. Damage can also occur to the vessels in glomeruli which leads to decreased kidney functioning (NKUDIC, 2012). CKD comes in many forms and can be the result of a genetic abnormality, an injury, another illness or an autoimmune disease. A common inherited kidney disease is Polycystic kidney disease, in which kidney tissues are replaced with fluid filled cysts (NKUDIC, 2012). A severe loss of blood, poisons, and some drugs can disrupt kidney functioning (NKUDIC, 2012).

CKD has been broken down into a five stage classification system that is used internationally (Stenvinkel, 2010). The five stages reflect the glomerular filtration rate (GFR) as well as evidence of kidney damage. Each stage is progressively worse with decreasing levels of kidney functioning. Stage 1 is the first stage of CKD and indicates slightly diminished kidney functioning. The GFR of stage 1 is ≥90 mL/min/1.73 m2 (Stenvinkel 2010). Stage 2 is considered a mild reduction in kidney functioning and has a GFR of 60–89 mL/min/1.73 m2 (Stenvinkel, 2010). Stage 3 is described as moderate reduction of kidney functioning. To be considered stage 3 the GFR limit is 30–59 mL/min/1.73 m2 (Stenvinkel, 2010). In the final two stages of CKD the kidneys are increasingly compromised and it is not until these later stages that most patients are identified (NKUDIC, 2012). In the last Stage 4’s GFR is 15–29 mL/min/1.73 m2 and is referred to as severe reduction. Stage 5 CKD indicates kidney failure and has a GFR of <15 mL/min/1.73 m (Stenvinkel). At stage 5 the kidneys are no longer able to remove waste and fluid from the body and medical treatment is necessary for survival. Patients with Stage 5 CKD are treated with kidney replacement therapy, dialysis and/or transplantation. Stage 5 is commonly referred to as ESRD.

The environment in which we live plays a significant role in the development and progression of CKD. A study completed by Nwankwo & Ummate (2006) found that lead, a heavy metal, has been established as playing a role in pathogenesis of hypertension and renal disease. High levels of lead in the bloodstream have been found to damage the proximal convoluted tubule which is responsible for reabsorption of solutes and water into the bloodstream (Nwankwo & Ummate, 2006, Marieb et al., 2012). Lead regulations started in the United States in the 1970’s to limit or prohibit lead in items such as gasoline, paint, salts and many industrial facilities that released lead into the atmosphere (Nwankwo & Ummate, 2006). Blood lead levels have decreased in the U.S. as a result of enforced regulations, but lead can still be found in some old houses, lead contaminated water, and old household products. Lead poisoning is still a concern in developing countries where strict lead regulations have not been pronounced (Nwankwo & Ummate, 2006). At this point, lead continues to be a public health problem (Nwankwo & Ummate, 2006). Exposure to cadmium, a toxic element found in the environment and commonly used in batteries, has been found to damage the proximal convoluted tubular cells and the renal cortex of the kidneys (Bernard, 2008). Construction and manufacture workers are at a higher risk of being exposed to cadmium. The Occupational Safety & Health Administration (OSHA) has set specific cadmium standards that protect workers from exposure; OSHA still estimates that 300,000 workers in the United States are exposed to cadmium in the workplace (Occupational Safety & Health Administration).