Cystatin C | Laboratory research

General Information

Cystatin С is a low molecular weight protein that belongs to the group of cysteine-proteinase inhibitors and participates in the intracellular catabolism of proteins.

Cystatin synthesis is carried out in all nucleated cells throughout life

Due to its low molecular weight and positive electrical charge, cystatin C is easily filtered by the renal glomeruli and reabsorbed by the proximal tubules. Therefore, under normal functioning of the proximal tubules, it is not present in the urine.

According to these characteristics, cystatin C is an endogenous marker of glomerular filtration rate. The correlation is inversely proportional: an increased amount of cystatin in the urine indicates a lower level of glomerular filtration.

According to studies, cystatin C is a better marker for assessing the functional state of the kidneys than creatinine.

When is the survey conducted?

• Moderately decreased glomerular filtration (80 and 40 ml/min)
• Patients with acute renal failure taking medications/drugs
• Elderly, children, pregnant women with suspicion of preeclampsia, diabetes, muscle diseases, kidney transplant.

There is an opinion that cystatin C may be an informative marker in acute heart failure.

advance preparation - It is better to conduct the research on an empty stomach

Research material – Venous blood

Referral norms

0-3 days - there is no norm

4-5 days – 1,22 – 1,68

6 days - 1 month - 1,37 - 1,89

1 month – 1 year – 0,73 – 1,17

1 year - 19 years - 0,60 - 0,84

19 years - 49 years 0,53 - 0,92

49 years - 99 years - 0,58 - 1,02

Interpretation of results

An increase in cystatin C indicates insufficient glomerular filtration.

Due to the immaturity of the glomerular system of newborns, an increase in the serum cystatin level is observed in infants up to 3 months of age.

Corticosteroids inhibit the synthesis of cystatin in cells, which can be the reason for the inappropriate interpretation of laboratory values.