What is cystatin C?
Cystatin C is a protein that is produced throughout the body. A cystatin C test is used to help evaluate kidney function, and it plays many other roles in health, including its role in predicting new-onset diabetes or deteriorating cardiovascular disease.
Unlike creatinine, cystatin C is not significantly affected by muscle mass (hence, neither sex nor age), race, or diet.
Why test cystatin C?
You can test cystatin C to discover your risk factors for lifestyle diseases, if you drink a lot of alcohol, or eat a diet low in nutrient-rich foods such as fruits, vegetables, nuts, seeds, and beans, or to monitor changes to your blood values as you make lifestyle changes, or take supplements or medication.
Low
You have a lower level of cystatin C than expected in your bloodstream.
What causes low cystatin C?
Low cystatin C is rare and should be discussed with your doctor.
Symptoms of low cystatin C
Low cystatin C levels are uncommon and typically do not cause specific symptoms. However, they can sometimes be associated with conditions involving rapid muscle loss or malnutrition, which might lead to general symptoms like muscle weakness, fatigue, and unintended weight loss. In such cases, it's important to investigate the underlying cause to ensure proper nutritional and medical support.
What causes high cystatin C?
A high level of cystatin C in the blood corresponds to a decreased glomerular filtration rate (GFR) and is associated with kidney dysfunction. Cystatin C should remain steady in the blood if the kidneys are working efficiently and the GFR is normal.
An imbalance of cystatin C can also occur with normal aging, due to unhealthy lifestyle factors or some chronic diseases. People with osteoporosis have elevated cystatin C, as do those with hyperthyroidism and diabetes. Recent studies suggest that increased levels of cystatin C may also be associated with an increased risk of heart disease, heart failure, and mortality. Scientists are still trying to understand the relationship between cystatin C and these conditions.
If both your cystatin C and your hsCRP are high, this might indicate inflammation. If you want to rule out systemic inflammation, we recommend testing other inflammatory markers such as ESR, TNF alpha, IL-6, fibrinogen and homocysteine (preferably with folate and B).
Symptoms of high cystatin C
High cystatin C levels often indicate impaired kidney function and can be associated with symptoms of kidney disease. These symptoms might include reduced urine output, fluid retention leading to swelling in the legs and ankles, and fatigue. Other signs can include high blood pressure, nausea, and shortness of breath due to the buildup of waste products in the blood. High cystatin C levels can signal the need for further evaluation and management of potential kidney issues to prevent further damage.
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Preparations for this test
No preparation is needed for this test.
On the day of the test
Always take I.D. with you when going to take a test. Arrive early and sit down quietly for 15 minutes before taking the test.