GFR Black Blood Test Results Explained


Glomerular Filtration Rate [GFR] is a blood test that is used to detect early kidney damage. It may also be used to monitor the status of the kidneys. It is typically performed by ordering a creatinine blood test and the calculating the estimated GFR rate from those results. It can be ordered independently or as part of a basic metabolic or comprehensive metabolic panel. It may also be ordered along with a blood urea nitrogen test.

People with hypertension, diabetes, and other chronic conditions that may lead to future kidney damage often have this test regularly ordered. The National Kidney Foundation recommends that this calculation occur every time a creatinine blood test is ordered.

When To Ask About the GFR Black Blood Test

Any time an individual is experiencing the signs and symptoms of kidney disease is a good time to discuss having the GFR black blood test ordered. A common sign of kidney malfunction is swelling or puffiness that happens around the eyes, the face, the ankles, or the abdomen. This swelling will not improve over time.

Urine that is foamy is also a symptom of kidney trouble and may or may not have extra protein in it. The urine may also have blood in it or look like coffee or chocolate milk. There may also be decreased urination, problems with urinating, back below the ribs in the mid-back, and high blood pressure.

Advanced symptoms which develop as kidney disease worsens includes ongoing fatigue, itchiness, a loss of appetite, darkened skin, muscle cramps, and changes to urination habits.

What Do My Test Results Mean?

The GFR black blood test is used to detect kidney disease in its early stages. It is more reliable than just the estimated rates that happen from the creatinine blood test alone. Test results are interpreted with a person’s medical history and the number that they are given from their results based on a generalized chart.

Here are the numbers and what the findings typically represent.

A GFR that is 90+. This indicates minimal kidney damage at most because GFR levels are normal. Protein or albumin in the urine may be high and casts might be seen in the urine.
A GFR that is 60-89. This test result indicates a mild decrease in GFR and that mild to moderate kidney damage may have occurred.
A GFR that is 30-59. This is an indication that there is at least moderate damage to the kidneys.
AGFR that is 15-29. This indicate a severe decrease in GFR and critical damage to the kidneys. Complete failure may occur in the near future.
A GFR that is below 15. This indicates organ failure.

Each bullet point is also assigned a kidney damage stage from 1-5, with a GFR that is 90+ being damage stage #1. It is used instead of the creatinine blood test because people with different levels of muscle mass produce different levels of creatinine, so the estimated results may not be as accurate as they need to be. This is especially true for people who are obese, malnourished, are vegetarians, or take dietary supplements which include creatinine.

Treatment plans to address the kidney disease are then created based on the GFR black blood test results explained here and the medical history of the patient.

Here’s What You Need to Know

The calculation of the GFR is intended to be used as a measurement only when kidney functions and creatinine levels are considered stable. If there are rapid changes to kidney function, then the filtration rates can be difficult to detect and/or estimate. This is especially true for individuals who are suffering from acute kidney failure.

Certain drugs are also known to increase creatinine levels. Medical providers will want to know if a patient has been taken cisplatin, cefoxitin, or gentamicin in particular.

Any health condition which reduces the amount of blood that flows to the kidneys will also affect the blood test results. This is why a diagnosis must include current and previous health issues that have been addressed at the individual level. GFR estimates from creatinine levels are also considered invalid for anyone over the age of 75.

The GFR black blood test results explained here are designed to help provide awareness to a potentially critical health issue. This guide is not intended to substitute as a diagnosis. Only a medical provider can determine if a patient has kidney disease and how much damage may have occurred. If you are experiencing the symptoms listed here, consult with your doctor right away about how to address the health issues that are present.