Kidney function tests

Kidneys are two-bean-shaped organs located in the middle of your back, just below your ribcage. They are about 12 cms long almost the shape of a man’s palm

Functions:
1. Kidneys make urine to purify our blood. Along with urine our body discards toxic wastes and excess water.
2. Kidneys help regulate our blood pressure.
3. Kidneys secrete hormone, which controls formulation of RBCs in bone marrow thereby maintaining hemoglobin in the body. If our kidneys function gets impacted our haemoglobin levels too can go down.
4. Healthy functioning of kidneys is crucial to manage the balance between calcium and phosphate. Our blood has both these minerals and their balance is essential for the healthy functioning of our bones. Vitamin D is essential for bone metabolism and mineralisation. Active form of vitamin is formed in kidneys along with liver. When our kidneys do not function well, balance between calcium and phosphate is lost, which is detrimental to our bone health.
Need for renal function test: Renal function tests evaluate the health status of kidneys and how well they are functioning. Two components in the blood are crucial in determining the status of kidneys’ health—urea and creatinine. Of the two, creatinine is a sensitive indicator of renal function. Simple urine routine examination is also a kind of good indicator of kidney tests.
Threats to your kidney health
The two most common causes of kidney disease are diabetes and high blood pressure. 30 to 40% patients of diabetes develop kidney disease called as Diabetic Nephrology (DN). High blood pressure can damage your kidneys. If your family has a history of kidney problems, you may be at risk for kidney disease.
Each kidney has 1 million functioning units known as nephrons. Normally, majority of nephrons are dormant and usually kidney damage is not picked up unless a patient or doctor is vigilant. Most kidney diseases attack the nephrons—cells in the kidney that filter blood, causing them to lose their filtering capacity. Damage to the nephrons may happen quickly, often as the result of injury or poisoning. Kidney is a resilient organ and often withstands damage for a long period of time before any symptom surfaces. Most kidney diseases attack both kidneys simultaneously.

Watch out
(1) Blood Urea Nitrogen test (BUN): Urea is a by-product of protein metabolism. This waste product is formed in the liver, then filtered from the blood and excreted in the urine by the kidneys. High BUN levels can indicate kidney dysfunction, but it is not a reliable indicator, because other factors can impact the levels too:
• Too much protein breakdown like in starvation
• Very high protein intake
• Congestive heart failure
• Functioning of liver
• Heart attack
• Bleeding in the gut
• Decrease in the blood volume like in burns, dehydration or shock
• Obstruction in the urinary tract due to a tumour, stones, or prostatic hypertrophy
• Drugs used in gout, infections, epilepsy, blood pressure, pain relief, etc may raise blood urea.
(2) Creatinine: This sensitive marker for kidneys’ health is produced when our muscles are put to use. Creatinine unlike blood-urea-nitrogen is a sensitive and reliable marker of renal function because it is affected very little by the way our liver functions. Again, more muscular people may have higher levels of creatinine than a small-framed woman.

(3) Other blood tests– Measurement of the blood levels of other elements regulated in part by the kidneys can also be useful in evaluating kidney function. These include sodium, potassium, chloride, bicarbonate, calcium, magnesium, phosphorus, protein, uric acid, and glucose.

(4) USG (Ultra Sono Gram) tests for KUB (Kidney Uretra Bladder) area is also very helpful in diagnosing kidney ailments.
Renal Profile Tests – Normal Values
Test Normal Values
Blood Urea 15-50mgs/dl
Blood Urea Nitrogen 5-20 mgs/dl
Serum Creatinine 0.4-1.2 mgs/dl
Serum Calcium 8.8-11 mgs/dl
Serum Phosphorus 2.0-5.0 mgs/dl
Serum Magnesium 1.5-2.5 mgs/dl
Serum Sodium 134-146 m Eq/lt
Serum Potassium 3.5-5.0 m Eq/lt
Serum Bicarbonate 22-26 m Eq/lt

—Dr. R Hotc

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