Assessment of kidney function

This filtrate then flows along the length of the nephron, which is a tubular structure lined by a single layer of specialized cells and surrounded by capillaries.

This is performed at the microscopic level by many hundreds of thousands of filtration units called renal corpuscles, each of which is composed of a glomerulus and a Bowman's capsule.

They may develop evidence of chronic kidney disease, that can be used to assess its severity, for example high blood pressure, osteoporosis or anaemia.

[2] Central to the physiologic maintenance of GFR is the differential basal tone of the afferent and efferent arterioles (see diagram).

In other words, the filtration rate is dependent on the difference between the higher blood pressure created by vasoconstriction of the input or afferent arteriole versus the lower blood pressure created by lesser vasoconstriction of the output or efferent arteriole.

GFR is equal to the renal clearance ratio when any solute is freely filtered and is neither reabsorbed nor secreted by the kidneys.

[citation needed] There are several different techniques used to calculate or estimate the glomerular filtration rate (GFR or eGFR).

The normal range of GFR, adjusted for body surface area, is 100–130 average 125 (mL/min)/(1.73 m2) in men and 90–120 (mL/min)/(1.73 m2) in women younger than the age of 40.

The most important items in a physical examination are signs of vasculitis, lupus erythematosus, diabetes, endocarditis and hypertension.

[citation needed] Risk factors for kidney disease include diabetes, high blood pressure, family history, older age, ethnic group and smoking.

But significant decline of the GFR from a previous test result can be an early indicator of kidney disease requiring medical intervention.

The sooner kidney dysfunction is diagnosed and treated the greater odds of preserving remaining nephrons, and preventing the need for dialysis.

Not all clinicians agree with the above classification, suggesting that it may mislabel patients with mildly reduced kidney function, especially the elderly, as having a disease.