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Doctor's Assessment Included

Every result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.

Kidney

Fasting Glucose: What Does Your Blood Sugar Say?

Fasting glucose measures the sugar in your blood after not eating for at least 8 hours. This test provides insight into how your body processes blood sugar. An abnormal fasting glucose value may indicate changes in your sugar metabolism. As you age, the way your body processes sugar may change. Monitoring your fasting glucose value can therefore be useful. The information on this page is intended as general information and is not a substitute for professional medical advice. Always discuss your results with a doctor.

Reference Ranges

Male
ml/min
Low > 90 Normal
Female
ml/min
Low > 90 Normal

Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.

What It Measures

eGFR is not a direct measurement but a calculation. Based on your creatinine, age, and sex, it estimates how many millilitres of blood your kidneys filter per minute. The CKD-EPI formula is the current standard in the Netherlands.

Chronic kidney disease staging based on eGFR is: > 90 ml/min is normal (stage 1), 60–89 is mildly reduced (stage 2), 45–59 is mildly to moderately reduced (stage 3a), 30–44 is moderately to severely reduced (stage 3b), 15–29 is severely reduced (stage 4), and < 15 ml/min is kidney failure (stage 5).

An eGFR between 60 and 90 without other signs of kidney damage (protein in urine, abnormal urine sediment) is often physiological in the elderly and does not necessarily indicate disease.

Why It Matters

Chronic kidney damage is largely irreversible, but progression can be slowed or stopped if detected early. eGFR is the cornerstone of that early detection. Diabetes and high blood pressure together account for more than 60% of all cases of chronic kidney damage — periodic eGFR monitoring in these patient groups is therefore essential.

At an eGFR below 60 ml/min, medication adjustments are often needed because many drugs are excreted by the kidneys. The dosage of contrast agents for CT scans must also be adjusted.

When to Test

eGFR is automatically calculated when creatinine is measured. It is useful with risk factors for kidney damage: diabetes, high blood pressure, family history of kidney problems, long-term NSAID use, and for everyone over 50 as part of a preventive check. Fasting is not required.

Symptoms

Low Levels

A decreased eGFR (below 60 ml/min) usually causes no symptoms in early stages. Only at an eGFR below 30 ml/min do symptoms occur such as fatigue, decreased appetite, nausea, itching, swollen ankles, and changes in urine output. At an eGFR below 15 ml/min (kidney failure), dialysis or transplantation is necessary.

High Levels

A high eGFR (above 90 ml/min) is normal and causes no symptoms. Values above 120 ml/min can occur with hyperfiltration, sometimes seen in type 1 diabetes or during pregnancy. This is a phase that can precede kidney damage.

Recommendations

Male

If Low

Low eGFR indicates reduced kidney function. Consult a nephrologist for evaluation and management.

If High

Normal to high eGFR indicates healthy kidney function. Maintain kidney-healthy habits.

Female

If Low

Low eGFR indicates reduced kidney function. Consult a nephrologist for evaluation and management.

If High

Normal to high eGFR indicates healthy kidney function. Maintain kidney-healthy habits.

Lifestyle Tips

Keep your blood pressure below 130/80 mmHg and blood sugar well regulated if you have diabetes — these are the two most effective measures to slow kidney function loss. Limit NSAID use, drink enough water, and avoid extremely high protein intake with already reduced kidney function. Stopping smoking also protects kidney function.

Frequently Asked Questions

What is a normal eGFR value?
An eGFR above 90 ml/min is normal. Between 60 and 89, it may be mildly reduced but is often physiological in the elderly. Below 60 ml/min indicates clinically relevant kidney function reduction.
What does eGFR according to CKD-EPI mean?
CKD-EPI is the formula used to calculate eGFR based on your creatinine, age, and sex. It is more accurate than the older MDRD formula, especially at normal or mildly reduced kidney function.
Can eGFR be temporarily decreased?
Yes, dehydration, intense exercise, a heavy protein-rich meal, or fever can temporarily raise creatinine and thus lower eGFR. With a borderline value, it is wise to repeat the test after a few weeks.
What is the difference between eGFR and creatinine?
Creatinine is the raw blood value. eGFR is a calculation that corrects creatinine for your age, sex, and ethnicity, providing a more accurate estimate of your actual kidney function.
How can I protect my kidney function?
Keep blood pressure and blood sugar under control, limit NSAID use, drink enough water, do not smoke, and avoid extremely high protein intake. Have your eGFR checked periodically if you have risk factors.
Do I need to fast before an eGFR test?
No, fasting is not required. However, avoid intense strength training and a very protein-rich meal just before the blood draw.