Health of any human being is dependent on the state of 6 major organs in the body. They are the brain, the heart, the lungs, the liver, the pancreas and the kidneys. Although there are other organs that also help maintain normal health majority of the problems are caused by pathology affecting one of the 6 organs. Important functions performed by the kidney: Excretion of toxic waste formed in the body Important in regulating blood pressure Maintenance of salt and water balance in the body Role in the synthesis of vitamin D and production of red blood cells (RBC) Kidneys produce urine through which most of the waste products formed in the body are excreted. If the kidneys malfunction, toxic waste products start to accumulate causing ill health. The kidneys are also responsible for maintaining the right amount of salt and water in the body (electrolyte balance). Any imbalance in the electrolyte levels can again cause serious ill health ranging from lethargy to unconsciousness and cardiac arrest. How does the Kidney function: Normally there are 2 kidneys through which a large volume of circulating blood flows through. The blood containing salts, waste products and all the other components flow through tiny blood vessels bundled together in structures called glomerulus. These are the specialised filtering units in the kidney. There are approximately 1 million glomeruli in each kidney. The fluid that is filtered from blood passes through a series of tubules. As the filtrate flows through the tubules, all essential salts together with the right amount of water is reabsorbed back in to the circulation. The rest of the water together with the toxic waste products pass through the ureter and stored in the bladder to be excreted later as urine. Urine is an ultrafiltrate of blood plasma. It is slightly acidic and normally will not contain blood, protein or sugar. If any of these are present it indicates an underlying disease. If the glomeruli or tubules are affected by disease, chemicals or poison, the kidney function will be impaired resulting in accumulation of toxins, waste products and excess water. The electrolyte balance will also be affected. The result is kidney failure. The grade of failure will depend on the extent of damage. Kidneys Can Be Damaged by: Environmental Pollutants Severe Dehydration Trauma to the Kidney Myoglobin released when muscles are crushed during an accident Hypertension Diabetes Mellitus Cancer Anti inflammatory Drugs like Ibuprofen Antibiotics like Gentamycin Iodine containing medications used in scans. Symptoms of Kidney Failure: Lethargy Tiredness Breathlessness Loss of appetite Generalised swelling (oedema) Puffiness of face Palpitation Feeling fait Checking Your Renal Function Renal or kidney function tests (RFTs) are done to assess how well the kidneys are working. The tests are done when there is suspicion of impaired kidney function or it is done as part of a routine health check. If done as part of a routine health check a simple blood test alone will suffice. If a thorough investigation is required, urine and blood are both checked. Blood Test The blood should be checked for levels of urea, creatinine, sugar, electrolytes and glomerular filtration rate (eGFR). If any of the levels are abnormal further assessment should be undertaken. Glomerular filtration rate (GFR) is a measure of the function of the kidneys. Normal Glomerular Filtration Rate (eGFR) is around 90. This normally declines with age. Rates below 50 indicate renal impairment. A rate below 15 indicates severe renal failure that will require dialysis or kidney transplant to survive. Urine Test Urine is usually tested for the presence of blood, sugar, proteins and signs of infection. Normally none of these should be present in healthy individuals. Albumin Creatinine Ratio (ACR) is an important test on the urine. Albumin, a protein should not normally be present in the urine. Measuring this will indicate the degree of kidney disease. A quick assessment of renal function can be done by checking serum creatinine, blood urea and eGFR. If any of them are abnormal more thorough check on kidney function should be undertaken. Other Tests After routine tests if kidney pathology is suspected ultrasound and/or MRI scan may be indicated. Points to Remember: Kidneys play an important role in maintaining health. You may be unaware that the kidney is failing until nearly 90% of function is lost Kidney function may be affected by not drinking enough water Function may also be affected by routine every day drugs taken for prolonged periods If you are on any long-term medication, have regular blood test to check Kidney function If you are over 60 it is a good idea to have kidney function checked whenever a routine health check is done. High blood pressure is a leading cause of kidney disease. Diabetes is one of the leading causes of kidney failure. High cholesterol may indicate risk for heart disease, a major risk factor for kidney disease. Most people with early kidney disease do not have symptoms. That is why it is important to be tested regularly. K. Badrinath, FRCS This Topic is discussed in the “Forum” under
Kidney Function
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