Many patients encounter kidney disease as a result of a high creatinine value in a blood test they have done by chance, and they get demoralized. High creatinine is a common problem (in our country, one out of 6-7 adults has kidney problems and about one out of 20 adults has high creatinine) and most of the patients are not even aware of it. Therefore, you may even be glad to realize it because now you can protect your kidneys by paying more attention to them. On this page, you will find the most frequently asked questions by patients and their relatives about creatinine.
What is creatinine?
Creatinine is an easy-to-measure substance that is formed in muscle cells, excreted from the body through the kidney, and shows whether the kidney is doing its job well.
What is urea?
Many biochemical events happen in our body for life. For example, proteins participate in many events and are eventually broken down. The broken down proteins become urea and are excreted from the body.
Why are urea and creatinine elevated in kidney failure?
Urea and creatinine are excreted by the kidneys. In renal failure, urea and creatinine begin to accumulate because the filtering function of the kidney is reduced. By measuring urea or creatinine in the blood, it is determined whether there is kidney failure and the degree of kidney failure, if any.
Are elevated blood urea and creatinine all due to kidney failure?
Especially in mild elevations, it may increase for other reasons (for example, problems with protein or muscles), but these reasons will not be mentioned here. Only a kidney disease (nephrology) specialist can tell you whether the high urea and creatinine level is due to a kidney or non-renal cause.
What kind of problem can be in the muscles?
Since muscle mass has increased in people who do heavy sports, creatinine may increase in the blood. On the other hand, people with very reduced muscle mass may have kidney disease even though their blood creatinine is within normal limits.
Urea or important creatinine?
Both are important. It has become a habit to understand more urea when kidney failure is mentioned. In ancient times, urea was checked because it is easier to look at the level of urea in the blood than the level of creatinine. It has become much easier to look at creatinine with automatic machines. Urea is affected by many non-renal factors compared to creatinine, so it is less sensitive, prone to misconceptions, that is, the kidney is more likely to be normal even though urea is high. In other words, creatinine is more important for kidney failure, but although creatinine is high, the kidney can also be normal.
Are both kidneys sick?
If the cause of high creatinine is kidney disease, both kidneys must be sick. People who have donated one kidney to their relatives have only one kidney and creatinine does not rise as long as this kidney is healthy.
Does creatinine decrease with drinking water?
It may decrease slightly, but if there is permanent kidney damage, it will not return to normal. The important thing is not that creatinine falls, but that it does not rise or rises slowly.
Will creatinine decrease if I don’t eat meat?
It may fall, but this is mostly due to weakening of the muscles due to malnutrition, not better functioning of the kidneys. If the muscles are weak, creatinine production may decrease, so creatinine in the blood may decrease. Moreover, since proteins such as meat are eaten less, giving weight to vegetables and fruits can also cause a potassium problem. The best thing to do is to listen to the doctor.
How can I prevent creatinine from rising?
In general, it is necessary to prevent unnecessary drug use, to use drugs consciously if necessary, to take adequate fluids, to control blood pressure effectively (even if there is no complaint) and to follow up with a nephrologist. ‘How can I get rid of being a dialysis patient?’ This section may be useful to you.
Why is blood pressure monitoring important?
High blood pressure causes rapid progression of kidney failure and increased creatinine value. I recommend you my book named ‘I’m so glad my blood pressure is out’ (Doğan Kitap, 2016).
Can elevated creatinine be a symptom of another kidney disease?
Yes. Throughout my medical life, I diagnosed many different diseases in my patients because of the high creatinine value. In some blood diseases and hormonal disorders, the first finding may be creatinine elevation, so the initial evaluation is very important.
I have no complaints about my kidneys, my doctor said that my kidney is sick, is such a thing possible? How is early kidney failure diagnosed?
In the early period of kidney failure, the patient may have no signs or symptoms. During this period, kidney disease can only be detected by measuring urea or creatinine in the blood. This is why it is called ‘kidney disease is insidious’. The rise of urea and creatinine is not felt. Slight elevations may be ignored or neglected by both the patient and the physician.
What are the normal levels of urea and creatinine in the blood?
Normal values are 20-50 mg/dl for urea and 0.8-1.2 mg/dl for creatinine. These values may vary slightly according to laboratories.
I’ve heard of BUN, what is it?
Although its normal values are different, practically urea is 2 times the BUN. It has become a habit to speak of urea. Some laboratories report it as urea and some as BUN. BUN is the abbreviation for blood urea nitrogen.
What is the normal BUN value?
10-20 mg/dl.
Is there a relationship between elevated urea, BUN or creatinine levels and the degree of renal failure?
Yes. To understand the degree of kidney failure, the filtering function of the kidney is measured using formulas based on the blood creatinine level. The medical term used to describe the filtering function of the kidney is creatinine clearance. The unit used in practice is ml/minute.
Why is creatinine clearance important?
Blood creatinine level reflects the degree of renal impairment better than urea or BUN. Since factors such as age, gender, race and muscle mass affect the blood creatinine level, the concept of creatinine clearance has been developed in order to reduce the effect of these factors.
Renal failure/disease is staged according to creatinine clearance and treatment plan is made accordingly.
How can I find out my creatinine clearance?
To calculate creatinine clearance, the ideal is to collect urine for 1 day (24 hours) and make the necessary measurements, but since this is not practical, some formulas and tables have been developed. Today, while many hospitals report blood creatinine level, they also report creatinine clearance (GFR, GFD, eGFD, eGFD) with a small warning below.
How accurate is the value found with these formulas?
There are small differences between the values found by these formulas and the actual values, but this difference is of little importance in nephrology practice. These formulas cannot be used in transient renal failure where the filtering function of the kidney changes rapidly.
Is it necessary to collect urine for 24 hours?
It used to be very common in the past, but thanks to these formulas, most patients no longer need to collect urine for 24 hours. In those who do heavy sports, it can be understood by collecting urine for 24 hours that the high creatinine is the result of kidney disease or an increase in muscle mass.
There is no information such as creatinine clearance, GFR, GFD, eGFD, eGFD in my analysis paper, how can I find out?
Patients can approximately calculate their own creatinine clearance by means of the following 2 tables prepared according to the MDRD formula.
Table for male patients
| Creatinine level | ||||||||
| Age | 1 | 1.5 | 2 | 2.5 | 3 | 4 | 6 | 8 |
| 20 | 101 | 63 | 46 | 35 | 28 | 20 | 13 | 9 |
| 25 | 97 | 61 | 43 | 34 | 27 | 20 | 12 | 9 |
| 30 | 93 | 58 | 42 | 32 | 26 | 19 | 12 | 8 |
| 35 | 90 | 57 | 41 | 31 | 25 | 18 | 11 | 8 |
| 40 | 88 | 55 | 40 | 31 | 25 | 18 | 11 | 8 |
| 50 | 84 | 53 | 38 | 29 | 24 | 17 | 11 | 8 |
| 60 | 81 | 51 | 36 | 28 | 23 | 16 | 10 | 7 |
| 70 | 79 | 49 | 35 | 27 | 22 ( | 16 | 10 | 7 |
| 80 | 76 | 48 | 34 | 27 | 22 | 15 | 10 | 7 |
Example: In a 20-year-old male patient with a creatinine level of 1 mg/dl, the creatinine clearance was 101 ml/min.
Table for female patients
| Creatinine level | ||||||||
| Age | 1 | 1.5 | 2 | 2.5 | 3 | 4 | 6 | 8 |
| 20 | 75 | 47 | 34 | 26 | 21 | 15 | 10 | 7 |
| 25 | 72 | 45 | 32 | 25 | 20 | 14 | 9 | 7 |
| 30 | 69 | 43 | 31 | 24 | 19 | 14 | 9 | 6 | 35 | 67 | 42 | 30 | 23 | 19 | 14 | 8 | 6 |
| 40 | 65 | 41 | 29 | 23 | 18 | 13 | 8 | 6 |
| 50 | 62 | 39 | 28 | 22 | 18 | 13 | 8 | 6 |
| 60 | 60 | 38 | 27 | 21 | 17 | 12 | 8 | 5 |
| 70 | 58 | 36 | 26 | 20 | 16 | 12 | 7 | 5 |
| 80 | 57 | 36 | 25 | 20 | 16 | 11 | 7 | 5 |
Ms. Ayşe is 40 years old. It weighs 72 kg. Blood creatinine level is 2.5 mg/dl. What is the creatinine clearance?
23 ml/min according to the table.
Is there a way for me to learn other than these tables?
You can also learn with some web pages or mobile phone applications.
What is the use of calculating and learning the creatinine clearance?
In a patient with renal failure, creatinine clearance is based on when planning treatment. In 2002, the National Kidney Foundation in the United States classified permanent kidney diseases based on creatinine clearance and prepared a treatment plan for patients. Here, this staging system will be presented and patients will be enlightened about the treatment they need to apply. A new staging system was developed in 2012, the amount of protein lost in the urine is also important in this system, but the old staging system is used here because it is more practical and understandable for the patients.
Permanent kidney disease staging
Stage Identification Creatinine clearance
(CrC) (ml/min)
– Increased risk ≥60
(risk factors +)
1 There is kidney damage, but CrC is normal or increased ≥90
2 There is kidney damage, slightly decreased CrC 60-89
3 Moderately decreased CrC 30-59
4 Severely decreased CrK 15-29
5 End-stage renal disease < 15
In the light of this information, you can calculate your creatinine clearance and the stage of your disease. To sum up, high creatinine does not mean dialysis, it is necessary not to interrupt the follow-ups in order not to be a dialysis patient/delay the onset if necessary and not be caught unprepared for preventable problems. As long as you take good care of your kidneys, they will take good care of you.
Suggested sources:
1. ‘How can I avoid being a dialysis patient?’ section named (www.tekinakpolat.com)
2. ‘So glad my blood pressure is out’, Doğan Kitap 2016.
3. How Can I Prevent Dialysis with High Urea Creatinine, 2016. For Download (www. tekinakpolat.com).
