Blood tests for kidney health

For people with chronic kidney disease (CKD) and people at higher risk of it, such as those with diabetes, high blood pressure, heart disease or a family history of kidney failure.

10 tests explainedAI-verified against cited sources. Awaiting expert reviewLast reviewed 2026-10-19

Early kidney disease usually causes no symptoms, so blood and urine tests are how it is found and followed. Guidelines pair two numbers: eGFR, an estimate of how well the kidneys filter, and uACR, a urine test for the protein albumin. As kidney function changes, clinicians also watch potassium, bicarbonate, hemoglobin and the minerals that keep bones healthy. Trends over several tests tell more than any single result.

The tests that matter most

Most important first. Each one links to its full page, where the note for this group sits near the top.

eGFR (Creatinine-based)
eGFR is the main number for how well the kidneys filter. KDIGO 2024 suggests checking it together with a urine albumin test in people at risk, and at least once a year in people with CKD. NIDDK advises a yearly check for people with diabetes.
Sources: KDIGO (2024) and NIDDK (2016)
Usual adult range
60 and above mL/min/1.73 m²
Urine Albumin/Creatinine Ratio (uACR)
Kidney damage can show up in eGFR, in urine albumin, or in both, which is why guidelines check uACR alongside eGFR. Because results vary from day to day, a high uACR is usually confirmed on repeat samples before it counts.
Sources: KDIGO (2024) and American Diabetes Association (2025)
Usual adult range
0–30 mg/g
Creatinine
eGFR is worked out from creatinine, so anything that moves creatinine moves eGFR. KDIGO 2024 lists high muscle mass, high-protein diets, creatine supplements and a recent cooked meat or fish meal among the things that change creatinine without any change in the kidneys.
Source: KDIGO (2024)
Men, 15+
0.74–1.35 mg/dL
Women, 16+
0.59–1.04 mg/dL
Cystatin C
Creatinine is tied to muscle mass, while cystatin C is swayed by other things, such as steroid medicines and thyroid problems. KDIGO 2024 recommends adding it when a creatinine-based eGFR may be off and the number will guide a decision, such as confirming or staging CKD or choosing a medicine dose. The estimate then combines creatinine and cystatin C.
Source: KDIGO (2024)
18–49
0.63–1.03 mg/L
50+
0.67–1.21 mg/L
Potassium
High potassium is uncommon when eGFR is above 60 and becomes more common as kidney function falls, though it is not inevitable. Some common blood pressure and kidney medicines can raise it too. KDIGO 2024 lists potassium among the CKD lab changes to follow.
Source: KDIGO (2024)
Usual adult range
3.5–5.2 mmol/L
Bicarbonate (Total CO2)
As kidney function falls, the kidneys make less bicarbonate, and the blood can slowly become more acidic. KDIGO 2024 notes that bicarbonate (often printed as CO2) starts to fall once eGFR drops below 60, and it is one of the CKD lab changes clinicians watch and may treat.
Source: KDIGO (2024)
Usual adult range
20–29 mmol/L
Hemoglobin
Anemia becomes more common as kidney function falls. KDIGO 2024 notes that average hemoglobin is lower in people with an eGFR below 60 and keeps falling as eGFR drops, so clinicians often check hemoglobin in people with CKD.
Source: KDIGO (2024)
Men, 16+
13–17.7 g/dL
Women, 16+
11.1–15.9 g/dL
Phosphorus (Phosphate)
Changes in phosphorus, calcium and PTH start early in CKD and grow as eGFR falls, a pattern called CKD-mineral and bone disorder. Phosphorus is read together with calcium and PTH rather than alone.
Source: KDIGO (2024)
Usual adult range
2.5–4.5 mg/dL
Calcium, Total
Calcium is one of the lab values KDIGO 2024 groups under CKD-mineral and bone disorder, along with phosphorus, PTH and vitamin D. These shifts begin early in CKD, so calcium is followed over time with phosphorus and PTH.
Source: KDIGO (2024)
18–59
8.7–10.2 mg/dL
Men, 60+
8.6–10.2 mg/dL
Parathyroid Hormone (PTH), Intact
PTH (parathyroid hormone) keeps blood calcium steady. KDIGO 2024 notes that PTH, calcium and phosphorus start to change early in CKD and change more as eGFR falls, so PTH is read together with the other two.
Source: KDIGO (2024)
Usual adult range
18–59 pg/mL

Ranges shown are the usual adult ranges labs print. The range on your own report is the one your result is judged against.

Getting results you can compare

For uACR, KDIGO prefers a first-morning urine sample. Exercise in the past 24 hours, an infection or fever, a period and very high blood sugar can all raise uACR without any kidney damage.
Sources: KDIGO (2024) and American Diabetes Association (2025)
A cooked meat or fish meal can raise creatinine, with the biggest effect 2 to 4 hours later, and so lower eGFR. KDIGO notes that waiting at least 12 hours after meat or fish best avoids this, while admitting it can be hard to arrange.
Source: KDIGO (2024)
Potassium results vary with the time of day, the season, whether the lab used serum or plasma, and some medicines, so compare results drawn in similar conditions.
Source: KDIGO (2024)
CKD means changes that last at least 3 months, so guidelines repeat an unexpected low eGFR or high uACR to confirm it before calling it CKD.
Sources: KDIGO (2024) and NIDDK (2016)

Good to know

eGFR moves around from test to test. For people with CKD, KDIGO 2024 says a change of more than 20% on the next test is bigger than the usual variation and worth a closer look. For uACR, a doubling is the change worth a closer look.
Source: KDIGO (2024)
A creatinine-based eGFR can be off when creatinine is made at an unusual rate, for example in bodybuilders, after an amputation or spinal cord injury, and with vegetarian, keto or high-protein diets or creatine supplements. That is when KDIGO suggests cystatin C.
Source: KDIGO (2024)

Questions you could ask

What are my eGFR and uACR, and which CKD stage do they put me in?
How often should we recheck my kidney tests?
Would a cystatin C test give a more accurate eGFR for me?
Could any of my medicines be affecting my potassium or creatinine?
Which other results, such as hemoglobin or phosphorus, are worth watching for me?

Sources

KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease, KDIGO (2024)
Chronic Kidney Disease Tests & Diagnosis, NIDDK (2016)
11. Chronic Kidney Disease and Risk Management: Standards of Care in Diabetes 2025, American Diabetes Association (2025)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-19. How we build and check these pages.

Educational information, not medical advice. Blood Test Tracker doesn’t diagnose or treat, and it doesn’t replace your clinician. Talk with your clinician before changing medications, supplements or care.