Lab result explainedKidneyLast updated November 10, 2026

Cystatin C blood test: normal range, what a high level means and how it compares with creatinine

Cystatin C · Cystatin C with eGFR (ordered alone or alongside creatinine) · reported in mg/L (milligrams per liter); eGFRcys in mL/min/1.73 m²

Cystatin C is a small protein produced at a steady rate by every nucleated cell in the body, filtered freely by the kidneys and then broken down by the kidney tubules, so that almost none returns to the blood. Because its production is constant and its only exit is kidney filtration, the amount in the blood rises as kidney function falls, which makes it a measure of glomerular filtration rate (GFR), the same thing creatinine is used to estimate. In most adults the normal range is about 0.6 to 1.0 mg/L, with laboratory ranges running from roughly 0.5 to 1.2 mg/L depending on the assay.

Its advantage over creatinine is that it does not depend on muscle mass, diet or sex to anything like the same degree. Creatinine comes from muscle, so a very muscular person's creatinine overestimates kidney damage and a frail, elderly or amputee patient's creatinine underestimates it; cystatin C is largely free of this bias. Guidelines now recommend measuring cystatin C to confirm chronic kidney disease when the creatinine-based eGFR is borderline (45 to 59 mL/min/1.73 m²) with no protein in the urine, whenever muscle mass is unusual, and when an accurate GFR matters for drug dosing. The combined creatinine-cystatin C equation (CKD-EPI 2021) is the most accurate estimate available without a formal GFR measurement.

A high cystatin C most often means reduced kidney function, and the eGFR calculated from it (eGFRcys) is what the number is converted into. A few things raise cystatin C without any change in the kidneys, including high-dose corticosteroids, an overactive thyroid, obesity, smoking and active inflammation or cancer, and an underactive thyroid lowers it, so a result that disagrees with creatinine is interpreted with these in mind. Cystatin C also predicts cardiovascular events and death more strongly than creatinine in older adults, which is one reason it is being used more widely.

Cystatin C at a glance

  • What it is: a 13 kDa protein made by all cells at a constant rate and cleared only by kidney filtration; a marker of glomerular filtration rate that is less affected by muscle mass than creatinine.
  • Normal: about 0.6–1.0 mg/L in adults (lab ranges roughly 0.5–1.2 mg/L). Newborns run higher (often 1.5–2.5 mg/L) and fall to adult levels by about 1 year.
  • Rough guide: cystatin C 1.0 mg/L ≈ eGFR 75–85; 1.5 mg/L ≈ eGFR 45–50; 2.0 mg/L ≈ eGFR 30–35; 3.0 mg/L ≈ eGFR under 20 (for a 60-year-old; younger people read somewhat higher).
  • High cystatin C: reduced kidney function (acute or chronic), or less often corticosteroids, hyperthyroidism, obesity, smoking, inflammation or cancer with normal kidneys.
  • Low cystatin C: generally no concern; seen with hypothyroidism and in some people with high muscle mass but normal kidneys.
  • Next step: compare eGFRcys with creatinine eGFR; if both are under 60 for 3 months, that is chronic kidney disease; check urine albumin-to-creatinine ratio, blood pressure and glucose.

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What Cystatin C measures

Cystatin C is a cysteine protease inhibitor, part of the body's system for controlling enzymes that break down proteins. It is produced by all nucleated cells at a rate that varies little with age, sex, diet or muscle mass, is small enough (13 kDa) to pass freely through the glomerular filter, and is then reabsorbed and completely degraded by cells of the proximal tubule rather than being returned to the circulation or secreted. Its blood level therefore reflects how much is being filtered: when GFR halves, cystatin C roughly doubles. It also responds faster than creatinine to an acute fall in kidney function, rising 1 to 2 days earlier in acute kidney injury.

The lab measures it by an immunoassay (particle-enhanced turbidimetric or nephelometric) on a standard blood sample; no fasting is needed. Since 2010 assays have been calibrated to an international reference material (ERM-DA471/IFCC), which allows a single set of estimating equations. The eGFR is then calculated using the CKD-EPI 2012 cystatin C equation (which uses only cystatin C, age and sex) or the CKD-EPI 2021 combined creatinine-cystatin C equation, which is more accurate than either marker alone and, unlike older creatinine equations, does not include a race term. Most reports print the eGFRcys next to the raw value.

Cystatin C is not perfect. Its production rises with high-dose glucocorticoids (prednisone, dexamethasone), an overactive thyroid, higher body fat, smoking, inflammation and some cancers, and falls with an underactive thyroid, each shifting the result by roughly 10 to 25 percent independent of kidney function. When creatinine and cystatin C eGFRs differ by more than about 30 percent, clinicians look for one of these non-kidney factors on one side or a muscle-mass issue on the other. An eGFRcys much lower than eGFRcr (a ratio under 0.6 to 0.7), called 'shrunken pore syndrome', is associated with higher cardiovascular risk and is an active research area.

Normal range for Cystatin C

Reference ranges vary between labs and by age, sex and pregnancy. Use the range printed on your own report.

GroupTypical range (mg/L (milligrams per liter); eGFRcys in mL/min/1.73 m²)Notes
Adults, normalAbout 0.6–1.0 mg/L (lab ranges roughly 0.5–1.2 mg/L)Depends on the assay and calibration; use the range printed on your report. Values drift up slightly with age, by about 0.1 mg/L per decade after 50.
Newborns and infantsUp to about 1.5–2.5 mg/L in the first days, falling to adult levels by about 12 monthsReflects immature kidney filtration; pediatric labs use age-specific ranges.
eGFRcys 90 or higherCystatin C roughly 0.9 mg/L or lower in middle ageNormal kidney function (CKD stage G1 only if there is another marker of kidney damage such as albuminuria).
eGFRcys 60–89Cystatin C roughly 0.9–1.2 mg/LMildly reduced; common over 65 and not chronic kidney disease on its own without albuminuria or structural abnormality (G2).
eGFRcys 45–59Cystatin C roughly 1.2–1.5 mg/LStage G3a. This is the band where guidelines recommend cystatin C to confirm a borderline creatinine result; if eGFRcys is 60 or above with no albuminuria, chronic kidney disease is not diagnosed.
eGFRcys 30–44Cystatin C roughly 1.5–2.1 mg/LStage G3b. Moderately to severely reduced; monitoring every 3 to 6 months, medication dose review and nephrology input for most people.
eGFRcys 15–29Cystatin C roughly 2.1–3.5 mg/LStage G4. Severely reduced; nephrology care and preparation for possible kidney replacement therapy.
eGFRcys below 15Cystatin C generally above 3.5 mg/LStage G5, kidney failure. Values of 5 to 8 mg/L occur in people on dialysis.
Non-kidney shiftsUp to about 10–25 percent higher with high-dose steroids, hyperthyroidism, obesity, smoking or inflammation; about 10–20 percent lower with hypothyroidismThese do not reflect filtration and are why a discrepant creatinine result is reviewed alongside.

High cystatin C

A cystatin C above the reference range usually means the kidneys are filtering less than normal, and the eGFRcys on the same report tells you by how much. A value of 1.2 to 1.5 mg/L in a middle-aged adult corresponds to an eGFR in the 45 to 60 range, which is mild to moderate reduction; 2 mg/L corresponds to an eGFR around 30, and 3 mg/L to under 20. Because cystatin C is not affected by muscle, a high value in someone with a normal creatinine is taken seriously: it often reveals kidney disease in older, frail or low-muscle people whose creatinine has been falsely reassuring, and in these groups eGFRcys is the better guide for drug dosing.

Whether the reduction is acute or chronic is the next question. A rise over days, especially with dehydration, a new medication, infection, surgery or a contrast scan, is acute kidney injury, and cystatin C may rise before creatinine does. A stable elevation on two tests at least 3 months apart, usually with albumin in the urine, reduced kidney size on ultrasound or a known cause such as diabetes or hypertension, defines chronic kidney disease. Either way the eGFRcys is read together with the creatinine eGFR, the urine albumin-to-creatinine ratio and blood pressure, and the combined creatinine-cystatin C eGFR is used for staging.

Not every high cystatin C is kidney disease. Prednisone at 20 mg a day or more, methylprednisolone pulses and other high-dose glucocorticoids raise cystatin C production by around 10 to 30 percent; an overactive thyroid raises it, obesity and smoking add a few percent each, and active inflammation (a high CRP), HIV and some cancers increase it modestly. In these situations creatinine eGFR may be the more reliable estimate, or a measured GFR (iohexol or iothalamate clearance) can settle the question. Cystatin C in the upper normal range or mildly raised in older adults is also, independent of eGFR, a marker of higher cardiovascular risk: in a cohort of over 4,600 people aged 65 and over, those in the top fifth of cystatin C (above 1.29 mg/L) had about twice the risk of death and cardiovascular events compared with the bottom fifth.

Common causes

  1. Chronic kidney disease

    Diabetic kidney disease, hypertensive nephrosclerosis, glomerulonephritis, polycystic kidney disease and reflux nephropathy all reduce the number of working nephrons; cystatin C rises in proportion. It is particularly useful for diagnosing CKD in people over 70, where creatinine underestimates the loss of function.

  2. Acute kidney injury

    Dehydration, severe infection or sepsis, low blood pressure, obstruction of the urinary tract, contrast dye and drugs such as NSAIDs, aminoglycosides and some chemotherapy reduce filtration rapidly; cystatin C typically rises 12 to 24 hours before creatinine and falls as the kidney recovers.

  3. Heart failure and cardiorenal syndrome

    Reduced cardiac output and venous congestion lower GFR; cystatin C is raised in a large share of people with heart failure and predicts hospitalization and death more strongly than creatinine.

  4. High-dose corticosteroids

    Glucocorticoids directly increase cystatin C synthesis in a dose-dependent way. Prednisone 20 mg or more a day, high-dose inhaled or injected steroids and steroid pulses for transplant rejection or autoimmune disease can push cystatin C up 10 to 30 percent with no change in filtration.

  5. Hyperthyroidism

    Thyroid hormone increases cellular metabolism and cystatin C production; untreated Graves' disease or toxic nodules raise it by around 10 to 25 percent, and it falls back once the thyroid is controlled. Creatinine moves the opposite way, so the two eGFRs diverge.

  6. Obesity and metabolic syndrome

    Higher fat mass is associated with higher cystatin C after adjusting for measured GFR, probably from adipose tissue production and low-grade inflammation; the effect is modest (a few percent) but can nudge a borderline result across the 60 mL/min line.

  7. Smoking and inflammation

    Current smoking and raised inflammatory markers (CRP, IL-6) are each associated with cystatin C a few percent higher at the same measured GFR, which partly explains its strong link to cardiovascular events.

  8. Cancer and HIV

    Some solid tumors (melanoma, colorectal) and lymphomas, and untreated HIV infection, raise cystatin C independent of kidney function through increased cell turnover; it is one reason cystatin C is interpreted cautiously in oncology.

  9. Older age

    Cystatin C rises gradually after about 50, mostly reflecting the normal age-related fall in GFR of roughly 1 mL/min per year, but the equations adjust for age so that eGFRcys remains valid in the very old.

  10. Kidney transplant and drug effects

    Cystatin C is used to monitor transplant function; ciclosporin, tacrolimus and steroid regimens each shift it slightly, and a sudden rise can signal rejection before creatinine moves.

Symptoms that can go with it

  • None until kidney function is substantially reduced; a high cystatin C is usually found on routine testing
  • Fatigue, poor concentration and reduced appetite as waste products accumulate (eGFR usually under 30)
  • Swelling of the ankles, feet or around the eyes, and foamy urine if albumin is leaking
  • Needing to pass urine more often at night, or passing much less urine during acute kidney injury
  • Nausea, metallic taste, itching and muscle cramps in advanced disease
  • Breathlessness from fluid retention or anemia, and high blood pressure that is difficult to control
  • Symptoms of a non-kidney cause: weight loss and palpitations with hyperthyroidism, or a known high-dose steroid course

Low cystatin C

A cystatin C below the reference range, or at the low end of normal, is not a cause for concern in itself. It means the kidneys are filtering freely, and the eGFRcys will be reported as 90 or above (often capped at a value such as 'greater than 90' or 'greater than 120' because the equations are imprecise at high filtration). Young, healthy people and pregnant women, whose GFR rises by up to 50 percent, commonly read 0.5 to 0.7 mg/L.

The main non-kidney reason for a low value is an underactive thyroid, which slows cellular production of cystatin C by around 10 to 20 percent and can make the eGFRcys overestimate kidney function; once thyroid hormone is replaced the value rises to its true level. A low cystatin C in someone whose creatinine eGFR is reduced points toward a creatinine problem (high muscle mass, creatine supplements, a high meat intake, drugs that block creatinine secretion such as trimethoprim or cimetidine) rather than kidney disease, and the combined equation or a measured GFR is used to decide.

Common causes

  1. Normal or high kidney filtration

    The expected finding in healthy younger adults, in pregnancy (GFR rises by 40 to 50 percent) and in the early hyperfiltration phase of diabetes or obesity.

  2. Hypothyroidism

    Reduced thyroid hormone lowers cystatin C production and raises creatinine, so the two eGFRs diverge in opposite directions; both normalize with treatment.

  3. Low muscle mass with a reduced creatinine eGFR

    Cystatin C is not low in absolute terms here, but it reads normal when creatinine suggests disease, revealing that the creatinine result was misleading in a muscular person, someone taking creatine, or someone eating a lot of cooked meat.

  4. Assay and calibration differences

    Older, non-standardised assays read lower than current IFCC-calibrated methods; a result from a different lab may not be directly comparable.

  5. Very young children (after infancy)

    Between about 1 and 18 years cystatin C is slightly lower than adult values and pediatric ranges apply.

Symptoms that can go with it

  • None; a low cystatin C does not cause symptoms
  • If there are symptoms of hypothyroidism (tiredness, weight gain, cold intolerance, constipation), a low cystatin C may be masking mildly reduced kidney function and a TSH is worth checking

Read it alongside

  • Creatinine and creatinine-based eGFR — the two estimates are compared; agreement within 30 percent supports the result, disagreement points to a muscle-mass issue (creatinine) or a steroid, thyroid or inflammatory effect (cystatin C).
  • Combined creatinine-cystatin C eGFR (CKD-EPI 2021) — the most accurate estimate; used for staging and for dosing drugs with a narrow safety margin.
  • Urine albumin-to-creatinine ratio — albuminuria plus a reduced eGFR is the highest-risk combination; a normal UACR with eGFR 45 to 59 is where cystatin C decides whether CKD is present.
  • BUN and BUN-to-creatinine ratio — a high BUN with a normal cystatin C suggests dehydration, bleeding or high protein intake rather than kidney disease.
  • Potassium, bicarbonate and phosphorus — rise or fall as filtration declines and guide treatment once eGFR is under 45.
  • TSH — hyperthyroidism raises and hypothyroidism lowers cystatin C independent of the kidneys.
  • CRP — a high CRP with a modestly raised cystatin C suggests inflammation is contributing a few percent to the value.
  • Hemoglobin and PTH — anemia and secondary hyperparathyroidism develop as eGFR falls below about 45 and are monitored alongside.

What usually happens next

  1. A high cystatin C is first compared with the creatinine eGFR on the same sample; if the two agree and are under 60, the test is repeated after at least 3 months (sooner if the rise is new or symptoms suggest acute injury) to distinguish chronic kidney disease from a temporary fall.
  2. A urine albumin-to-creatinine ratio, urinalysis for blood and protein, blood pressure, glucose or A1C and often a kidney ultrasound follow, to find the cause and stage the disease (G and A categories).
  3. If the creatinine and cystatin C eGFRs differ by more than about 30 percent, expect questions about muscle mass, creatine or protein supplements, steroid use, thyroid symptoms and recent illness; a measured GFR (iohexol or iothalamate clearance) is sometimes arranged when the precise value matters, for example before chemotherapy or kidney donation.
  4. Medication doses are reviewed against the combined eGFR, particularly metformin, DOACs, gabapentin, antibiotics and chemotherapy, and NSAIDs are usually stopped.
  5. For confirmed chronic kidney disease, monitoring is every 3 to 12 months depending on stage, with nephrology referral for eGFR under 30, a fall of more than 25 percent in a year, or albuminuria above 300 mg/g.
  6. Questions to ask: which eGFR equation was used, do my creatinine and cystatin C results agree, what is my urine albumin ratio, and do any of my medicines need adjusting.

Diet, lifestyle and natural levers with evidence

What can move Cystatin C once the cause is known. Nothing here replaces finding the cause.

Blood pressure, salt and glucose control to slow kidney decline

Strong evidence

Nothing dietary or herbal lowers cystatin C directly; the number falls only if kidney filtration improves or a non-kidney cause is removed. What does change the trajectory is protecting the kidneys: keeping blood pressure under 130/80 mmHg, sodium under 2,300 mg a day and A1C around 7 percent slows eGFR decline by roughly 30 to 50 percent in trials of people with diabetic and hypertensive kidney disease, and ACE inhibitors, ARBs and SGLT2 inhibitors prescribed by your clinician reduce the risk of kidney failure by 20 to 40 percent on top of that.

Weight loss if overweight

Moderate evidence

Higher fat mass is associated with higher cystatin C at the same measured GFR, and weight loss lowers it: in studies of bariatric surgery, cystatin C fell by around 10 to 15 percent in the year after surgery alongside improvements in albuminuria and blood pressure, and modest diet-induced weight loss of 5 to 10 percent produces smaller but measurable reductions. Part of the change reflects less inflammation and part genuinely better kidney hemodynamics.

Stopping smoking

Moderate evidence

Current smokers have cystatin C values a few percent higher than non-smokers at the same measured GFR, and smoking roughly doubles the rate of progression of chronic kidney disease through vascular damage and higher blood pressure. Cohort studies show the excess risk of kidney function decline falls after quitting, and the cystatin C-based cardiovascular risk improves with it.

Checking medicines and thyroid function before interpreting the result

Moderate evidence

High-dose glucocorticoids raise cystatin C 10 to 30 percent and an overactive thyroid raises it 10 to 25 percent, while an underactive thyroid lowers it; treating the thyroid problem or finishing a steroid course returns the value to baseline. NSAIDs such as ibuprofen and naproxen reduce real filtration, especially in older adults and people on diuretics or ACE inhibitors, and stopping them can raise the eGFR by several mL/min within weeks. Creatine supplements and large meat meals affect creatinine but not cystatin C, which is one reason the two are compared.

Do not stop prescribed steroids or thyroid medication because of a cystatin C result; ask your clinician how the result should be read in light of them.

When to see a clinician promptly

  • A cystatin C that has risen sharply over days, or an eGFRcys under 30 on a new test, especially with reduced urine output, vomiting, confusion or breathlessness: possible acute kidney injury, which needs same-day assessment.
  • A high cystatin C with swelling of the legs or face, foamy urine, or blood in the urine: possible glomerular disease or nephrotic syndrome.
  • An eGFR under 60 on two tests at least 3 months apart that has not yet been staged with a urine albumin-to-creatinine ratio and blood pressure review.
  • A fall in eGFR of more than 25 percent within a year, or an eGFR under 30, which are the usual thresholds for nephrology referral.
  • A reduced eGFR in anyone taking metformin, a DOAC, lithium, NSAIDs or chemotherapy, so doses can be reviewed.
  • Chest pain, severe breathlessness, muscle weakness or an irregular heartbeat in someone with known kidney disease: possible high potassium or fluid overload, which are emergencies.

Frequently asked questions

What is a normal cystatin C level?

About 0.6 to 1.0 mg/L in adults on most current assays, with laboratory ranges running from roughly 0.5 to 1.2 mg/L depending on the method and the age group it was set on. Values creep up slightly with age. The more useful number on the report is the eGFR calculated from it: 90 or above is normal, 60 to 89 mildly reduced, and under 60 for 3 months or more is chronic kidney disease. Newborns normally have much higher values, up to about 2.5 mg/L, which fall during the first year.

What does a high cystatin C mean?

Most often that the kidneys are filtering less than normal: a value of 1.2 to 1.5 mg/L roughly corresponds to an eGFR of 45 to 60, 2 mg/L to about 30 and 3 mg/L to under 20. The same report will show the eGFRcys. Less commonly, cystatin C is high with normal kidneys because of high-dose corticosteroids, an overactive thyroid, obesity, smoking, inflammation or cancer. Your clinician will compare it with your creatinine eGFR, check your urine for albumin and repeat it after 3 months to decide whether it is chronic kidney disease.

Cystatin C vs creatinine: which is more accurate?

Cystatin C is less biased by muscle mass, diet and sex, so it is more accurate in people who are very muscular, frail, elderly, malnourished, amputees, or eating very high- or low-meat diets, and it detects early kidney decline and predicts cardiovascular events better. Creatinine is cheaper, more widely available and less affected by steroids, thyroid disease and inflammation. The combined creatinine-cystatin C equation (CKD-EPI 2021) is more accurate than either alone, which is why guidelines recommend measuring both when the creatinine-based eGFR is 45 to 59 with no albuminuria or when an accurate value matters.

Why is my cystatin C high but my creatinine normal?

The commonest reason is low muscle mass: in older, slim or frail people and in those with muscle-wasting conditions, creatinine production is low, so a 'normal' creatinine hides a reduced GFR that cystatin C reveals. Studies suggest up to a third of older adults with a normal creatinine have an eGFRcys under 60. The other possibilities are non-kidney causes of a high cystatin C, such as high-dose steroids, an overactive thyroid, obesity, smoking or inflammation. The combined equation or a measured GFR resolves the discrepancy.

Why is my creatinine high but my cystatin C normal?

This usually means the creatinine is misleading rather than the kidneys being damaged: high muscle mass, creatine supplements, a large cooked-meat meal before the test, or drugs that block creatinine secretion into the urine (trimethoprim, cimetidine, some HIV drugs and newer antibiotics) all raise creatinine without changing filtration. An underactive thyroid can produce the same pattern by lowering cystatin C and raising creatinine. In these cases the cystatin C or combined eGFR is the better guide.

Can cystatin C be lowered?

Only by improving kidney filtration or removing a non-kidney cause. Treating dehydration, stopping NSAIDs, finishing a steroid course or controlling an overactive thyroid can each bring it down within days to weeks. For chronic kidney disease the aim is to slow the rise: blood pressure control, ACE inhibitors or ARBs, SGLT2 inhibitors, glucose control, salt reduction, weight loss and not smoking all slow eGFR decline. No supplement or herbal product has been shown to lower cystatin C or improve measured GFR.

Does cystatin C predict heart disease?

Yes, more strongly than creatinine. In the Cardiovascular Health Study of adults aged 65 and over, each step up in cystatin C was linked to a graded rise in death, heart attack, stroke and heart failure, with the top fifth (above 1.29 mg/L) having roughly twice the risk of the bottom fifth, even among people whose creatinine was normal. The association partly reflects true kidney impairment and partly the links between cystatin C, inflammation and vascular damage. It is not yet used routinely as a cardiac risk score, but a high-normal value is a reason to attend to blood pressure, cholesterol and smoking.

Do I need to fast for a cystatin C test, and when is it ordered?

No fasting is needed and the time of day does not matter, though a large meat meal shortly before will affect the creatinine drawn with it. It is ordered to confirm chronic kidney disease when the creatinine eGFR is 45 to 59 with normal urine albumin, in people with unusual muscle mass (bodybuilders, amputees, frail older adults, people with cirrhosis or neuromuscular disease), before dosing drugs that are cleared by the kidney, to assess potential kidney donors, and increasingly as part of a standard kidney panel in older adults.

References

  1. Cystatin C test. MedlinePlus, US National Library of Medicine (2023)View source
  2. Cystatin C. National Kidney Foundation (2023)View source
  3. Inker LA, Eneanya ND, Coresh J, et al.. New creatinine- and cystatin C-based equations to estimate GFR without race. New England Journal of Medicine (2021)
  4. Inker LA, Schmid CH, Tighiouart H, et al.. Estimating glomerular filtration rate from serum creatinine and cystatin C. New England Journal of Medicine (2012)
  5. Shlipak MG, Matsushita K, Ärnlöv J, et al.. Cystatin C versus creatinine in determining risk based on kidney function. New England Journal of Medicine (2013)
  6. Shlipak MG, Sarnak MJ, Katz R, et al.. Cystatin C and the risk of death and cardiovascular events among elderly persons. New England Journal of Medicine (2005)
  7. Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney International (2024)
  8. Delgado C, Baweja M, Crews DC, et al.. A unifying approach for GFR estimation: recommendations of the NKF-ASN Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Disease. American Journal of Kidney Diseases (2021)
  9. Stevens LA, Schmid CH, Greene T, et al.. Factors other than glomerular filtration rate affect serum cystatin C levels. Kidney International (2009)
  10. Knight EL, Verhave JC, Spiegelman D, et al.. Factors influencing serum cystatin C levels other than renal function and the impact on renal function measurement. Kidney International (2004)
  11. Evaluation of the renal patient. Merck Manual Professional Version (2024)

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This page is educational and is not medical advice or a diagnosis. Lab results have to be interpreted together with your history, symptoms and other results by a clinician who knows you. Do not start or stop a supplement to change a lab value before the cause is known.