What is Kidney?
The kidneys are a pair of organs that filter blood and remove waste products from the body.
They are located in the abdomen, one on each side of the spine, and are about the size of a clenched fist
Function of Kidney
Where are your kidneys located?
Your kidneys are located just below your ribcage, behind your abdomen, with one on each side of your spine. They are positioned between your intestines and diaphragm.
What are the parts of the kidney?
Kidney capsule (renal capsule)
The renal capsule is made up of three layers of connective tissue or fat that encase the kidneys. It serves to protect them from injury, enhance their stability, and anchor them to surrounding tissues.
Renal Artery
The renal artery is a major blood vessel that regulates blood flow to the kidneys. At rest, most people’s kidneys receive just over 5 cups (1.2 liters) of blood per minute.
Renal Medulla
The renal medulla is the inner region of the kidney, housing most nephrons with glomeruli and renal tubules. These tubules transport urine to renal pelvis.
Renal Pelvis
The renal pelvis is the funnel-shaped structure in the kidney that collects urine and passes it down the ureters to the bladder, where it is stored before being excreted.
Renal Cortex
The renal cortex is the kidney’s outer layer, where nephrons start filtering blood. It also makes erythropoietin (EPO), a hormone that helps produce red blood cells.
Renal Papilla
These pyramid-shaped structures transport urine to the ureters. Dehydration and certain medications, particularly NSAIDs, can damage the renal papilla.
Renal Vein
The renal vein is the primary blood vessel that transports filtered blood from each kidney back to the heart.
How big is a kidney?
Each kidney measures approximately 4 to 5 inches in length, about the size of a fist.
What causes kidney damage?
Your kidneys play a vital role in your body, but various disorders can affect their function. Some common conditions that impact the kidneys include:
Chronic kidney disease (CKD) can reduce kidney function and is typically caused by diabetes or high blood pressure
A kidney infection happens when bacteria travel up the ureters. It causes sudden symptoms and is treated with antibiotics.
Kidney stones form crystals in urine and can block flow. Some pass naturally, while others may need treatment to break or remove them.
Renal cell carcinoma is the most common form of kidney cancer, developing in the kidney's filtering system for the majority of kidney cancer cases.
Kidney failure can be acute or chronic. End-stage renal disease is complete kidney failure, requiring dialysis to filter the blood.
Polycystic kidney disease (PKD) is a genetic condition that causes kidney cysts. It can lead to high blood pressure and kidney failure, requiring regular medical checkups.
Disorders
Countless other disorders can affect your kidneys.
Too much acid in the kidneys can cause serious health problems and may be life-threatening.
Nitrogen waste accumulates in your kidneys, and without treatment, azotemia can be life-threatening.
Glomerular diseases lead to inflammation or damage in your glomeruli, which may result in kidney failure.
In the medulla and papilla, sections of kidney tissue die, potentially breaking off and blocking the kidneys, which can result in kidney failure.
This sudden kidney infection leads to edema (swelling) in the kidneys and can be life-threatening.
Your kidneys may become inflamed, sometimes as a reaction to certain antibiotics, potentially resulting in kidney failure.
Excess fluid causes swelling in your calyces, where urine collection begins. Without treatment, caliectasis can lead to kidney failure.
Kidney damage can result from unmanaged diabetes or persistently high blood pressure.
Minimal change disease and nephrotic syndrome cause your kidneys to release excessive protein in your urine.
Proteinuria refers to elevated protein levels in your kidneys, which may indicate kidney damage.
Signs kidney problem
Most kidney problems show no symptoms in the early stages. As the damage progresses, you may begin to notice signs.
Cramping muscles
Dark urine or urine with blood in it
Itchy, dry skin
More frequent urination
Puffy eyes or swollen ankles and feet
Sleep problems, fatigue and lack of appetite
Common tests
Advanced Imaging
Imaging techniques such as X-ray, CT scan, MRI, ultrasound, or nuclear medicine can reveal kidney abnormalities or obstructions.
Blood Tests
Blood tests indicate how effectively your glomeruli filter waste from your blood.
Kidney Biopsy
A kidney biopsy involves removing a small tissue sample to analyze under a microscope for potential abnormalities.
Ureteroscopy
An endoscope is inserted through the urethra into the bladder and ureters to examine for abnormalities.
Urinalysis
A urinalysis examines your urine, detecting substances like protein or blood.
CT Scan
A painless imaging test that uses X-rays to create 3D pictures of the kidneys, ureters, and bladder
How to keep your kidney healthy
Regular checkups, along with blood and urine tests, are essential for monitoring kidney health. You can lower your risk of kidney problems by taking preventive measures.
Quit Smoking
Cutting Out Excess Salt
Drinking Water
Daily Exercise
Limiting use of NSAID
Maintaining Weight
Monitoring Blood Pressure
Beware Blood Sugar
Creatinine Test
A creatinine test is a measure of how well your kidneys are performing their job of filtering waste from your blood.
Creatinine is a chemical compound left over from energy-producing processes in your muscles. Healthy kidneys filter creatinine out of the blood. Creatinine exits your body as a waste product in urine.
A measurement of creatinine in your blood or urine provides clues to help your doctor determine how well the kidneys are working.
Purposes
- To make a diagnosis if you have signs or symptoms of kidney disease
- To screen for kidney disease if you have diabetes, high blood pressure or other conditions that increase the risk of kidney disease
- To monitor kidney disease treatment or progression
- To monitor for side effects of drugs that may include kidney damage or altered kidney function
- To monitor the function of a transplanted kidney
Results
Results from creatinine in blood or urine are measured and interpreted in many ways, including the following:
Serum Creatinine Level
Serum creatinine is reported as milligrams of creatinine to a deciliter of blood (mg/dL) or micromoles of creatinine to a liter of blood (micromoles/L). The typical range for serum creatinine is:
- For adult men, 0.74 to 1.35 mg/dL (65.4 to 119.3 micromoles/L)
- For adult women, 0.59 to 1.04 mg/dL (52.2 to 91.9 micromoles/L)
Glomerular Filtration Rate (GFR)
The measure of serum creatinine may also be used to estimate how quickly the kidneys filter blood (glomerular filtration rate). Because of variability in serum creatinine from one person to another, the GFR may provide a more accurate reading on kidney function.
Creatinine Clearance
Creatinine clearance is a measure of how well the kidneys filter creatinine out of the bloodstream for excretion in urine.
The typical range, by age, for creatinine clearance in women is as follows:
- 18 to 29 years: 78 to 161 mL/min/BSA
- 30 to 39 years: 72 to 154 mL/min/BSA
- 40 to 49 years: 67 to 146 mL/min/BSA
- 50 to 59 years: 62 to 139 mL/min/BSA
- 60 to 72 years: 56- to 131 mL/min/BSA
Albumin/Creatinine Ratio
Another interpretation of urine creatinine count is called the albumin/creatinine ratio. Albumin is a protein in blood. Healthy kidneys generally don’t filter it out of the blood, so there should be little to no albumin found in the urine.
Albumin/creatinine ratio describes how much albumin is in a urine sample relative to how much creatinine there is. The results are reported as the number of milligrams (mg) of albumin for every gram (g) of creatinine. Results indicating a healthy kidney are:
- For adult men, less than 17 mg/g
- For adult women, less than 25 mg/g