There are blood and urine tests which are performed in few repetitions to confirm Chronic Kidney Disease.
For healthy persons above age of 60 years and persons having high blood pressure, and diabetes, it is a must to get a kidney function test done on yearly basis to detect kidney disease at an early stage. Since individuals suffering from diabetes and hypertension are more at risk for developing chronic kidney disease (CKD) and cardiovascular diseases, patients and their families should watch for physical symptoms of kidney disease like puffiness under eyes, swelling of foot, reduced urine output, etc.
A list of tests is provided below including reasons, as to how these tests are related to kidney functioning. The doctor may advise some or all of the tests as per medical condition of the patient.
Blood Pressure-High blood pressure is the second leading cause of kidney disease after diabetes. It damages the small blood vessels in the kidneys impairing kidney function. If blood pressure is high, targeted treatment will be required, which may include taking high blood pressure medications (ACE inhibitors), cutting down dietary salt intake, losing excess weight and following a regular exercise program in consultation with doctor and dietitian.
- Blood Sugar-Diabetes or blood sugar is the leading cause of kidney disease.
- Serum Creatinine-Creatinine is a waste product that forms when creatinine, which is found in the muscle, breaks down. Creatinine levels in the blood provides a fairly reliable measure of how well the kidney is functioning. If a person has a high blood creatinine level but a low urine creatinine level, it might be a sign that the glomerulus is not working efficiently. The best way to lower creatinine levels is to treat the underlying cause. There are also many diet and lifestyle changes that can help reduce creatinine.
- Serum Albumin: Albumin is a type of body protein made from the protein ingested each day. A low level of albumin in blood may be caused by not getting enough protein or calories from dietary intake. A low level of albumin may lead to health problems such as difficulty fighting off infections.
- Lipid Profile-Lipid profile tests the cholesterol level, triglyceride levels, etc in the blood stream. It is common knowledge that higher cholesterol and triglyceride levels may increase cardiovascular risk. When kidney is damaged, it is unable to metabolise lipids in the blood leading to dyslipidaemia (abnormal lipid in blood). Maintaining a simple balanced diet and avoiding dietary fat like ghee, butter, oil, deep fried food, animal protein (red meat) etc may keep at bay severe disease progression.
- Haemoglobin (Hb)– Kidney produces hormone erythropoietin which stimulates bone marrow to produce red blood cells. Red blood cells contain oxygen carrying protein, Haemoglobin (Hb) which carries oxygen from lungs to all parts of the body including brain. Low haemoglobin in body is known as anemia, a condition in which less oxygen is circulated in body resulting in tiredness, shortness of breath and low energy. If kidney is damaged or functioning partially, erythropoietin is not secreted leading to anemia. Individuals diagnosed with kidney disease may be required to take erythropoietin hormone injections (erythropoiesis stimulating agent-ESA) as per doctors’ advise. In patients suffering from Chronic Kidney Disease and undergoing dialysis, anemia is common but Hb levels below 7 must be immediately addressed by packed cells volume (PCV) transfusion. Although anaemia can happen to due to various reasons other than kidney disease, it is one of the tests done for checking kidney functioning and whether medication is required to treat the same.
- Hematocrit, TSAT, Serum Ferritin– These tests measure the iron deficiency status. Iron is a mineral which helps in producing red blood cells. If there is iron deficiency, ESA therapy may not work effectively. Ferritin injection may be given in case of iron deficiency to CKD patients in the form of muscular or intravenous injections.
- Parathyroid Hormone (PTH): High levels of parathyroid hormone (PTH) may result from a poor balance of calcium and phosphorus in the body. This can cause mineral bone disease. When kidney functioning deteriorates, phosphorous increases in blood resulting in increase of parathyroid hormones.
- Calcium-Calcium is used by muscle cells to contract and by nerve cells to propagate an impulse. Serum calcium routine blood test measures the levels of three types of calcium present in the blood, namely, citrate, lactate, phosphate and bicarbonate. High calcium in blood indicates that kidney is unable to filter excess calcium from the blood.
- Phosphorous-High phosphorous may signal impaired kidney functioning as kidney is unable to balance the body’s required phosphorous. Doctor may prescribe phosphate binders and diet low in phosphorous.
- Potassium– Potassium is a mineral which is required by nerves, muscles and heart to work in rhythm. A potassium level that is too high or too low may weaken muscles and change heartbeat. Normally, kidneys maintain proper electrolyte balance in the body by retaining appropriate levels of potassium and sodium and flushing out the excess through urine. When kidney functioning is impaired, body is unable to flush out the excess potassium leading to a buildup of potassium in the blood known as hyperkalemia. In extreme cases, high potassium in blood can cause paralysis or heart failure.
- Sodium– A sodium blood test may be part of a test called an electrolyte profile. An electrolyte panel is a blood test that measures sodium, along with other electrolytes, including potassium, chloride, and bicarbonate. Electrolytes are electrically charged minerals that help maintain fluid levels and the balance of chemicals in body called acids and bases. Sodium helps nerves and muscles work properly. Once body takes in enough sodium, the kidneys get rid of the rest by urine. When kidneys are not working properly, excess sodium remains in blood, called hypernatremia. Excess thirst, vomitting, diarrhea, infrequent urination are some symptoms of excess sodium.
- Bicarbonate- Bicarbonate (HCO3) is excreted and reabsorbed by the kidneys. This regulates body’s pH, or acid balance. Bicarbonate also works with sodium, potassium, and chloride, also called electrolytes. A low level of bicarbonate in blood may cause a condition called metabolic acidosis, or too much acid in the body. A wide range of conditions, including diarrhea, kidney disease, and liver failure, can cause metabolic acidosis.
- Serum Uric Acid-Uric acid is produced by oxidization of purine rich food inside the body. In patients with high uric acid, probability of kidney disease progression may increase.
- Blood Urea Nitrogen (BUN)-An individual with kidney disease may have higher BUN in blood. BUN, along with creatinine is used to calculate GFR.
URINE TEST:
- Proteinuria (protein in urine)-Healthy kidneys do not allow a significant amount of protein to pass through their filters. But filters damaged by kidney disease may let proteins such as albumin leak from the blood into the urine. Proteinuria can also be a result of overproduction of proteins by the body. If the protein loss is heavy, the urine has a frothy appearance, and would most likely be associated with other symptoms e.g. oedema, where there is an excess of water in the body tissues
- Albuminuria-Several proteins can be found in the urine, but the most relevant to kidney disease is albumin. Albumin is a protein found in the blood. A healthy kidney doesn’t let albumin pass from the blood into the urine. A damaged kidney lets some albumin pass into the urine.
- Urine Creatinine: This test estimates the concentration of urine and helps to give an accurate protein result. Protein-to-Creatinine Ratio: This estimates the amount of protein excreted in urine in a day and avoids the need to collect a 24-hour sample of urine.
- Urine Culture-Urine culture tests presence of protein, blood, pus, casts, crystals, etc in urine to analyse and diagnose the kidney functioning of the body.
OTHERS:
- nPNA: Normalized protein nitrogen or nPNA appearance is a test that may tell if one is eating enough protein. This measurement comes from lab studies that include a urine collection and blood work.
- Glomerular Filtration Rate (eGFR)- Serum creatinine and age race, gender, etc mathematically generate eGFR value, which is an estimate of how well the kidneys are functioning. If GFR falls below 30, a kidney disease specialist (called a nephrologist) should be approached for treatment.
- Albumin Creatinine Ratio (ACR)-Higher Albumin creatinine ratio is a marker for chronic kidney disease
Doctor may also suggest performing Electroencephalogram (EEG) and Electromyography (EMG)/ Nerve Conduction tests on diagnosis of CKD.
Some or all of the above tests may be repeated every month for three months or as per doctor’s advice for confirmation of kidney disease. Once kidney disease is confirmed through diagnosis, the stage of kidney disease is assessed by the nephrologist. Various stages of Chronic kidney disease (CKD) require different approach to diet, medication, lifestyle, procedures, etc. Read more on stages of kidney disease and treatment options.
To know about how kidney functions and is related to various vital organs of the body please read sections on role of kidney, kidney and hormone balance and kidney and other organs.