How To Calculate The Glomerular Filtration Rate

2018-09-26 08:33

To all kidney patients they must accept some tests to verify their kidney condition,the Glomerular filtration rate can represent their kidney function,then i will show you the detailed information about Glomerular filtration function test as following:

C=UV/P

C – clearance rate ( ml / min )

V – urine volume per minute ( ml / min )

U – Urine Determination of Substance Concentration ( mmol / L )

P – The concentration ( mmol / L ) of the substance determined in blood

Because the clearance value calculated by this formula is the result of the individual subject, but the individual size, height, weight, age and so on vary greatly and must be standardized with a standard body surface area of 1.78 m2 correction. A represents the body surface area of an individual.

The corrected clearance value c = UV / p× 1.73 / a

Calculation of body surface area:

LogA ( m2 ) = 0.425 log [ weight kg ] + 0.725 log [ height cm ] – 2.144

The glomerular filtration rate, renal blood flow and the reabsorption and secretion of various substances by renal tubules were measured by clearance rate ( Table 11 – 1 ).

A small part of a substance contained in plasma is filtered through the glomerulus and not reabsorbed by the renal tubules, and the rest of the blood can be secreted by the renal tubules, so that the substance is almost completely discharged after passing through the kidney.Then its clearance rate not only represents renal plasma flow ( RPF ), but also reflects the secretory function of renal tubules, such as aminohippuric acid, iodinate, phenol red and penicillin.

If another substance can be completely filtered through the glomerulus and the renal tubules do not absorb or excrete it, its clearance rate can reflect the glomerular filtration rate.GFR ), such as insulin, creatinine, etc.

A substance is completely reabsorbed by renal tubules after glomerular filtration, and its clearance value is equal to 0, such as glucose. When the plasma concentration approaches the renal glucose threshold, the maximum reabsorption of renal tubular glucose ( TMG ) in the filtrate can be calculated by using the clearance formula.Toreflect the reabsorption function of proximal renal tubules.