Categories: Nephrology

Understanding Kidney Function Test

Each person has a pair of kidneys located on the posterior abdominal wall below ribs. The normal function of the kidney includes filtering the waste products out of human blood and excreting them in the urine. Apart from filtering roles, there are other roles including synthesis of Vitamin D, hemoglobin, and certain hormones that are needed for maintaining the blood pressure. Abnormalities with one or both kidneys can be identified with the presence of certain signs, symptoms, and diagnostic tests.

Certain conditions causing abnormalities in kidney function:

  • Diabetes
  • High blood pressure
  • Chronic glomerulonephritis — inflammation and eventually scarring of the tiny filters (glomeruli) within your kidneys
  • Polycystic kidney disease

Symptoms causing worry are:

  • traces of blood in the urine
  • frequent urination
  • trouble initiating urination
  • painful urination
  • swelling of hands and feet due to excessive buildup of fluids in the body
  • fever with chills and rigors

Understanding Kidney function test:

Most tests are directed towards the calculation of glomerular filtration rate which is the rate at which kidneys are able to carry out the process of filtration or purification of blood, of its various waste products like urea, creatinine, acids, etc.

  1. Urine test – Including urine routine microscopy is directed towards detecting the presence of protein or blood in the urine. A damaged kidney is unable to retain protein, which gets excreted into the urine (proteinuria). Proteins are too big a molecule to be excreted by a normal kidney and are usually retained in the body. In order to quantify the amount of protein leaking in the kidney other urine tests which are performed commonly include spot urine protein/creatinine ratio and 24-hour urine protein excretion (gold standard). The protective barrier which performs the filtering function of the kidney in the body is known as the glomerulus. A damaged kidney is also usually unable to retain red blood cells in the body, which may pass in urine (hematuria).

Glomerular filtration rate (GFR) < 60 milliliters/minute/1.73m2 is indicative of chronic kidney disease Stage-3 or above (significant renal dysfunction). It can be calculated by 24-hour urine creatinine clearance (gold standard), which is a test performed routinely in all standardized labs or by radioisotope imaging studies like DTPA scan.

  1. Blood Tests
  2. Serum Creatinine – Creatinine is a byproduct of muscle metabolism in the body. Both kidneys have an important role in filtering creatinine from the body. In the case of kidney disease, one is unable to excrete creatinine from the body and its level in the body starts to rise (> 1mg/dl). This leads to a series of adverse effects on the body which manifests as various clinical symptoms like weakness, nausea, vomiting, decreased appetite, itching all over the body, and so on. Serum creatinine is the single most important predictor of kidney disease in our body.
  3. Blood Urea Nitrogen is normally valued between 7 and 20 mg/dL. The test is used to measure the amount of nitrogen in the blood. It is a byproduct of protein metabolism and is usually high in the case of kidney disease, although other conditions like intake of medications like aspirin, specific antibiotics, and a few supplements can also cause its value to rise.

Lifestyle and Diet modifications:

  • Limit foods high in sugar and fat content
  • Five serving of fruits and vegetables each day
  • Take a low-salt diet
  • Monitor and control your weight, blood cholesterol, blood sugar, and blood pressure levels
  • Keep yourself well hydrated (at least 2.5 L of fluids in 24 h)
  • Regular physical activity for at least 30 min a day, could be:
  1. Walking
  2. Cycling
  3. Swimming
  4. Lightweights

Recognition and awareness of warning signs and timely intervention can mean the difference between early detection and treatment of kidney disorder or kidney failure which could end up with dialysis, kidney transplant, or even death.

Dr. Sudeep Singh Sachdev, Consultant – Nephrology, Kidney Transplant – Adult, Narayana Superspeciality Hospital, Gurugram

Narayana Health

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