Chronic Kidney Disease: Causes, Symptoms and Treatment
Chronic kidney disease is a progressive, chronic, and silent disorder caused by alterations in renal structure or function. To be defined as such, this renal impairment must be persistent for a period of more than 3 months and is characterized by a gradual, and generally irreversible, decrease in the glomerular filtration capacity of the kidney.
Its causes are multiple, and the most common include diabetes mellitus, high blood pressure, and a prolonged use of certain medications. Any factor that produces sustained structural or functional renal damage can cause a decrease in its function.
That’s why knowing its associated factors and clinical symptoms is essential for diagnosis, as well as to prevent progression and improve long-term prognosis.
Causes of chronic kidney disease
Chronic kidney disease can have a variety of causes, and is usually related to a combination of several factors.
Even so, worldwide, the most frequent cause of chronic kidney disease is as a result of diabetes mellitus. This is followed by arterial hypertension (and vascular disorders) and glomerular diseases.
To a lesser extent, it’s also caused by tubulointerstitial disorders, immune diseases, and polycystic kidney disease. When the cause can’t be determined and the person is hypertensive, it’s usually attributed to arterial hypertension.
Other conditions such as chronic urinary obstruction, recurrent urinary infections, prolonged use of certain medications (such as non-steroidal anti-inflammatory drugs) and some hereditary diseases can contribute to the development of it.
Effects of diabetes on the kidney
Diabetes (both type 1 and type 2) is the leading cause of chronic kidney disease. This is because the high level of sugar in the blood produces structural damage to the blood vessels, affecting those that are part of the kidney filtration barrier and leading to a decrease in kidney function.
High blood pressure also causes kidney damage
High and sustained blood pressure causes an excessive increase in pressure within the kidney’s blood vessels, which affects the glomerular filtration barrier structures and, in the long term, leads to chronic kidney disease.
Symptoms of chronic kidney disease
Chronic kidney disease is usually asymptomatic in its early stages and symptoms develop as it progresses.
The first symptoms are usually general and include fatigue, weakness, loss of appetite (and weight loss secondary to decreased intake), nausea, vomiting, swelling in the extremities, difficulty concentrating, chronic back pain, headache, and changes in the frequency and volume of urination.
Fatigue and weakness are usually the most frequent and obvious symptoms because they affect the ability to carry out daily activities.
When the disease progresses, complications such as anemia, arterial hypertension, and bone disease are associated.
Effects of decreased kidney function
In chronic kidney disease, as glomerular filtration impairment progresses, changes in the frequency and volume of urination occur. In general, there’s an increase in the frequency of urination, especially at night (nocturia), which progresses to a decrease in urine production.
As the kidney progressively loses its ability to eliminate excess fluids, fluid retention occurs, leading to swelling of the extremities and even the face and abdomen. The increase in volume within the vessels produces an increase in pressure, which causes or aggravates arterial hypertension.
The loss of renal function also produces a decrease in the production of erythropoietin. This hormone participates in the production of red blood cells, which can lead to a decrease in hemoglobin levels in the blood with consequent anemia.
Production of the active metabolite of vitamin D is also affected, which compromises calcium metabolism and can lead to bone disorders such as osteoporosis or renal bone disease.
Diagnosis of chronic kidney disease
For the diagnosis of chronic kidney disease, the combination of clinical criteria, evaluation of renal function, and findings in complementary laboratories is required.
Clinical criteria for diagnosis
According to the National Kidney Foundation, chronic kidney disease by definition is the presence of changes in kidney structure or function that occur over a period of more than 3 months. So there must be one of the following sustained conditions in that period of time:
- Decreased glomerular filtration rate below 60 ml/min/1.73 m2. The elevation of serum creatinine is an indirect indicator that there’s a decrease in the glomerular filtration rate, but there may be deterioration of the same with creatinine values within the normal range.
- Demonstration of structural or functional alterations, although the glomerular filtration rate is normal. These include the following:
- Albuminuria greater than 30 mg/day
- Other disturbances of the urinary sediment (such as loss of blood in the urine or haematuria)
- Electrolytic disturbances due to tubular defects
- Imaging-detected kidney conditions (for example, polycystic kidneys, hydronephrosis, or horseshoe kidney)
- Kidney transplant
Additionally, chronic kidney disease can be divided into 5 stages, according to Fresenius Kidney Care, based on the degree of decreased glomerular filtration rate. The stages of CKD range from stage 1, with normal or near-normal kidney function, to stage 5, known as end-stage chronic kidney disease, when kidney function is severely impaired and dialysis or a kidney transplant is needed to keep life.
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The following may be used in the evaluation of renal function:
- Serum creatinine measurement: Creatinine is a waste product produced by the muscles and eliminated primarily through the kidneys. Elevated serum creatinine levels suggest decreased kidney function.
- Glomerular filtration rate estimation: Kidney filtration rate can be measured indirectly with serum creatinine value, age, gender, and race by using formulas. The result is expressed in milliliters per minute and is used to classify chronic kidney disease into different stages according to the severity of the decline in kidney function.
- Urinalysis: With the determination of protein in the urine (called proteinuria) which is an indicator of kidney damage and the main indicator of its progression. The presence of blood in the urine (hematuria) is also detected.
- Imaging studies: Mainly renal ultrasound that generates images of the kidneys through sound waves, which allows doctors to evaluate the size, structure, and presence of structural abnormalities in the kidneys. In cases where more detailed images are required, computed tomography or magnetic resonance imaging is used.
- Kidney biopsy: Used only in selective cases where a thorough evaluation of kidney disease is required. It consists of taking a small sample of kidney tissue for histopathological analysis under a microscope.
Treatment of chronic kidney disease
Chronic kidney disease is an irreversible disorder, so its treatment is based on controlling the underlying causes, preventing disease progression, and managing complications.
The fundamental thing in controlling it is to maintain adequate control of blood pressure and glucose levels in people with high blood pressure and diabetes. Additionally, these people may benefit from medications such as angiotensin-converting enzyme inhibitors to control proteinuria.
On the other hand, the intake of salt and fluids should be restricted, regular physical exercise should be promoted, and anemia and bone metabolism disorders should be treated. Sometimes it may be necessary to use iron supplements and hormones that stimulate the production of red blood cells to improve hemoglobin levels in the blood, as well as supplementation with vitamin D and calcium.
In end-stage chronic kidney disease, it’s necessary to resort to renal replacement therapy, which includes hemodialysis, peritoneal dialysis, or kidney transplantation. Hemodialysis and peritoneal dialysis filter and remove waste products and excess fluids from the kidney, replacing the kidney’s ability to filter substances, while kidney transplantation recovers kidney functions.
Renal replacement therapy is usually indicated when the glomerular filtration rate is below 10 ml/min/1.73 m2.
Chronic kidney disease requires a lot of medical attention
It’s important to note that the diagnosis of chronic kidney disease must be made by a specialist doctor who will evaluate the results of the tests. Based on the clinical history, they’ll determine the precise diagnosis and the appropriate treatment.
In addition, its management must be multidisciplinary and this includes the support of nutritionists, nurses and other health professionals, as well as family support. It’s important to follow medical instructions and perform regular medical follow-up to assess the progression of the disease.
- Alles, A., Fraga, A., García, R., Gómez, A., Greloni, G., Inserra, F., Mazziotta, D., Torres, Maria L., Villagra, A. (2010). Detección precoz de Enfermedad Renal Crónica. Acta Bioquímica Clínica Latinoamericana, 44(3), 377-384. http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0325-29572010000300010&lng=es&tlng=es
- Ávila, S., María, N. (2013). Enfermedad renal crónica: prevención y detección temprana en el primer nivel de atención. Med Int Mex 29, 148-153. https://www.medigraphic.com/cgi-bin/new/resumen.cgi?IDARTICULO=41436
- de Francisco, A. L. M., Otero, A. (2003). Epidemiología de la enfermedad renal crónica en España. Nefrología, 23, 6. https://www.revistanefrologia.com/es-epidemiologia-enfermedad-renal-cronica-espana-articulo-X021169950301652X
- Flores, J., Alvo, M., Borja, H., Morales, J., Vega, J., Zúñiga, C., Müller, H., Münzenmayer, J. (2009). Enfermedad renal crónica: Clasificación, identificación, manejo y complicaciones. Revista Médica de Chile, 137(1), 137-177 https://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0034-98872009000100026
- Fresenius Kidney Care (s.f.). Etapas de la enfermedad renal. Consultado el 19 de junio de 2023. https://www.freseniuskidneycare.com/es/kidney-disease/stages
- Gámez, J., Ana, M., Montell, H., Ruano, V., Alfonso, J., Puente, Z. (2013). Enfermedad renal crónica en el adulto mayor. Revista Médica Electrónica, 35(4), 306-318. http://scielo.sld.cu/scielo.php?script=sci_arttext&pid=S1684-18242013000400001&lng=es&tlng=es
- Poll, P., Jorge, A., Rueda, M., Nuris, M., Poll, R., Mancebo, V., Arias, M. (2017). Factores de riesgo asociados a la enfermedad renal crónica en adultos mayores. MEDISAN, 21(9), 2010-2017. http://scielo.sld.cu/scielo.php?script=sci_arttext&pid=S1029-30192017000900006&lng=es&tlng=es