Introduction
Kidney disease refers to any condition that reduces kidney function over time. As the kidneys fail, they are no longer able to filter waste products and excess fluid from the blood. This can lead to a buildup of toxins and fluid in the body, which can cause symptoms like fatigue, shortness of breath, and itching (National Kidney Foundation, 2022).
Catching kidney disease early is critical because early treatment can help prevent or delay complete kidney failure. According to the National Kidney Foundation (2022), if kidney disease is detected early, steps can be taken to help preserve remaining kidney function and prepare for dialysis or transplantation if needed. Public awareness campaigns that educate people on kidney disease risk factors and the importance of early testing are key to improving early detection rates.
Blood and Urine Tests
Blood tests are one of the most effective ways to check for kidney disease. Doctors can use blood tests to measure levels of different substances that provide information on how well the kidneys are functioning. Some important blood tests include:
Glomerular filtration rate (GFR) is one of the best measures of kidney function. GFR is a measurement of how much blood passes through the kidneys’ filtering units called glomeruli each minute. A GFR below 60 for 3 months or more often indicates chronic kidney disease. GFR is calculated from a blood test for creatinine, a waste product in the blood (Healthdirect).
Creatinine is a waste product from normal muscle function that is filtered by the kidneys. High levels of creatinine in the blood indicate decreased kidney function (Bodyvie).
Albuminuria refers to the presence of the protein albumin in urine. Normal urine contains little to no albumin. Increased albumin in urine is an early sign of kidney damage (Harley Health Centre).
Blood Pressure
High blood pressure, or hypertension, is a major risk factor for developing chronic kidney disease and kidney failure. According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), high blood pressure can damage the small blood vessels in the kidneys over time https://www.niddk.nih.gov/health-information/professionals/diabetes-discoveries-practice/high-blood-pressure-kidney-disease. When the blood vessels are damaged, the kidneys cannot properly filter waste from the blood. This causes waste to build up in the body and the kidneys to not function properly.
The kidney filters over 200 quarts of blood per day. When blood pressure is high, the extra force damages the delicate blood vessels and filters in the kidneys. According to the Kidney Foundation of Canada, nearly half of all Canadians with high blood pressure will develop kidney disease https://kidney.ca/Kidney-Health/Newly-Diagnosed/Risk-Factors/High-Blood-Pressure-Kidney-Disease. Controlling high blood pressure is crucial to protect the kidneys from further damage.
Glomerular Filtration Rate
The best indicator of kidney disease is the glomerular filtration rate (GFR), which measures how efficiently the kidneys are filtering blood. The GFR is considered the “gold standard” for assessing kidney function [1].
As the National Kidney Foundation explains, “The universally accepted measure of kidney function is the Glomerular Filtration Rate (GFR).” A normal GFR falls between 90-120 mL/min, indicating healthy kidney function. As kidney disease progresses, the GFR declines. A GFR below 60 mL/min signifies chronic kidney disease [2].
Doctors can estimate GFR from blood tests measuring creatinine levels. Creatinine is a waste product filtered out by the kidneys, so its levels in the blood indicate how well the kidneys are working. GFR estimates kidney function more accurately than creatinine alone [3].
Protein in Urine
One of the most important indicators of kidney disease is proteinuria, or protein in the urine. Healthy kidneys should only filter tiny amounts of protein into the urine, usually less than 150 mg per day. Proteinuria signals kidney damage, as damaged kidneys allow an excessive amount of protein to pass into the urine.
Research shows a strong link between proteinuria, progression of kidney disease, and chronic kidney disease. According to a 2022 study published in Current Medical Research and Opinion, “Proteinuria is not only a marker of kidney damage, but may also play a pathophysiological role in the progression of kidney disease.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8718931/
Proteinuria may be an early sign of kidney damage, even before other symptoms appear. Testing urine for excess protein can help diagnose kidney disease at an early stage. Persistent proteinuria indicates ongoing kidney damage and is a risk factor for progression to end-stage kidney failure.
Anemia
Anemia tends to develop in about 12% of patients with Chronic Kidney disease (CKD). Progressing stages of CKD tend to elevate the risk of developing anemia [1]. Anemia is a condition that develops when your blood lacks enough healthy red blood cells or hemoglobin. Hemoglobin is the main part of red blood cells and binds oxygen. If you have too few or abnormal red blood cells, or your hemoglobin is too low, the cells in your body will not get enough oxygen.
As kidney disease progresses and the kidneys become less able to produce erythropoietin (EPO), a hormone that stimulates bone marrow to produce red blood cells, anemia is more likely to develop. Anemia may cause fatigue, weakness, dizziness, and other symptoms. Severe anemia can damage the heart and aggravate heart disease. At first, the kidneys compensate for a declining EPO production by producing even more EPO. But eventually, they cannot keep up and the production of EPO declines.
Bone Health
Chronic kidney disease can negatively impact bone health and bone mineral density. According to research from UCLA, ethnic differences exist in bone health among children with chronic kidney disease, indicating the disease affects certain populations more severely when it comes to bone issues (UCLA, 2022). Since advanced kidney disease affects bone metabolism through CKD mineral and bone disease, key factors like calcium, phosphate, parathyroid hormone, and vitamin D play complex roles in bone health for those with chronic kidney problems (Lin, 2023). Overall, chronic kidney disease can lead to weakened bones and increased fracture risk over time due to imbalances in bone mineral density.
Fluid Retention
One of the biggest indicators of kidney disease is fluid retention, which can lead to swelling (edema) in the legs, ankles, and around the eyes. As the kidneys fail, they are unable to efficiently remove extra fluid from the body. This causes sodium and fluids to build up in the blood, resulting in water retention that is noticeable as swelling.
According to the Texas Kidney Institute, “Kidney disease can cause fluid retention, which can lead to swelling (edema)” (source). Swelling is often first noticeable in the ankles and legs, as fluid pools in the lower extremities when the kidneys cannot adequately remove excess fluid. Puffiness around the eyes and facial swelling may also occur as fluid accumulates in the tissues.
Fluid retention tends to get progressively worse as kidney disease advances. Even small amounts of swelling can indicate impaired kidney function and the inability to filter wastes and fluid properly. Monitoring for edema and rapid weight gain from fluid retention can help diagnose kidney problems early.
Itching
Itching is a common symptom of kidney disease due to mineral and hormone imbalances that can occur as kidney function declines. According to the FDA, chronic kidney disease patients often experience severe itching due to buildup of waste products in the blood (Reuters). As kidneys fail, levels of calcium, phosphorus, and parathyroid hormone become abnormal, which can irritate skin and nerves causing itching (KidneyCoach). Doctors state itching is one of the key symptoms of kidney disease, as waste buildup and hormonal changes affect the skin (Yahoo).
Conclusion
In summary, some of the biggest indicators of kidney disease include elevated creatinine and urea levels in blood tests, high blood pressure, decreased glomerular filtration rate, proteinuria, anemia, bone disease, fluid retention, and persistent itching. The markers discussed in this article can detect kidney damage early on, sometimes well before symptoms appear. That’s why regular screening is crucial, especially for those at high risk like people with diabetes or hypertension. The sooner kidney disease is caught, the better the chances of slowing its progression. If you notice any of the major warning signs, talk to your doctor right away about getting simple blood and urine tests. With early detection and proper management, kidney damage can be minimized.
