What Causes Kidney Damage?

Each kidney contains about a million nephrons or filtering units. Each nephron has two parts: the glomerulus and a tubule. The glomerulus filters the blood, and the tubule removes waste and returns necessary substances into the bloodstream. The kidneys also produce several hormones, including renin, which contributes to maintaining blood pressure, electrolyte balance, and vascular resistance; kallikreins, which contribute to vasorelaxation; erythropoietin, which is essential for red blood cell formation in the bone marrow; and an active form of vitamin D that is essential for regulating calcium.

The primary causes of CKD are diabetes and high blood pressure. Diabetes causes high blood sugar, which can damage the kidney's filters. In time, the kidneys can become so damaged that they can no longer filter waste and remove fluid from the body. High blood pressure can damage the blood vessels leading to the kidneys, which can cause them not to work as well. Extra fluid accumulating in the body can raise the blood pressure even more. Other less common causes of kidney disease include polycystic kidney disease, toxins, lupus, and some rare genetic conditions.

Symptoms of CKD often do not appear until the later stages of the disease, and they are often non-specific, which means they can be attributed to other conditions. These symptoms may include urinating more or less, swelling in the feet and ankles, fatigue, weakness, sleep problems, nausea, vomiting, dry itchy skin, and high blood pressure.

Kidney disease generally does not produce symptoms in the early stages because the body is usually able to cope with a significant reduction in kidney function until it cannot any longer. Because of this, it is important to remember that you cannot rely on symptoms alone to determine if you have CKD. Routine health screenings are essential as CKD can be identified early with routine lab work.

Factors that can increase the risk of CKD include high blood pressure, diabetes, cardiovascular disease, and abnormal kidney structure. Several lifestyle factors also contribute to CKD risk, including smoking, obesity, and frequent use of medications that can damage the kidneys. CKD is also more common in those who are Black, Native American, or Asian American, have a family history of kidney disease, or are of an older age.

Because kidney disease typically has no symptoms in the early stages, getting regular checkups and screenings is critical for early detection. Doctors may order routine lab tests that can assess kidney function. One such test is GFR or glomerular filtration rate, which measures how much blood your kidneys filter in one minute. They may also do an estimated GFR, which measures waste products in the blood. Another blood test that measures kidney function is a creatinine test. Creatinine is a waste product from the normal breakdown of muscles in the body. The kidneys usually remove creatinine from the blood, but levels will rise if they are not working correctly. If your doctor suspects CKD, they may ask for urine tests to check for albumin. Albumin is a protein in the blood; healthy kidneys do not let protein into the urine. Albumin in the urine suggests a problem with the kidneys.

High blood sugar can damage blood vessels and nephrons, so the kidneys will not function as well as they should. The kidneys have to work harder, which can eventually lead to damage. Controlling high blood sugar levels is paramount to controlling type 2 diabetes and all of its complications, including chronic kidney disease.

High blood pressure can narrow or constrict the blood vessels all over the body, reducing blood flow. If this occurs in the kidneys, it prevents them from working correctly. When this happens, extra fluid builds up, increasing blood pressure even more. Blood pressure management is crucial to maintaining kidney health.

Genetic and autoimmune factors can also influence kidney health. For example, polycystic kidney disease is a genetic disorder in which cysts filled with fluid grow in the kidneys, enlarging them. It reduces kidney function and may lead to kidney failure. Autoimmune diseases, like lupus, can attack the kidneys, which can lead to kidney failure. There are also some genetic variants that are linked to kidney disease.

Signs of advanced or end-stage renal disease include fluid around the heart or lung, confusion, seizures, persistent nausea and vomiting, and malnutrition. Fluid overload does not respond to diuretics, and high blood pressure does not respond well to medications. There may be several metabolic imbalances, too, including high potassium and phosphorus and low or high calcium. During this stage, urgent medical attention is required.

There are multiple approaches to treating CKD. Many people with CKD take medication to lower blood pressure, lower cholesterol, and manage blood sugar. Lifestyle adjustments are also recommended, like exercising, getting enough sleep, and quitting smoking. Diets for kidney disease should prioritize fresh food and cooking from scratch instead of eating processed food or going out to eat. They must also carefully monitor how much sodium, phosphorus, and protein they eat. In later stages, dialysis or kidney transplantation may be necessary.

People living with CKD should work with a dietician to develop a meal plan to help them get to and maintain a healthy weight and learn about what food they should and should not eat. They should see their doctors regularly and take the necessary steps to keep other conditions that can worsen CKD under control, like high blood pressure and diabetes. Mental and emotional support are also essential. People with chronic illnesses commonly suffer from a range of issues, including insecurity, anxiety, depression, and fear. Seeking the right support can help manage these problems and give people with CKD maintain a better quality of life.

Managing risk factors can help prevent the development or progression of CKD. Establishing good blood sugar control and managing blood pressure and cholesterol levels is crucial to help prevent kidney damage. Lifestyle and dietary changes are also important. Eating a balanced diet and exercising can help maintain a healthy weight.

There are many future treatments for CKD being studied. The FDA approved a new medication in 2021 that can reduce the risk of kidney failure and kidney function decline in adults with CKD who are at risk of disease progression. Research is ongoing, so continued awareness and education about advances in this field are critical.

According to the CDC, as many as nine in 10 of people with CKD do not know that they have it. Symptoms may not appear until the disease has progressed, so early detection and management are important. Routine lab work can uncover a problem, so it is essential to get regular checkups, especially if you have high blood pressure or diabetes.