Dr K Bhanu Prasad
Kidneys are often deprived of the respect they deserve. But, they are truly impressive and knowing them better helps to keep them healthy. Nephrology is the branch of medicine concerned with the diagnosis and treatment of conditions related to the kidneys. Doctors who specialize in kidney disease are called nephrologists.
Kidneys are two bean-shaped organs about five-inches long, three-inches wide and one-inch thick located in your back on each side of the spine. They are situated above the waist, with the left kidney a little higher and a little larger. Inside the kidneys are nephrons (filters), which are tiny units where the filtering of excess fluids and dissolved particles occurs. There are between 9 to 11 lakhs nephrons in each kidney.
Functions of Kidney
Most think kidneys are just responsible for producing urine, but there’s a lot more to it. In addition to removing extra fluid and water from your body, kidneys:
- Filter the blood
- Balance fluid content in the body
- Produce the enzyme renin that helps control blood pressure
- Produce the hormone erythropoietin to help make red blood cells
- Activate vitamin D to maintain healthy bones
- Adjust levels of minerals and other chemicals to keep the body working properly
The basic function of kidneys begins when you eat and drink. After the body takes the nutrients it needs, the extras become wastes. Some of the waste winds up in the blood and needs to be filtered out. The blood gets circulated through the body with every beat of the heart. It’s the job of the kidneys — with their millions of nephrons — to filter and clean out the blood and remove the extra fluids. The extra fluid and waste becomes urine and travels from the kidneys down the ureters to the bladder until eliminated through the urethra.
Removing waste is not the only job of the kidneys. In addition to filtering, the kidneys monitor the levels of chemicals, salts and acids in the blood. Inside the nephrons are sensors that keep track of sodium, phosphorus, calcium and potassium. When levels are high, the kidneys signal to remove the excess from your blood for elimination.
Another important task of the kidneys is to monitor and regulate certain body functions. An enzyme called renin is secreted by the kidneys to control blood pressure. A hormone called erythropoietin tells the bone marrow to make red blood cells, and one called calcitriol (vitamin D) helps to keep bones strong.
Problems with the kidneys may be caused by:
- Aging: As we age, changes in the structure of the kidneys can cause them to lose some of their ability to remove wastes from the blood.
- Illness or injury: Damage to the kidneys caused by illness, infections like malaria, dengue can also prevent them from filtering the blood completely or block the passage of urine. Diabetes and high blood pressure (hypertension) are 2 leading causes of kidney disease.
- Toxicity: The kidneys may be damaged by substances, such as certain medicines like painkillers, a build up of some substances in the body, or toxic substances.
Each person may have different symptoms, but majority of patients have no symptoms, hence kidney disease is called a silent killer. The following are the most common symptoms of kidney disease, Frequent headaches, Fatigue, Itchiness all over the body, Blood in the urine, Loss of appetite, Nausea and vomiting, Puffiness around eyes, swelling of hands and feet, Skin may darken, Muscle cramps or pain in small of back just below the ribs (not aggravated by movement), High blood pressure etc.
Often these symptoms may look like other health problems, it’s better to talk to your healthcare provider for an appropriate diagnosis.
Kidneys could be affected by a number of diseases, some of the critical ones are:
In people with diabetic nephropathy, damage occurs to the capillaries of the kidney as a result of long-term diabetes. Symptoms do not become clear until years after the damage starts to develop. Some of the symptoms include headaches, tiredness, nausea, swollen legs, itchy skin etc.
Nephrotic syndrome or Glomerulonephritis
Damage to the kidney function causes protein levels in the urine to increase. This results in a protein shortage throughout the body, which draws water into the tissues.
Stones can form as a solid build-up of minerals in the kidney. They can cause intense pain and might affect kidney function if they block the ureter.
These tend to result from bacteria in the bladder that transfer to the kidneys. Symptoms include lower back pain, painful urination, and sometimes fever. Changes in the urine may include the presence of blood, cloudiness, and a different odor.
Kidney infections are more common in women than in men, as well as in women who are pregnant.
In people with renal failure, the kidneys can’t filter out waste products from the blood effectively. If the failure is due to a disease, the cure may not be complete, however if it is due to an injury, such as the overuse of medication, the condition is often reversible with treatment.
It is a condition with water on the kidney. It usually occurs when an obstruction prevents urine from leaving the kidney, causing intense pain. In time if it is not addressed, the kidney might atrophy or shrink.
A reaction to medications or bacteria can inflame the spaces within the kidney. Treatment usually involves removing the cause of inflammation or changing a course of medication.
These can be benign or malignant. Benign cancers do not spread or attack tissue, but malignant cancers can be aggressive. The most common malignant kidney cancer is renal cell carcinoma.
Kidney disease diagnosis involves, first determining whether the patient belongs to any of the high-risk groups. They will then run a battery of tests to see if the kidneys are functioning properly. These tests may include:
The urine sample is tested for albumin, a protein that can be passed into the urine when the kidneys are damaged.
Blood urea and Serum Creatinine tests
Creatinine is a waste product; it’s released into the blood when creatine (a molecule stored in muscle) is broken down. The levels of creatinine in the blood will increase if the kidneys aren’t working properly.
Glomerular filtration rate (GFR)
This test will measure how well your kidneys are working and determine the stage of kidney disease.
Ultrasound or computed tomography (CT) Scan
Ultrasounds and CT scans produce clear images of kidneys and urinary tract. The pictures allow doctor to see if the kidneys are too small or large. They can also show any tumors or structural problems that may be present.
During a kidney biopsy, a small piece of tissue is removed from the kidney while the patient is sedated. The tissue sample helps doctor to determine the type of kidney disease one has and how much damage has occurred.
The kidney disease can be prevented by making dietary and lifestyle changes. Making changes to ones diet is just as important as taking medication. Adopting a healthy lifestyle can help prevent many of the underlying causes of kidney disease. Some suggested changes include:
- control diabetes through insulin injections
- cut back on foods high in cholesterol
- cut back on salt
- start a heart-healthy diet that includes fresh fruits, veggies, whole grains and low-fat dairy products
- limit alcohol consumption
- quit smoking
- increase physical activity
- lose weight
(Dr K Bhanu Prasad, is a Consultant Nephrologist, Apollo Hospitals, Hyderguda)