Cystatin C test is a vital test for assessing kidney function, in case of suspected kidney problems and if other kidney function tests are not dependable. Cystatin C is a protein that is made by the cells in the human body. When the kidneys are functioning well, they maintain the level of cystatin C in the blood. If the level of cystatin C is higher in the blood, it indicates that the kidneys are not working properly.

Read on to know how cystatin C levels can impact your overall health status.
Cystatin C - Test

What is cystatin C?

Cystatin C is a protein molecule that impedes the breakdown of other proteins, this is produced by most cells in the body and found in all bodily fluids. Cystatin C is involved in several important roles in the body including:

  • Growth and development
  • Bone metabolism
  • Safeguards the brain against injury
  • Lowers risk of neurodegenerative diseases

Cystatin C is completely broken down in the kidneys almost 99%. However, in healthy people, the production and breakdown of cystatin C occur at a relatively constant rate. In case, the kidneys are not functioning well, this protein gets accumulated in the blood and indicates that the kidneys are not working.

As the kidney function is closely connected with the functioning of other vital organs in the system, studies reveal that higher cystatin may forecast a higher probability of heart disease, cognitive dysfunction, and other cause of mortality. While medical experts have also found that lower levels may be linked to an increased risk of Alzheimer’s and aneurysms

Purpose of the test

This test can be used as an alternative to creatinine and creatinine clearance to evaluate for and monitor kidney dysfunction in people with known or suspected kidney disorders. It is most valuable in special situations where creatinine levels could be misleading.

Cystatin C blood test can help the doctor find out the glomerular filtration rate (GFR) and the GFR number aids the physician to know how well the kidneys are functioning.

High Cystatin C

Higher levels of cystatin C mean that kidney function is mostly decreased. Some of the causes that are usually associated with high cystatin C include:

  • Impaired kidney function due to several diseases
  • Drugs like chemotherapeutics
  • Other factors that can marginally increase cystatin C levels include:
  • Chronic inflammation
  • Obesity
  • Physical inactivity
  • Smoking
  • Alcohol
  • Hyperthyroidism
  • Growth hormone excess
  • Some types of cancer
  • Certain medications such as corticosteroids, fenofibrate (but not other fibrates), and chemotherapeutics
  • Third trimester in pregnancy and twin pregnancies
  • Genetics
  • Ageing

High Cystatin C levels in Disease conditions such as

  • High blood pressure
  • Metabolic syndrome
  • Pre-diabetes and diabetes
  • Atherosclerosis
  • Heart disease
  • A decline in cognitive function, dementia, and Alzheimer’s
  • Depression
  • Lower bone mineral density, osteoporosis, and fractures
  • Preeclampsia in pregnancy
  • Cardiac disease-related mortality

Cystatin C Test Normal Range

The normal range of cystatin C is 0.62 -1.15 mg/L.

Advantages And Disadvantages Of The Cystatin C Test

Pros of the test

Cystatin C can be used as alternative blood work for blood creatinine. The levels of cystatin C do not depend on muscle mass, physical activity, or protein intake. Thus, it is highly beneficial in people who had lost muscle mass like older people and those with chronic disease conditions.

It can also help find out even mild reduction in kidney function, known as preclinical kidney dysfunction. Where creatinine, on the other hand, doesn’t elevate until 50% of kidney function is impaired. The level increases more than creatinine and hence it can find out any kidney injury at an earlier stage.

Cons Of The Test

Some of the factors that can affect cystatin C level regardless of the kidney function:

  • Inflammation
  • Thyroid disorders
  • Corticosteroid medication
  • Cancer
  • Chemotherapy
  • Ageing

When To Get Tested?

Your physician may suspect that you may have a reduced kidney function, however, serum creatinine levels are not reliable, then he orders cystatin C to be taken at regular intervals when a person is known to have kidney dysfunction.


The blood sample is collected from a vein in the arm.

Test Preparation

No specific preparation is needed

What Does The Test Result Mean?

A high level of cystatin C in the blood indicates a decreased glomerular filtration rate (GFR) and kidney dysfunction.

As this protein molecule is made throughout the body at a regular rate and removed and broken down by the kidneys. It should remain at a steady level in the blood if the kidneys are working well,

Latest research has also revealed that increased levels of cystatin C may also suggest a higher risk of heart disease, heart failure, and mortality.