Renal Function and Pathophysiology

After going through the three things that the kidneys filter, we’ll head on to what the kidneys produce that helps in creating red blood cells within the bone marrow. We’ll also tackle some of the kidneys’ main functions, with a bit of pathophysiology.

Let’s start.

Kidney Malfunction

If the kidneys are not working properly or are malfunctioning, there are a couple of components that will immediately get affected, mainly:

  • Hydrogen ions
  • Urea nitrogen (BUN)
  • Creatinine

These three components with an acronym, HUC, are expected to increase dramatically. Aside from these elements, hemoglobin and hematocrit levels will then decrease due to the inability of the kidneys to create erythropoietin.

Erythropoietin Defined

Erythropoietin is the hormone responsible for initiating the creation of red blood cells inside the bone marrow.

As nurses caring for clients who have renal failure and is undergoing peritoneal dialysis or hemodialysis, you have to anticipate that hydrogen ions, blood urea nitrogen, and creatinine are relatively high. The kidneys, due to its condition, are unable to get rid of these elements because urine is not coming out of the body.

High Blood Pressure

When a client with kidney disorder has increased blood pressure, it’s difficult to get rid of the fluid from the body to lessen the pressure. For this reason, hemodialysis is done.

Aside from hemodialysis, the client needs to be on fluid restriction because the fluid will stay inside the body and will not be eliminated immediately.

Understanding Kidney Structure

To know the primary function of kidneys, we must first go through its physiology.

As the filtering system of the body, you can consider the kidneys as washer machines. This washer machine filters the blood and gets rid of toxins and wastes that are excreted from the body in the form of urine. The nephrons are the basic working unit of the kidneys that do the filtering.

Filtering is done with the presence of glomeruli found inside the nephrons. These glomeruli branch out to the ends of the nephrons and are somewhat similar with an apple tree or bouquet of flowers.

Glomerular Filtration Rate

Blood goes through the nephrons and enters the glomeruli where they will be filtered. This process is called the glomerular filtration rate (GFR). Remember, the normal filtration rate is between 85 ml/min to 105 ml/min which translates to a healthy kidney that’s constantly working to filter hydrogen, urea nitrogen, and creatinine.

Inside the hospital, the bare minimum is around 65 ml/min.

The Geriatric Community

When geriatric clients reach the ages of 65 – 70, they tend to lose 3% of functioning nephrons yearly. Therefore, by the time they reach the age of 85, retention of proper kidney function will only be at 50%. This is the reason why the geriatric community experiences chronic health issues related to the heart, skin, and even the eyes.

Hyperglycemia and Hypertension

Hyperglycemia due to diabetes and hypertension are factors that precipitate kidney malfunction or breakdown.  

With hyperglycemia, the blood becomes thick and syrupy, like mud. If this mud-like consistency is pushed inside the kidneys and into the nephrons, there is an increased possibility that the kidneys (washer machines) will eventually malfunction.

Chronic hypertension, on the other hand, causes a consistent and long-term heightened pressure that affects the kidneys which can also lead to acute kidney failure.

In our next lecture, we’ll tackle the causes of acute kidney injury which leads a client to go into acute renal failure instantly.