A decrease or decline in the GFR implies progression of underlying kidney disease or the occurrence of a superimposed insult to the kidneys. This is most commonly due to problems such as dehydration and volume loss.
Hydration affects GFR and natriuresis under fasting conditions and after a meat meal.
Classically dehydration results in a 'pre-renal state' associated with intrarenal vasoconstriction but with relative maintenance of glomerular filtration rate (GFR).
Some studies have shown that frequent dehydration, even if it's mild, may lead to permanent kidney damage. Dehydration can cause a build-up of wastes and acids in the body, and it can clog the kidneys with muscle proteins (myoglobin). All these things can hurt the kidneys.
As chronic kidney disease progresses, your GFR number decreases. * Your GFR number tells your doctor how much kidney function you have. As chronic kidney disease progresses, your GFR number decreases.
GFR generally declines at a rate of 1 mL/min/year.
The estimated glomerular filtration rate (eGFR) is variable and it relies on a blood test, which may have day to day variations and it is an "estimation". Hence, the more times you do the test, the more accurate will be the estimate.
How do I get ready for the test? Healthcare providers may tell you not to eat or drink anything, except water, after midnight. You may also be asked not to eat any cooked meat the night before the test. It can increase the level of creatinine in your blood and affect your GFR results.
Dehydration generally causes BUN levels to rise more than creatinine levels. This causes a high BUN-to-creatinine ratio. Kidney disease or blocked urine flow from your kidney causes both BUN and creatinine levels to rise.
Water helps the kidneys remove wastes from your blood in the form of urine. Water also helps keep your blood vessels open so that blood can travel freely to your kidneys, and deliver essential nutrients to them. But if you become dehydrated, then it is more difficult for this delivery system to work.
Dehydration does cause the serum creatinine to rise and the estimated glomerular filtration rate (eGFR) will, accordingly, fall. The degree of change is generally proportional to the degree of dehydration.
Whilst all fluid counts towards your fluid intake, water is one of the healthiest choices when it comes to maintaining kidney health. Sip water little and often. Women should aim to drink eight 200ml glasses of fluid a day. Men should aim to drink ten 200ml glasses of fluid a day.
eGFR values derived from serum creatinine are frequently inaccurate when compared against GFR reference methods. The cause of this inaccuracy is likely related to non-functional factors, including unmeasured muscle mass and tubular secretion of creatinine.
In this population-based study, we examined factors associated with glomerular filtration rates (GFR) in both genders. The findings of our study showed that obesity, diabetes, blood urea nitrogen, atherogenic factor, hypertension, meat consumption, and smoking were associated with lower GFR.
Avoid processed foods and choose fresh fruits and vegetables instead. Follow a low-salt diet. Salt should be limited especially if you have high blood pressure, protein in your urine, or swelling, or difficulty breathing. Eating less than 2000 mg a day of sodium is recommended.
When you have not drank enough fluids your kidneys try to save as much water as they can and cause your urine to be darker in colour (more concentrated). Dark yellow urine is a sign that you are dehydrated and that you must drink more fluids to prevent dehydration.
Other conditions, such as heart failure and dehydration, can also cause low clearance levels. Low BUN-to-creatinine ratios may be linked with a diet low in protein, a severe muscle injury called rhabdomyolysis, pregnancy, cirrhosis, or syndrome of inappropriate antidiuretic hormone secretion (SIADH).
Before the test
For many renal panel tests, you will need to fast for 8 to 12 hours before your blood draw. During this time, you can only drink water. You cannot eat any food or drink other beverages.
In normal individuals, glomerular filtration rate (GFR) measured by inulin and creatinine clearance reaches a maximum during the day, peaking around 2–3 p.m., and a minimum in the middle of the night [11–13].
No preparation is needed and you can have this blood test at any time of the day. The urine albumin or protein creatinine ratio test is best done in the early morning if possible.
The average drop in the estimated glomerular filtration rate (eGFR) is about 1 cc per minute per 1.73 meters squared per year just on the basis of natural aging. Patients with some forms of kidney disease such as diabetes and glomerulonephritis can drop by 5 to 10 per year.
Of those who fasted, 11.1% had a drop in Glomerular Filtration Rate (eGFR) of 20% or more. Those who did not fast (16.7%) presented a similar drop.
Kidney Disease: Improving Global Outcomes (KDIGO) guidelines define rapid progression as rate of eGFR declines > 5 mL/min per 1.73m2 per year [1, 2].