Glomerular filtration rate
The body keeps the kidneys active 24 hours a day to remove excess fluid, drugs, salt, and metabolic waste. Blood flows through the kidneys 300 times a day. A disease of the kidneys often progresses slowly. The symptoms are not initially noticed, or they can be vague. When the kidneys stop working, humans cannot survive without dialysis.
The state of the kidneys can be assessed by measuring the filtration rate of the glomeruli (Pt-GFRe). The GFRe value is calculated from the creatinine value (fS-Krea), which provides a more detailed account of kidney function.
Creatinine (Krea) originates in the creatine and phosphocreatine in the muscles. The amount of muscle mass therefore has an impact on the blood creatinine level. Creatinine is removed from the body by being filtrated in the glomeruli of the kidneys.
When should GFRe be measured?
The Pt-GFRe test is used when wanting to investigate kidney function.
Because the symptoms of kidney diseases can be very slight or vague, they can be difficult to identify. Here are a few symptoms in connection with which the Pt-GFRe level should be measured:
- Decreased urination
- Swelling on the face and limbs
- Shortness of breath
- Loss of appetite, nausea, vomiting
- High blood pressure
- Shivering and fatigue
What does the GFRe test measure?
GFRe measures kidney function. GFR measures the filtration rate of the glomeruli in the kidneys. The result is obtained by calculating it using a formula. The formula depends on age, sex, and level of blood creatine.
How to interpret the GFRe test result?
The test is based on the body’s creatinine concentration (S-Krea). Age and sex are taken into consideration in interpreting it. The test can only be used in adults, meaning those aged over 18. The result is reported normalised per average adult body area of 1.73 m2.
Normally, the result is:
- 18–39 years: over 89 ml/min/1.73 m2
- 40–49 years: over 83 ml/min/1.73 m2
- 50–59 years: over 77 ml/min/1.73 m2
- 60–69 years: over 69 ml/min/1.73 m2
- ≥70 years: over 59 ml/min/1.73 m2
Classification of kidney failure (unit ml/min/1.73m2):
- over 90: normal kidney function
- 60–89: mild kidney failure (not significant if the patient has no other symptoms of kidney disease)
- 45–59: mild or moderate kidney failure
- 30–44: moderate or severe kidney failure
- 15–29: severe kidney failure
- below 15: end-stage kidney failure, dialysis patients
Please contact your physician or other healthcare professional if you suspect an illness or need help interpreting the results.
What can cause elevated levels in the GFRe?
When kidney function is normal, the GFRe level exceeds the reference value. The GFR level increases by 10–30% during pregnancy.
What can cause decreased levels in the GFRe?
A decreased Pt-GFRe blood level can indicate impaired filtration in the kidneys, meaning kidney failure. Kidney failure can be caused by diseases of the veins in the kidneys, chronic high blood pressure, certain medicinal agents, and repeated kidney infections.
A meat meal eaten right before sampling can affect the test result. If creatinine is elevated and/or Pt-GFRe is low, this can be caused by medication, physical activity, or loss of fluid caused by an intestinal disease.
Weakening kidney function is indicated by a decreasing Pt-GFRe result.
The most typical additional GFRe tests:
- Cystatin C reveals kidney failure (1887 S-KystC)
SYNLAB test list:
Terveyskirjasto health library: Glomerulusten suodatusnopeus (GFR) arvioituna CKD-EPI-kaavalla (Pt-GFReEPI) https://www.terveyskirjasto.fi/terveyskirjasto/tk.koti?p_artikkeli=snk02001
Fresenius Medical Care: Munuaissairaus https://www.freseniusmedicalcare.fi/fi/potilaat-ja-perheet/munuaissairaus/
Reunapaikka: Munuaisten toiminta, Nina Eriksson
Fasting is not required
This examination does not require fasting