In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organs that are a multilobar multipapillary form of mammalian kidney, usually without signs of external lobulation. They are located on the left and right in the retroperitoneal space, and in adult humans are about 12 centimetres in length. They receive blood from the paired renal arteries; blood exits into the paired renal veins. Each kidney is attached to a ureter, a tube that carries excreted urine to the bladder.
Nephrology is a specialty of adult internal medicine and pediatric medicine that concerns the study of the kidneys, specifically normal kidney function and kidney disease, the preservation of kidney health, and the treatment of kidney disease, from diet and medication to renal replacement therapy. The word "renal" is an adjective meaning "relating to the kidneys", and its roots are French or late Latin. Whereas according to some opinions, "renal" and "nephro" should be replaced with "kidney" in scientific writings such as "kidney medicine" or "kidney replacement therapy", other experts have advocated preserving the use of renal and nephro as appropriate including in "nephrology" and "renal replacement therapy", respectively.
Kidney stone disease, also known as nephrolithiasis or urolithiasis, is a crystallopathy where a solid piece of material develops in the urinary tract. Kidney stones typically form in the kidney and leave the body in the urine stream. A small stone may pass without causing symptoms. If a stone grows to more than 5 millimeters, it can cause blockage of the ureter, resulting in sharp and severe pain in the lower back or abdomen. A stone may also result in blood in the urine, vomiting, or painful urination. About half of people who have had a kidney stone are likely to have another within ten years.
Clinical chemistry is a division in medical laboratory sciences focusing on qualitative tests of important compounds, referred to as analytes or markers, in bodily fluids and tissues using analytical techniques and specialized instruments. This interdisciplinary field includes knowledge from medicine, biology, chemistry, biomedical engineering, informatics, and an applied form of biochemistry.
Proteinuria is the presence of excess proteins in the urine. In healthy persons, urine contains very little protein; an excess is suggestive of illness. Excess protein in the urine often causes the urine to become foamy. Severe proteinuria can cause nephrotic syndrome in which there is worsening swelling of the body.
Urinalysis, a portmanteau of the words urine and analysis, is a panel of medical tests that includes physical (macroscopic) examination of the urine, chemical evaluation using urine test strips, and microscopic examination. Macroscopic examination targets parameters such as color, clarity, odor, and specific gravity; urine test strips measure chemical properties such as pH, glucose concentration, and protein levels; and microscopy is performed to identify elements such as cells, urinary casts, crystals, and organisms.
Hematuria or haematuria is defined as the presence of blood or red blood cells in the urine. "Gross hematuria" occurs when urine appears red, brown, or tea-colored due to the presence of blood. Hematuria may also be subtle and only detectable with a microscope or laboratory test. Blood that enters and mixes with the urine can come from any location within the urinary system, including the kidney, ureter, urinary bladder, urethra, and in men, the prostate. Common causes of hematuria include urinary tract infection (UTI), kidney stones, viral illness, trauma, bladder cancer, and exercise. These causes are grouped into glomerular and non-glomerular causes, depending on the involvement of the glomerulus of the kidney. But not all red urine is hematuria. Other substances such as certain medications and foods can cause urine to appear red. Menstruation in women may also cause the appearance of hematuria and may result in a positive urine dipstick test for hematuria. A urine dipstick test may also give an incorrect positive result for hematuria if there are other substances in the urine such as myoglobin, a protein excreted into urine during rhabdomyolysis. A positive urine dipstick test should be confirmed with microscopy, where hematuria is defined by three or more red blood cells per high power field. When hematuria is detected, a thorough history and physical examination with appropriate further evaluation can help determine the underlying cause.
Assessment of kidney function occurs in different ways, using the presence of symptoms and signs, as well as measurements using urine tests, blood tests, and medical imaging.
A urine test is any medical test performed on a urine specimen. The analysis of urine is a valuable diagnostic tool because its composition reflects the functioning of many body systems, particularly the kidneys and urinary system, and specimens are easy to obtain. Common urine tests include the routine urinalysis, which examines the physical, chemical, and microscopic properties of the urine; urine drug screening; and urine pregnancy testing.
Pyelonephritis is inflammation of the kidney, typically due to a bacterial infection. Symptoms most often include fever and flank tenderness. Other symptoms may include nausea, burning with urination, and frequent urination. Complications may include pus around the kidney, sepsis, or kidney failure.
Pyuria is the condition of urine containing white blood cells or pus. Defined as the presence of 6-10 or more neutrophils per high power field of unspun, voided mid-stream urine, it can be a sign of a bacterial urinary tract infection. Pyuria may be present in people with sepsis, or in older people with pneumonia. Others additionally require discoloration, clouding or change in the smell of urine for a pyuria to be present. Without these additional features, there is said to be leukocyturia.
Uroscopy is the historical medical practice of visually examining a patient's urine for pus, blood, or other symptoms of disease.
Aminoaciduria occurs when the urine contains abnormally high amounts of amino acids. In the healthy kidney, the glomeruli filter all amino acids out of the blood, and the renal tubules then reabsorb over 95% of the filtered amino acids back into the blood.
Renal papillary necrosis is a form of nephropathy involving the necrosis of the renal papilla. Lesions that characterize renal papillary necrosis come from an impairment of the blood supply and from subsequent ischemic necrosis that is diffuse.
Bacteriuria is the presence of bacteria in urine. Bacteriuria accompanied by symptoms is a urinary tract infection while that without is known as asymptomatic bacteriuria. Diagnosis is by urinalysis or urine culture. Escherichia coli is the most common bacterium found. People without symptoms should generally not be tested for the condition. Differential diagnosis include contamination.
Urologic diseases or conditions include urinary tract infections, kidney stones, bladder control problems, and prostate problems, among others. Some urologic conditions do not affect a person for that long and some are lifetime conditions. Kidney diseases are normally investigated and treated by nephrologists, while the specialty of urology deals with problems in the other organs. Gynecologists may deal with problems of incontinence in women.
Walter De Brouwer is a Belgian-born internet and technology serial entrepreneur and semiotician. He is the former CEO of doc.ai and of Scanadu. As a serial entrepreneur, as of 2013, he took part in the creation of over 35 companies, including two that became publicly traded through Initial Public Offering.
A urine test strip or dipstick is a basic diagnostic tool used to determine pathological changes in a patient's urine in standard urinalysis.
Scanadu was a Silicon Valley-based company that developed new medical devices from 2011 to 2016. In June 2020, after relaunching under the name inui Health, it was acquired by the Israeli healthcare startup Healthy.io.
Jonathan Adiri is an Israeli digital healthcare entrepreneur and an advisor to former Israeli president Shimon Peres.
