Question

Serum cystatin C as a marker of kidney function , its role in diagnosis , prognosis , and detection of renal impairments , in addition include in you reports the pros and cons of cystatin C as a marker of kidney function

Answer 1

There are many biomarkers available that can be used for checking kidney function like GFR(Glomerular filtration rate) which is a marker of kidney health or Creatinine which is a widely used biomarker for kidney function but it is generally inaccurate in detecting mild renal failures. Likewise, cystatin C is a low molecular weight biomarker to detect the proper functioning of the kidney. If kidney function and glomerular filtration decline, the cystatin C rise in the blood.

Generally, GFR and Creatinine are used as biomarkers for the detection of renal impairments. however, creatinine which is dependent on GFR its concentration also depends on age, gender, muscle mass, race, medication, and dietary meat intake. Secondly, Creatinine is not absorbed by the renal tubules but it is secreted. Other limitations with Creatinine are timely urine collection for detection of renal impairments which is the cause for errors.

So, instead of using Creatinine as a marker of GFR, cystatin C is used as a marker of GFR because it is a low molecular weight single-chain non-glycosylated protein produced by all nucleated cells at a constant rate. Secondly, it is not secreted by it is reabsorbed and catabolized by the proximal tubule cells. These characteristics make cystatin C an ideal endogenous marker for GFR. It is also not affected by age, gender, muscle mass, race, medication, and dietary meat intake. Thus, serum cystatin C is a more sensitive marker of GFR than Creatinine.

Creatinine usually fails to detect the decline in GFR at an early stage of renal impairments as its level only begin to rise when approximately 50% of the renal functioning is lost. In such cases, cystatin C is better in the detection of GFR at the early stages which has been proved in various type 2 diabetic patients studies. There has been no cons reported for cystatin C as such.