This article is professionally consulted by MSc, MD Lê Thị Minh Hương - Emergency Resuscitation Physician - Resuscitation - Emergency Department - Vinmec International General Hospital, Nha Trang.
Glomerulonephritis causes high blood pressure, affects the ability to cleanse blood, filter waste from the body, and causes the patient to experience generalized edema. Therefore, many people are puzzled about why glomerulonephritis causes high blood pressure and edema.
1. Symptoms of Glomerulonephritis
Glomerulonephritis is an inflammation of the small blood vessels in the kidneys, known as glomeruli. The condition can be acute (beginning suddenly) or chronic (gradually developing), and it can be fatal. When damaged, the kidneys cannot efficiently eliminate waste and excess fluid. Blood and proteins that are not filtered will be excreted in the urine.
The symptoms of glomerulonephritis can vary from patient to patient but commonly include:
• Dark brown urine due to blood and protein in the urine
• Sore throat
• Low urine output
• Lack of energy or easy fatigue
• Difficulty breathing
• Headaches
• High blood pressure
• Seizures
• Rash, mostly on the buttocks and legs
• Weight loss
• Joint pain
• Pale skin
• Edema due to fluid accumulation in the tissues.
2. Why does glomerulonephritis cause high blood pressure?
2.1. The connection between the kidneys and blood pressure
The kidneys receive about 25% of the blood flow from the heart, so any abnormal changes in the kidneys or blood pressure affect each other.
High blood pressure directly damages the kidneys, even to the point of irreversible damage. Mild manifestations include microscopic protein in the urine (albuminuria), while more severe cases can lead to renal arteriosclerosis. When high blood pressure occurs, the filtration membrane of the kidneys is damaged, allowing larger molecules (like proteins) to pass through.
In individuals with long-term high blood pressure, the renal arteries can be affected, gradually causing sclerosis and narrowing. The higher the blood pressure, the more severe the complications in the kidneys. Ultimately, the consequence of high blood pressure affecting the kidneys is chronic kidney failure, and the only treatment option becomes kidney transplantation.
Not only does high blood pressure cause kidney problems, but conversely, even minor kidney function changes can impact blood pressure. For example, renal artery stenosis is a leading cause of both primary and secondary hypertension caused by kidney disease. Additionally, in the treatment of diseases such as acute and chronic glomerulonephritis, nephrotic syndrome, and kidney failure, blood pressure control is essential.
2.2. Glomerulonephritis causes high blood pressure
According to many reports, high blood pressure complications in glomerulonephritis are prevalent, affecting about 50-54% of patients. More than half of glomerulonephritis patients experience high blood pressure symptoms, which are often challenging to treat and manage.
Regarding the mechanism behind why glomerulonephritis causes high blood pressure, doctors suggest that hypertension obstructs the “outgoing arteries” in the kidneys, causing changes in kidney size and swelling of the glomerular capillaries. This narrowing activates the juxtaglomerular apparatus, leading to increased blood pressure, and in some cases, malignant hypertension may occur.
Patients with diabetic kidney disease have high glucose levels, which increases the blood flow to the kidneys, increasing pressure on the filtration process and raising blood pressure. Therefore, patients should manage their blood sugar levels through a balanced, nutritious diet and maintain stable blood pressure through medication. This can help prevent kidney complications, including glomerulonephritis.
In summary, high blood pressure can damage the kidneys and prevent them from functioning normally. Simultaneously, the kidneys play a crucial role in regulating blood pressure. Glomerulonephritis causes high blood pressure due to kidney dysfunction.
3. Why does glomerulonephritis cause edema?
3.1. Characteristics
Edema is the most prominent symptom in patients with acute glomerulonephritis, which begins suddenly and progresses throughout the body, impacting daily activities and even threatening life.
Edema is the first clinical sign that patients notice before seeking medical examination. Initially, the body seems to swell despite not consuming excess food, such as when shoes, rings, or waistbands become tight, or when the abdomen becomes distended and bloated. This weight gain causes fatigue, difficulty breathing, and puffiness in the eyelids upon waking.
Edema commonly appears in the lower limbs, thickening the dorsum of the feet and gradually spreading to the ankles, lower legs, knees, and groin. The skin appears taut and shiny, with no visible bones or ankles, and when pressed, it feels soft and depressed, showing signs of pitting edema. In bedridden patients, the edema concentrates in the back, buttocks, neck, and may lead to pressure sores. The genital tissues are also swollen, with the scrotum in men and the labia and vulva in women becoming enlarged and fluid-filled.
3.2. Mechanism
So why does glomerulonephritis cause edema? The kidneys have the responsibility of filtering toxins and waste products from metabolic processes and removing them through urine. When the filtration membrane is damaged by glomerulonephritis, large molecules can leak out, causing a significant decrease in blood protein levels. As a result, the colloid pressure in the blood vessels, which is created by proteins, is no longer maintained. Hydrostatic pressure, which helps to push blood through vessels, increases due to the effects of high blood pressure.
When the difference between hydrostatic and colloid pressures becomes too large, the fluid cannot stay within the blood vessels and escapes into the interstitial tissue. This phenomenon explains why glomerulonephritis causes generalized edema, as well as pleural effusion, pericardial effusion, and ascites.
3.3. The danger
Acute glomerulonephritis leads to many dangerous complications, mostly due to edema. For example:
Excessive fluid accumulation in the interstitial tissue leads to generalized edema, making it difficult to move.
When fluid accumulates in the pericardium or pleura in large volumes, it compresses the heart chambers, causes lung collapse, and compresses the circulatory system. This results in hypotension, respiratory failure, and death.
When circulatory volume is inadequate, the organs do not receive sufficient blood supply. The brain becomes deprived of oxygen, causing altered consciousness, confusion, stupor, and even coma.
Reduced renal perfusion worsens kidney failure, causing toxin buildup in the blood and affecting other organs' functions.
Protein loss in the urine leads to a decrease in blood proteins, causing malnutrition. The immune system weakens, making patients more susceptible to infections in the respiratory and digestive systems.
Blood clotting systems are affected, increasing the risk of thrombosis and embolism.
Ultimately, glomerulonephritis can lead to nephrotic syndrome, where patients lose large amounts of protein in the urine. This causes the body to retain more fluid and salt, leading to high blood pressure, increased cholesterol, and generalized edema. If not controlled and treated with corticosteroids, nephrotic syndrome can progress to end-stage kidney disease when kidney function is almost entirely lost.
Glomerulonephritis can cause high blood pressure and edema, severely impacting the patient’s health. Therefore, when unusual signs are observed, patients should visit medical centers for examination and timely treatment to minimize the risk of complications.
References: medicalnewstoday.com, webmd.com, healthline.com
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