The hidden system of tiny veins in the kidney: Let's simply learn about the Peritubular Capillaries

We all know that the kidneys are the filters in our body. Just like the oil filter in a car, these two kidneys do a great job of cleaning our blood and removing unnecessary waste products as urine. But have you heard about the tiny heroes behind this big job, the ones you can't even see? Those heroes are what we call `Peritubular Capillaries`. Although the name may sound a bit complicated, the work they do is very simple and essential. Today, let's talk about this tiny system of veins.

Simply put, what are these peritubular capillaries?

Okay, let's break this name down.

• Peri means "around".
• Tubular means "small channels".
• Capillaries are the finest blood vessels in our body.

So, to put it simply, peritubular capillaries are a network of very fine blood vessels that wrap around the small channels inside our kidneys. Imagine that the kidney is a big city. There are about a million tiny houses in that city. We call these houses nephrons . These nephrons are the units that actually filter and clean the blood. So, the network of small byways that wrap around each of these houses (around the nephron channels) is called the peritubular capillaries. It is through these byways that the necessary goods (nutrition) are brought to the houses and the garbage (waste) that accumulates in the houses is taken away.

What are the two main things that happen in this small vascular system?

This network of tiny blood vessels is like a clever accountant. It carefully selects and separates what the body needs and what it doesn't. This work can be divided into two main parts.

1. Secretion: After the initial filtration process in the kidneys, any remaining waste products in the blood are secreted from these veins into the renal tubules. These waste products are then excreted in the urine.

2. Reabsorption of nutrients: When the kidneys filter blood, sometimes some of the good things that the body needs are also filtered out. Think of it like when you filter a cup of tea, some sugar gets caught in the filter along with the tea leaves. At such times, these peritubular capillaries recognize those nutrients and reabsorb them into the blood.

Let's look at this table to see how important these two processes are.

What happens if these capillaries are damaged?

This is where we need to be very concerned. When these delicate blood vessels start to become damaged, they can't do their job properly. We call this condition peritubular capillary rarefaction . This means that the density of these vessels decreases, they become thinner, and they are destroyed.

The most dangerous thing about this is that once these channels are damaged, they have very little chance of recovering.

This damage can lead to two main medical conditions:

1. Chronic Kidney Disease (CKD): When the capillaries fail to function, the kidneys' filtration process gradually becomes impaired. Over time, this can progress to chronic kidney disease, which can eventually lead to kidney failure.

2. Hypertension: The kidneys control the amount of salt and water in the body. When these capillaries are damaged, this control is lost. As a result, blood pressure starts to rise. Also, high blood pressure further damages these capillaries. It's like a vicious cycle.

What are the possible causes of damage to these capillaries?

• Diabetes
• Uncontrolled Hypertension
• Kidney infections
• Glomerular diseases (diseases affecting the filtering units of the kidneys)
• Ureteral obstruction

What are the symptoms that suggest a kidney problem?

Kidney disease often doesn't show any major symptoms in the early stages. But if you pay attention to your body, you can recognize some of the signs. If you have one or more of these symptoms, it's important to seek medical advice immediately .

• Flank pain on either side of the body, below the ribs.
• Fever that comes without a reason.
• Nausea and vomiting.
• Excessive fatigue in the body.
• Changes in urination pattern:
• Urinating more frequently than usual.
• Difficulty urinating.
• Blood in the urine (hematuria) .
• Burning or pain during urination (dysuria) .
• Change in urine color (turning dark brown).
• Swelling (edema), especially in the legs, ankle area.
• Recurrent urinary tract infections (UTIs).

If you have these symptoms, don't just wait and hope, "This will go away in a few days." Be sure to see your doctor and get the necessary tests done.

What are the tests that check the health of the kidneys?

Depending on your symptoms, your doctor may recommend several tests like these.

1. Kidney Function Tests:

• Urinalysis: Urine is checked for things like protein, blood, and sugar.
• Blood Tests: Blood tests measure the levels of waste products called `BUN (Blood Urea Nitrogen)` and `Creatinine` in the blood. If these are elevated, it means that the kidneys are not filtering waste products properly. A test called `eGFR (estimated Glomerular Filtration Rate)` can also give a good idea of ​​the filtration rate of the kidneys.

2. Imaging Tests:

• Kidney Ultrasound: This can check the size, shape, and presence of stones or other obstructions in the kidneys.
• CT Scan or MRI Scan: These are used if you need to examine the kidneys in more detail.

How do we protect this precious capillary system?

There's really nothing special you can do for these peritubular capillaries. All we need to do is keep our kidneys healthy. If the kidneys are healthy, this small vascular system is also healthy. Make these simple things a habit.

• Drink enough clean water throughout the day. Drinking water makes it easier for the kidneys to filter and remove waste products.
• Eat a balanced diet. Reduce foods high in salt, sugar, and fat as much as possible. Eat more fruits and vegetables.
• Control diabetes and high blood pressure. If you have these conditions, take the medication your doctor prescribes on time. Get checked regularly.
• Maintain a healthy weight for your body. Being overweight puts extra pressure on the kidneys.
• Avoid smoking completely. Smoking is a major cause of damage to blood vessels. This directly affects the peritubular capillaries.
• Do not continue to use medications such as painkillers without medical advice. Long-term use of some painkillers is harmful to the kidneys. Talk to your doctor before using any medication.

Kidney, Peritubular Capillaries, Capillaries, Kidney Disease, Chronic Kidney Disease, CKD, High Blood Pressure, Nephron, Kidney Health, Kidney health Sinhala