The kidneys are one of the body’s most essential organs that must help regulate in order to function properly.
The kidneys have three primary functions: to screen and cleanse the bloodstream, to keep and control a proper fluid and biochemical balance inside the body, and to produce urine as a by-product of their activities.
Each activity is intertwined with the others, not only because they all involve introducing or eliminating substances and fluids from the circulation but also because they all take place in the kidney’s glomeruli.
The terminologies, i.e. glomerular filtration rate and renal plasma flow, are both related to the renal pathway, and the processes overlap each other throughout the filtration procedure performed by the kidneys.
This article will help you understand what they mean and how both the terms are different and essential for each other.
Key Takeaways
- Glomerular Filtration Rate (GFR) measures the rate at which blood passes through the glomerular filter of the kidneys. In contrast, Renal Plasma Flow (RPF) measures the volume of plasma that passes through the kidneys per unit of time.
- GFR is a better indicator of overall kidney function than RPF, which is more specific to the blood flow within the kidneys.
- Abnormalities in GFR can indicate kidney damage or disease, while abnormalities in RPF can indicate changes in blood flow to the kidneys.
Glomerular Filtration Rate vs Renal Plasma Flow
The difference between glomerular filtration rate and renal plasma flow is that the pace at which soluble chemicals and moisture are squeezed out of the bloodstream, going to the two kidneys, is known as the glomerular filtration rate, whereas renal plasma flow is a measurement of the frequency during which plasma flows through the kidneys. Renal plasma flow can be calculated using the RBF or Renal blood flow unit, as these measurement gauges are closely related.
GFR (glomerular filtration rate) is the sum of the drainage rates of the kidney’s functional glomeruli. GFR is the best technique to evaluate renal function, and when combined with proteinuria, it may assist in identifying the severity of CKD in a person.
The GFR concentration and the degree of change over time.
The glomerular filtration rate is among the indicators of renal dysfunction (GFR). The flow velocity of the glomerular filtrate via the kidney is referred to as the glomerular filtration rate.
The amount of blood serum cleared of creatinine per unit time interval is the creatinine clearance rate CCR, which is a helpful metric for estimating GFR.
Renal plasma flow (RPF) is the accumulation of fluid plasma supplied to the kidneys in unit time in renal mechanics. In humans, the kidneys get around 25% of blood pressure, which amounts to 1.2-1.3 L/min in a 69 to 70-kg adult male.
It reaches the brain in around 94 percent of cases. RBF and renal plasma flow (RPF), which would be the amount of blood plasma supplied to the renal per time interval, are intimately associated.
Comparison Table
| Parameters of Comparison | Glomerular Filtration Rate | Renal Plasma Flow |
|---|---|---|
| Meaning | GFR (glomerular filtration rate) is the sum of the drainage rates of the kidney’s functional glomeruli. | Renal plasma flow (RPF) is the accumulation of fluid plasma supplied to the kidneys in unit time in renal mechanics. |
| Normal Measurement | 90 or higher in a normal adult. | 1.2 to 1.3L per minute in an adult. |
| Marker | Inulin and Creatinine | P-amino hippuric acid |
| Diseases Caused | Kidney diseases are hereditary. | Renal failures and hypertension |
| Purpose | To assess and monitor kidney functions. | To assess renal functioning and health of kidneys. |
What is Glomerular Filtration Rate?
The amount of fluid processed from the kidney (renal) glomerulus into the Bowman’s membrane per unit period is known as the glomerular filtration rate (GFR).
The variable basal tension of the afferent arterioles is crucial to the physiological regulation of GFR.
Only after considerable loss of functional nephrons is there an elevation of blood creatinine levels.
Estimating GFR utilizing formulas that include cystatin c concentrations and some or even all of the five parameters: age, height, body weight, and ethnicity, is a superior approach to quantifying renal function.
Normal GFR changes with age, gender, and body composition; in young adults, it is around 120 ml/min/1.73 m2 and declines with time in healthy people.
A reduction in GFR, on the other hand, might be a sign of diabetic nephropathy and can occur before the development of kidney failure; hence, a consistently low GFR is a particular diagnostic criterion for CKD.
GFR testing is a complex and time-consuming operation, hence why clinicians calculate GFR or eGFR using an equation. GFR estimations are critical for detecting renal illness, which has no signs until the kidneys are just about to die.
A complete blood count that analyses your creatinine levels is the most common technique to determine GFR. Creatinine is the solid waste from protein sources during digestion and regular muscular degradation.
What is Renal Plasma Flow?
Renal plasma flow has been mistaken for renal blood flow (RBF) on occasion.
Renal blood flow refers to the amount of circulation supplied to the kidney per unit of time, while renal plasma flow refers to the amount of plasma supplied to the kidney per amount of measure.
The RPF or renal plasma flow can be calculated manually if we have the renal blood flow value.
However, adequate renal plasma flow has been evaluated, which is also the quantity of plasma cleansed of the p-amino network of connected acids per time unit.
The elimination of para-amino hippuric acids (PAH) is used to quantify renal plasma flow because, at small doses, this molecule is entirely removed from the plasma by proximal tubule filtration and secretion in a single cycle.
The renal plasma flows quantitative method is derived from Fick’s law, which is a mass conservation computation. In a 69-70kg adult, the kidneys get almost 25% of cardiac output or around 1.2 to 1.3 L/min.
It reaches the brain in around 94 percent of cases. Renal blood circulation and renal plasma flow are inextricably linked.
Both words refer to the bloodstream that is supplied to the renal mechanisms in total, and both renal blood flow and renal plasma flow would be used to calculate the amount of jugular vein blood that leaves the kidneys per time interval.
Main Differences Between Glomerular Filtration Rate and Renal Plasma Flow
- The glomerular filtration rate is the rate at which the dissolved substances in the bloodstream are separated from the water and stained out, whereas renal plasma flow is the rate at which plasma (blood minus components) is supplied to each kidney.
- An average person’s normal glomerular filtration rate is 90 or higher, whereas the normal renal plasma flow rate is 1.2 to 1.3L per minute in an adult.
- The glomerular filtration rate specifically aims at the kidney’s functioning, whereas renal plasma flow signifies the renal mechanism’s health.
- The glomerular filtration rate helps in assessing the onset of chronic kidney diseases, whereas renal plasma flow helps determine renal failure and renal hypertension.
- The markers for glomerular filtration rate are inulin and creatinine, whereas the markers for renal plasma flow are p-amino hippuric acid.
- https://www.kidney.org/kidneydisease/siemens_hcp_gfr
- https://medical-dictionary.thefreedictionary.com/renal+plasma+flow
Last Updated : 11 June, 2023
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Piyush Yadav has spent the past 25 years working as a physicist in the local community. He is a physicist passionate about making science more accessible to our readers. He holds a BSc in Natural Sciences and Post Graduate Diploma in Environmental Science. You can read more about him on his bio page.
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The discussion of normal GFR and its changes with age, gender, and body composition provides valuable insight into kidney health assessment.
The article helps to understand the difference between glomerular filtration rate (GFR) and renal plasma flow (RPF) and how they are essential for kidney function.
The comparison table provided is a useful tool to understand the key differences between glomerular filtration rate and renal plasma flow.