Kidney inflammation, glomerulonephritis: what are the causes and symptoms?

Kidney inflammation, nephritis, is the general name for inflammation of the tubules, tissue or glomeruli in the kidneys. It can affect one or both kidneys at the same time.

Inflammation in the kidneys affects the function of the kidneys, their ability to filter and excrete waste products. It can cause protein to be excreted in the urine and impair water absorption, leading to swelling.

Kidneys

The kidney (ren, nephros) is a paired organ. It is located in the hip region just below the edge of the rib cage.

The right kidney tends to be lower and is slightly smaller than the left.

On top of the kidney is the adrenal gland with the function of secreting hormones (mineralocorticoids - aldosterone, glucocorticoids - cortisol, catecholamines - adrenaline, noradrenaline and androgens - sex hormones).

Structure of the kidneys

The kidney consists of a cortex and a medulla.

The marrow is made up of pyramidal formations. The apex of these formations is surrounded by the renal calyces, which are responsible for collecting the definitive urine. The calyces pass into the renal pelvis.

The renal cortex contains nephrons, the basic structural and functional unit of the kidney.

There are approximately one million nephrons in one kidney.

The nephron consists of the Malpighian body and the tubule (a set of ducts). The tubule is both proximal and distal and are connected by a loop of Henle.

The Malpighian body consists of the glomerulus (a cluster of blood capillaries) and Bowman's pouch, which surrounds the glomerulus.

The glomerulus produces urine, called primary urine, by filtration of plasma. The primary urine is drained through a coiled duct into the foramen of Henle.

In 24 hours, the kidneys filter 2,000 litres of blood. They remove waste and maintain acid-base, water and mineral balance.

Urine production

The glomerulus filters blood from blood cells and proteins.

The filtrate then passes through the tubules of the nephron. Water, glucose, ions and amino acids are absorbed and resorbed back into the blood. Only waste substances remain in the tubules, forming secondary, definitive urine.

Secondary urine with waste substances flows into the collecting ducts, renal calyces, renal pelvis, ureter, bladder, urethra, and is expelled from the body into the urethra.

In a day, the kidneys produce approximately 190 to 200 litres of primary urine and excrete approximately 1.5 to 2 litres of definitive urine. This is called diuresis.

The hourly diuresis is 0.5-1.5 ml per kilogram of weight.

Urine is under normal conditions:

• Clear
• Straw yellow
• Its pH is 5.5-6.5
• It contains minerals, creatinine, amylase, urea, uric acid and others
• In a healthy person, there is no protein, sugar, bilirubin or blood in the urine

Kidney function

• Excretory, filtering - filters the blood and removes waste substances, foreign substances such as drugs, and forms urine
• Maintain fluid balance in the body
• Maintain the balance of the internal environment
• Regulate blood pressure by secreting the hormone renin
• Influence erythrocyte production through the hormone erythropoietin
• Activation of vitamin D

Kidney inflammation

In the course of life and due to various factors, kidney inflammation can occur. Kidney inflammation is divided into several types depending on the part of the kidney in which the inflammatory process takes place.

The types of kidney inflammation can be

• Interstitial nephritis is inflammation of the space between the tubules, which also causes swelling of the kidney.
• Pyelonephritis is most commonly caused by a bacterial infection. It causes inflammation in the parenchyma of the kidney and in the renal pelvis
• Glomerulonephritis is inflammation in the glomeruli of the kidney.

Tubulointerstitial nephritis

In tubulointerstitial nephritis, inflammation spreads to all tissues of the kidney, which can lead to a decline in kidney function.

It is an infectious, allergic and toxic disease. It leads to a decrease in kidney function.

In children it occurs only sporadically.

It can occur acutely or chronically.

Tubulointerstitial nephritis often leads to kidney failure.

Acute non-infectious tubulointerstitial nephritis

Inflammation in the kidney can be non-infectious. In this case, the cause is not an infection, but, for example, a toxic effect of drugs or a hypersensitivity reaction to drugs.

In some cases, it is also the cause of renal insufficiency.

Acute infectious tubulointerstitial nephritis

Occurs when an infection enters or as an immune response to a systemic infection.

It can be caused by bacteria, viruses, toxoplasmosis and mycoplasmas.

Direct entry of bacteria into the kidney may be from the rectum by transfer of bacteria into the urinary tract. Other routes of transmission are blood poisoning and direct blood transmission.

Leptospirosis, also called Weil's disease, is caused by infection with leptospires. The source is mice, rats, which excrete infected urine. Infection is transmitted to humans by touch through injured skin or conjunctivae.

Chronic tubulointerstitial nephritis

Manifested by histological changes of the tubulointerstitium, scarring, tubular atrophy (shrinking of the tubules) and interstitial fibrosis (thickening, thickening of the tissue).

Pyelonephritis

Pyelonephritis belongs to the group of tubulointerstitial nephritis. It is an inflammatory process in the parenchyma of the kidney and in the renal pelvis. It is most often caused by bacterial infection.

Renal inflammation can be acute or chronic.

Acute pyelonephritis

It is most often caused by bacteria that enter the kidney by gradual penetration from the urinary tract.

Even asymptomatic bacteria in the urine or bladder inflammation can lead to kidney inflammation.

Risk factors

• Pregnant women who have slowed ureteral peristalsis are particularly at risk
• Urinary tract obstruction or congenital developmental defects
• Kidney stones, urinary tract injuries, kidney disease, diabetes mellitus may also contribute to pyelonephritis

A risk factor for kidney inflammation, especially in children, is vesicoureteral reflux. In this, urine from the bladder returns to the kidneys. However, it can also occur in adulthood when the outflow of urine from the bladder is stopped, for example by a stone.

In diabetics, acute kidney inflammation is 5 times more common and is also more often complicated by the formation of an abscess (a cavity filled with pus). Diabetics are also at risk of developing emphysematous forms of pyelonephritis.

Emphysematous pyelonephritis

Is a form of acute bacterial inflammation with necrotic form (tissue necrosis). There is gas formation in the parenchyma.

This form is rare. It occurs in diabetics, but patients with obstructive kidney disease are also at risk. It manifests as acute pyelonephritis with nausea, vomiting. Often leads to dehydration.

Emphysematous pyelitis (pneumopyonephrosis)

Is a more discrete form in which gas formation is confined to the tissue of the ureter. Manifests as emphysematous pyelonephritis.

Chronic pyelonephritis

Chronic pyelonephritis is characterized by chronic inflammation with scarring of the renal tubules and interstitial tissue.

Chronic pyelonephritis may be related to inflammatory processes occurring in the kidneys that are not caused by bacteria. They may be of metabolic, chemical or immunological origin.

It is often associated with renal failure.

It can arise from inflammation of the urinary tract, from other diseases damaging the kidneys, such as high blood pressure, vascular disease, vesicoureteral reflux (backflow of urine into the kidney).

Pyelonephritis in children

Children are more likely to suffer from lower urinary tract infections.

If the infection is not recognized early or is not adequately treated, pyelonephritis often leads to scarring of the kidneys. Scarring poses a risk of high blood pressure, with bilateral kidney involvement, limiting kidney function. It can even lead to kidney failure.

Distinguishing acute cystitis in children from acute pyelonephritis is crucial. It must be addressed quickly.

Treatment in children is different from that in adults. Every hour of untreated pyelonephritis increases the risk of scarring of the renal parenchyma.

Pyelonephritis in pregnancy

In pregnancy, pyelonephritis is one of the most common urinary tract complications. It occurs in approximately 2% of pregnant women.

In pregnancy, it is a serious infection that can lead to septic shock and premature delivery.

A high temperature puts the baby at risk as the metabolism is accelerated and the fetus requires increased oxygen supply through the blood.

Glomerulonephritis

It is one of the relatively common and serious diseases affecting the glomeruli, the kidney villi.

Acute glomerulonephritis is also called nephritic syndrome.

Immune and disease-inducing mechanisms are involved in its development. In such situations, so-called immune complexes are formed. They attack the glomerulus, the capillary wall and increase their permeability.

Antigens (bacteria, viruses and others) or the formation of antibodies against the kidneys are involved in the formation of immunocomplexes.

Glomerulonephritis can be primary or secondary. Primary occurs independently, affecting only the renal glomeruli. Secondary manifests as part of another disease. Glomeruli can be affected in systemic, vascular, metabolic diseases affecting other organs (lupus, diabetes).

It is most common in adolescents and in children under 3 years of age.

Possible complications of glomerulonephritis:

• Acute renal failure.
• Chronic kidney disease.
• High blood pressure
• Nephrotic syndrome

Read also our articles:

• Kidney diseases: from inflammation to stones to failure? And their symptoms
• Kidney care: how to regenerate and strengthen them?

Kidney infection is usually complicated by bladder inflammation.

The bacteria that caused the inflammation in the bladder can get into the kidneys.

Tubulointerstitial nephritis is most often caused by non-steroidal anti-inflammatory drugs (reduce fever, inflammation, pain) or viruses (Hantavirus, Cytomegalovirus, Epstein-Barr virus).

E. coli is responsible for 85% of cases of acute pyelonephritis. Others may be Klepsiella, Proteus.

Read:

• Escherichia coli: What infections does it cause and what is the treatment? (E. coli)
• What exactly is the hantavirus that recently appeared in China?
• Mononucleosis.

Glomerulonephritis

The cause of glomerulonephritis can be an infectious disease. The cause can also be unknown in some cases.

Infectious causes include:

Acute post-infectious postreptococcal glomerulonephritis - It is caused by sudden involvement of the glomeruli after an infectious disease. The origin of the disease is nephritogenic strains - hemolytic streptococci.

Streptococcal infection often occurs in the respiratory tract.

When and why does glomerulonephritis occur?

Acute post-infectious glomerulonephritis can occur after experiencing an infection caused by:

• Pneumococcus, staphylococcus, hepatitis B viruses, toxoplasmosis and other bacterial, viral and parasitic diseases
• After contracting bacterial endocarditis
• HIV

Read also:

• Bacteria, viruses and more: as agents of serious diseases?

Other causes include autoimmune diseases caused by the immune system attacking its own healthy tissues.

These include:

• Chronic inflammatory diseases - lupus
• The immune system makes antibodies against its own tissues in the kidneys and lungs - Goodpasture's syndrome
• IgA nephropathy caused by the accumulation of antibodies in the glomeruli

Other causes:

• Inflammation of blood vessels - vasculitis
• Sclerotic conditions: high blood pressure, diabetes melitus

Chronic tubulointerstitial nephritis

Causes:

• Obstruction preventing the outflow of urine - obstructive uropathy
• Pyelonephritis
• Immunological reaction
• After drug use - post-drug nephrotoxicity in toxic reaction to drugs (analgesics, antiphlogistics)
• Metabolic diseases - diabetes mellitus, nephrocalcinosis, nephrolithiasis and others
• Congenital and systemic diseases

Prevention of urinary tract infections and kidney inflammation

• Adequate hygiene - sufficient but not excessive genital care, especially in women. Excessive washing and use of soap irritates the skin and mucous membranes of the genitals.
• All women and girls should wipe from front to back (after urination, after stool).
• Change pads more often. It is important for women to change their menstrual pads frequently during menstruation.
• Wearing appropriate underwear (cotton underwear and avoiding thong-type panties, which bind bacteria from the rectum and increase the risk of transferring them to the genitals).
• If bacteria have entered the urethra, urination is recommended to expel them.
• Not retaining urine.
• Adequate drinking so that the kidneys can function properly and excrete urine. Water, weak teas and mineral waters are recommended. Chamomile, urological tea, cranberry juice or a mixture of burdock, goldenseal and deaf-head are good for urinary tract infections.
• Avoid cold in the pelvic area, hips and legs.
• Do not take excessive doses of vitamin C and calcium, which promote the formation of kidney stones.
• When changing a newborn and in infants, clean the baby from front to back to prevent the transfer of bacteria from the stool to the urinary tract.
• Change out of swimwear after swimming in a public pool and after leaving the water. Do not leave them wet on.

Kidney inflammation (nephritis) is not always recognisable by symptoms.

Warning signs of inflammation may include:

• Foamy, bubbly urine or dark-colored urine.
• Decreased frequency of urination
• Swelling of ankles, feet
• Weight gain due to water retention in the body
• Headache
• Drowsiness
• High blood pressure

Tubulointerstitial nephritis

In non-infectious nephritis, symptoms are initially varied.

It may manifest as inflammation of the urinary tract:

• Increased temperature
• painful, difficult urination - dysuria
• visible change in urine colour to white - pyuria, urine is cloudy with visible signs of pus
• pain in the sacral area
• presence of protein in the urine - proteinuria
• blood in the urine - haematuria

Read also:

• Blood in the urine. As a symptom of these diseases, you would certainly not expect it
• Cloudy urine: what are its causes pale, white, foamy or cloudy urine?
• Dark urine: what are its main causes.
• Smelly urine

Tubulointerstitial nephritis is not always detected in time due to non-specific symptoms.

Symptoms of tubulointerstitial nephritis

• Elevated temperature, fever (which may not manifest itself, mainly due to the use of drugs that lower body temperature)
• Fatigue
• Dislike of food, vomiting
• Headache
• In children, abdominal pain
• Decreased urine output - oliguria
• Excessive urine output - polyuria
• Blood in the urine - haematuria
• Joint pain
• In hypersensitivity reactions, symptoms appear several days or even weeks after administration of the drug as maculopapular exanthema (skin seeding of varying size)
• Kidney enlargement, which in some cases is palpable
• Pain in the lumbar region or in the side
• Tenderness in the flank
• Swelling of the face and lower limbs
• Increased blood pressure
• Symptoms of kidney failure

Chronic tubulointerstitial nephritis

Symptoms that would indicate worsening chronic kidney disease are mostly absent.

Sometimes it is only manifested by slightly elevated blood pressure.

As nephritis progresses, symptoms of kidney failure begin to appear, such as:

• itching of the body
• fatigue
• lack of appetite
• nausea, vomiting
• difficulty breathing

Analgesic nephropathy occurs as a result of prolonged use of analgesics (aspirin, paracetamol and others). Symptoms of gastric ulcer and digestive problems, anaemia often occur. Later, high blood pressure also appears. The use of analgesics poses an increased risk of kidney cancer.

Pyelonephritis

In acute pyelonephritis, the kidneys swell considerably and abscesses may appear on the cortex.

Symptoms of acute pyelonephritis:

• Pain on urination
• Urge to urinate
• Urge to urinate at night
• Blood in the urine
• General discomfort
• Nausea to vomiting, sometimes diarrhea
• Increased temperature, usually up to 39 °C, sometimes up to 40 °C
• Increased pulse
• Chills, chills
• Pain in the side
• Malaise
• Typical kidney pain is common: dull pain at the kidney site that does not radiate to the surrounding area
• Urine: cloudy, smelly
• When using a test strip, positive for protein, blood, leukocytes, nitrite

Chronic pyelonephritis

In chronic pyelonephritis, the kidney is smaller, shrunken and scarred on the surface.

The kidney has an asymmetrical shape.

In chronic pyelonephritis, there may be signs of acute inflammation. It may also be completely asymptomatic or have only mild symptoms that are not noticed or not given importance.

Glomerulonephritis

Symptoms:

• Discoloration of the urine to pink or dark brown - hematuria, which means blood in the urine
• Foamy or bubbly urine - proteinuria, from excessive protein in the urine
• High blood pressure
• Swelling of the face, hands and feet caused by water retention in the urine
• Reduced number of urinations than usual
• Nausea, vomiting
• Muscle cramps
• Fatigue
• Nephritic syndrome - actual glomerular involvement
• Nephrotic syndrome - long-term glomerular damage
• Acute or chronic kidney damage
• Kidney failure

Difference between nephritic and nephrotic syndrome (table)

Acute postinfectious glomerulonephritis

Occurs 1-3 weeks after a streptococcal throat infection(strep throat) or 3-6 weeks after a streptococcal skin infection.

Occurs in persons whose streptococcal infection has not been treated with antibiotics or treatment has been inadequate.

Symptoms:

• Blood in the urine, which may not be visible to the naked eye, to a visible bloody discoloration of the urine. Urine may be up to a red, dark brown color
• Arterial hypertension
• Headache
• Visual disturbances
• Mild swelling - swelling of eyelids, face, hands, feet
• Decreased urination
• Proteinuria - high protein levels in urine

Rapidly progressive glomerulonephritis

Progresses to kidney failure over weeks to months.

Manifests as nephritic syndrome:

• Blood in the urine
• Decreased urine output
• Swelling of the face, limbs, hands, abdomen
• High blood pressure
• Blurred vision
• Nausea
• Cough with mucus that may be foamy, purplish
• Shortness of breath

Chronic glomerulonephritis

The course of the disease is slow.

Chronic nephrotic syndrome is manifested by:

• Blood in the urine
• Proteinuria - increased protein excretion in the urine
• High blood pressure
• Swelling
• Decrease in glomerular filtration rate
• Renal insufficiency

The basis of the examination is to obtain a history of a previous urinary tract infection, determine the swelling, information about urine and urination, measure blood pressure.

Blood sampling

Blood is taken for biochemical examination. Urea, creatinine levels are monitored to indicate an ongoing problem in the kidneys. Mineralogram is also monitored, especially potassium, total protein, albumin, uric acid levels, etc.

Taking blood for immunological examination - examination of immunoglobulins in the blood (in glomerulonephritis).

From the blood count, anemia and an increased number of leukocytes are observed, which indicate ongoing inflammation in the body.

At high temperatures, a hemoculture is taken to detect the presence of bacteria in the blood.

Urinalysis

The most important investigative method is the examination of the urine, its quantity, colour, odour, turbidity, specific gravity and examination of the urinary sediment.

A urine sample is collected for culture. A sterile midstream urine is sent for culture.

Functional tests include:

Creatinine clearance - collecting urine over 12 or 24 hours and drawing blood. This examination tells about glomerular filtration rate and kidney function.

Hamburger sediment - a urine test in which urine is collected for 3 hours from 6 a.m. to 9 a.m. The amount of urine, specific gravity is measured and the presence of leukocytes, blood, and cylinders in the urine is analyzed.

Quantitative proteinuria - collection of urine over a 24 hour period to determine the total amount of protein in the urine over a 24 hour period.

Other examination methods

• Ultrasound examination to detect upper urinary tract obstruction and renal edema
• X-ray examination. Excretory urography and cystography, which is performed after urination
• Static scintigraphy (to check for inflammation in the kidney), isotope micturition cystography (if vesicoureteral reflux is suspected)
• CT scan of the kidneys
• Urological examination
• Biopsy of the kidney

Diagnostics in childhood

Inflammation of the kidneys can occur in children, especially in newborns and young children. Children often cannot tell what is hurting and troubling them.

The pediatrician's goal is to prevent kidney damage due to inflammation.

The urine in diapered children is collected in a collection bag and sent for culture.

The pediatrician follows the established method of Jodal's criteria.

The likelihood of acute pyelonephritis is when the child has:

• Temperature higher than 38.5 °C
• FW - blood sedimentation is greater than 25 mm in the first hour
• Leukocytosis is present - an increased number of leukocytes in the blood
• Elevated CRP (inflammatory parameters) values
• Urinalysis: cylinders of leukocytes are present in the urine

Tubulointerstitial nephritis often manifests as acute inflammation with renal failure. Sometimes it is asymptomatic and only detected when urine is collected for examination.

Acute pyelonephritis

Infection in the kidney spreads from the renal pelvis to the cortex. The pelvis, calyx and marrow of the kidney are first affected by inflammation and infiltration by white blood cells.

The course is sudden within a few hours to a day.

The person seeks medical attention for temperature output and dull pain in one or both sides of the sacral area.

Glomerulonephritis

According to the time course, it is divided into:

• Acute glomerulonephritis - It has a sudden onset and within a few days there is a decline in kidney function. With treatment, kidney function corrects within a few weeks.
• Subacute glomerulonephritis - Rapidly progressive, renal failure occurs if treatment is incorrect or delayed.
• Chronic glomerulonephritis - Develops slowly over years and causes renal insufficiency.

Kidney inflammation in pregnancy

Urinary tract and kidney disease can complicate the course of pregnancy.

The kidneys are more stressed during pregnancy and have to filter more blood.

The first signs of urinary tract inflammation are manifested by frequent urination or pain or burning when urinating. They should not be ignored, as the infection can spread further to the kidneys.

Inflammation most commonly affects the right kidney and is manifested by pain in the sides of the lower back.

In some cases, it may be an asymptomatic course of kidney inflammation. In this case, it is very difficult to recognize the inflammation. Untreated inflammation can cause premature birth, especially in the third trimester.

Conversely, in the early stages of pregnancy, there is also a risk of miscarriage due to the disease.

Treatment takes the form of hospitalisation and the administration of antibiotics directly into the vein, especially in the early days. Antibiotics suitable during pregnancy are administered so as not to endanger the development of the foetus.