What is Chronic Renal Failure? - Causes & Symptoms

What is Chronic Renal Failure? - Causes & Symptoms
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  • 1:08 The Causes of CKD
  • 1:58 Electrolyte,…
  • 4:55 Secondary Problems
  • 7:16 What Is Uremia?
  • 7:47 Treatment of CKD
  • 8:24 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov
This lesson will discuss chronic kidney disease, or chronic renal failure, as it was once more commonly called. We will have an overview of what it means and what it does to your body.

A Long-Term Problem

As a person ages they move a little bit slower, remember things less and less, and can see and hear a bit worse. This is because, over the long term, overuse or improper care of our joints or hearing can lead to some serious damage.

Comparably, all sorts of things can hurt our kidneys and over a long period of time may lead to their dysfunction.

Chronic Renal Failure

Chronic renal failure (CRF), for our purposes, is the historical term that is synonymous with chronic kidney disease (CKD), which is the gradual loss of kidney function over many months or years.

The function of the kidneys is to filter out toxins and waste from your blood. In a very real sense, the kidneys are exactly like a water treatment plant your city may have, except they are a blood treatment plant for your body.

The kidneys also serve to reabsorb important substances initially filtered out so that you don't get dehydrated and don't lose important electrolytes like calcium important for bone and muscle health and function.

The Causes of CKD

Just like I implied in the introduction, things like loud rock concerts can hurt our hearing in the long run, or diseases and infection can break apart our joints. In the long run, this can result in complete hearing loss and arthritis, respectively. Well, there are regrettably many things that over the long run will damage the kidney's function, such as its capacity to filter blood. These things include:

  • Diabetes
  • Hypertension
  • Glomerulonephritis
  • Pyelonephritis, or kidney infection
  • Obstruction of the urinary tract due to a stone
  • Genetic defects, leading to conditions such as polycystic kidney disease

And many other kidney-specific diseases, such as tubulointerstitial disease.

Electrolyte, Acid/Base, & Water Status

CKD, regardless of cause, has five different stages. The first stage implies the kidneys have a normal glomerular filtration rate (GFR), the rate at which blood is filtered by the kidneys. By stage five, kidney function is extremely low (less than 15% of normal capacity), and we term this end-stage renal disease.

Normally, we really don't begin to see many serious clinical signs or symptoms associated with CKD until about 75% of total kidney function, between the two kidneys, is lost due to chronic disease. This means that people in stages 1-3 are usually asymptomatic.

This process kind of reminds me of a deflating tire with a tiny hole. As this tire deflates over a long period of time, it can still function basically normally up to a certain point, but after that point it is so deflated that you can't drive your car anymore.

Anyways, let's examine what happens in CKD as this kidney function decreases. First as the GFR decreases, the kidneys cannot filter out waste substances, such as blood urea nitrogen and creatinine. The increase of these substances in the blood is termed azotemia.

Furthermore, as kidney function declines, the levels of electrolytes, such as sodium, chloride, hydrogen, potassium, and phosphate rise in the blood. That's because normal healthy kidneys can regulate their excretion out of the body as necessary, but chronically sick kidneys cannot.

You should be aware that the increase in the levels of acidic hydrogen ions leads to a dangerous condition known as metabolic acidosis, whereas the increased levels of sodium lead to the subsequent retention of water in the blood. This leads to hypertension or high blood pressure, which may actually exacerbate the failure of the kidneys.

Note how nowhere did I mention that the levels of calcium in the blood increase in a person with late stages of chronic kidney disease. That's because people with advanced stages of chronic kidney disease experience hypocalcemia, or low levels of calcium in the blood. This sounds really odd since we as people like to box things into neat categories. I mean, if all the other electrolytes increase in the body, then why not calcium? Well, physiology doesn't lend itself to neat and orderly groups. That's why it's such a difficult topic to study.

Secondary Problems

In chronic kidney disease, the kidneys lose functional mass. Meaning, the normal functional architecture of the kidneys (the nephrons and interstitium) is replaced by scar tissue due to any of the disease processes we talked about before.

This scar tissue is completely non-functional and useless. It's literally as useful as tying ropes over a deflating tire. What good is that going to do to save the tire from deflating?

The scar tissues also cause a kidney to look shriveled and smaller than normal when viewed under ultrasound examination, just like ropes tied tightly over something can compress it to a smaller size.

Because the kidneys lose functional mass, they not only lose the ability to filter blood but the important ability to activate vitamin D. As active vitamin D levels in the body decrease, calcium can't be absorbed from the gut, resulting in hypocalcemia.

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