What causes low glomerular filtration rate?

As we all know, kidneys play an important role in the human body and can remove harmful substances from the human blood. However, the transmission of harmful substances in the kidneys mainly depends on the operation of glomeruli, which play a filtering role. The amount of harmful substances filtered out by glomeruli in a certain period of time is called the filtration rate. It is an effective indicator for examining kidney organs in hospitals. Once the glomerular filtration rate indicator is abnormal, it will cause many complications in the human body and bring harm to the human body.

A low glomerular filtration rate refers to the amount of ultrafiltrate produced by both kidneys per unit time (per minute), which is called the glomerular filtration rate. It is one of the important indicators to measure renal function.

Glomerular filtration mechanism

Glomerular filtration is achieved through two functions: one is the glomerular mechanical barrier function, and the other is the glomerular charge barrier function. Mechanical barrier function refers to the ability of the glomerulus to filter out small molecules but not large molecules. This ability allows large molecules in the blood to remain in the blood and small molecules to be sent to the urine. Since most blood toxins are small molecules, they are usually excreted into the urine. The so-called charge barrier refers to the ability of the glomerulus to allow positively charged substances to pass through, ensuring that negatively charged substances remain in the blood. Through the above two functions, the glomerulus ensures that small molecules with positive charge in the blood enter the urine during the filtration process. When the urine flows through the renal tubules, the renal tubules reabsorb some of the beneficial components in the urine into the blood through their own reabsorption ability, and excrete the harmful parts of the urine out of the body.

Clinical significance

1. Increased glomerular filtration rate can be seen in

(1) In the early stages of diabetic glomerulosclerosis, the increased secretion of growth hormone causes glomerular hypertrophy and an increase in glomerular filtration rate.

(2) In some cases of minimal change nephrotic syndrome, the glomerular capillary colloidal osmotic pressure is reduced and the glomerular lesions are mild, so the filtration rate increases.

(3) The glomerular filtration rate may increase during pregnancy and return to normal after delivery.

2. Decreased glomerular filtration rate can be seen in

(1) Various primary and secondary kidney diseases that affect glomerular filtration function.

(2) As people age, the glomerular filtration rate gradually decreases. After the age of 40, the glomerular filtration rate decreases by 1.15 ml/min each year.

Normal reference value

For men it is (125 ± 15) ml/min; for women it is about 10% lower.