When there are very general symptoms in the body, which may be due to various diseases or afflictions, the physician will order tests for what he suspects may be the cause. The creatinine test is one of them. This can give us many indications about a patient’s state of health and help us to find out what is wrong in order to treat him/her.
Today we will talk about the effects of, specifically, low creatinine, what causes it and much more.
What is creatinine?
Creatinine is a substance produced by the union of creatine and creatine phosphate. It is the consequence of muscular metabolic processes. The kidneys are responsible for absorbing this substance in its final phase and eliminating it in the urine. One of the problems of uncontrolled creatinine levels is kidney problems.
As mentioned above, it is the kidneys that absorb and manage this substance, so testing creatinine can help us to find out if the kidneys are functioning properly. It is usually ordered together with another kidney test, the blood urea nitrogen (BUN) test. In this way a complete metabolic panel can be obtained, a group of tests whose purpose is to provide information about different organs, apparatuses and systems of the body. It is usually included in routine checkups.
Creatinine can be measured in both blood and urine. If by blood test, serum creatinine can help diagnose and monitor acute and chronic kidney disease and estimate the glomerular filtration rate or volume of filtered fluid. A urinalysis can also show whether these organs, which are responsible for the cleansing and balancing functions of the blood, are functioning properly.
When to order a creatinine test?
The creatinine test may be requested, in addition to a routine control, when there is specific discomfort or when the physician suspects a possible kidney disease. Some of its symptoms are:
- Tiredness, difficulty concentrating, lack of appetite, sleep disorders.
- Foamy, bloody or brown urine.
- Decrease in the amount of urine.
- Urination problems (burning or presence of abnormal secretions or rhythm alterations), and irregular urination (especially at night).
- Lumbar and flank pain, below the ribs, near the kidneys.
The creatinine test is also usually requested if the patient has some risk factors for kidney disease. The risk of developing this type of disease increases if you have type 1 or 2 diabetes, high blood pressure or a family history of kidney disease.
The blood creatinine test may be ordered along with blood urea and urine albumin. It is also usually ordered before a CT scan, during some treatments and before and after dialysis. In this way, the effectiveness of the treatment can be evaluated.
How are the samples obtained?
In the case of needing for a blood creatinine test, a medical professional will take a blood sample from a vein in your arm. The patient may experience some mild discomfort from the needle stick, but the procedure usually lasts less than five minutes and the pain passes very quickly.
If a urine creatinine test is needed, the patient should collect all urine for 24 hours. The physician will give you instructions on how to collect and store the samples. Normally, the procedure is as follows:
- The patient will urinate in the morning and note the time.
- During the next 24 hours, you should collect samples of all urine in the container provided and store them in the refrigerator.
- The physician will provide instructions for taking or sending the specimen container to the physician or laboratory.
What can be expected from the results of the analysis?
Blood or urine creatinine results can be interpreted in several ways, including the following:
Serum creatinine level. Creatinine enters the bloodstream and is filtered at a normally constant rate. The amount of this substance in the blood should be relatively stable. An elevated creatinine level may be a symptom of poor kidney function. Serum creatinine is expressed in milligrams of creatinine per deciliter of blood (mg/dL) or micromoles of creatinine per liter of blood (micromoles/L). The range is:
- From 0.74 to 1.35 mg/dL (65.4 to 119.3 micromoles/L) for adult men.
- From 0.59 to 1.04 mg/dL (52.2 to 91.9 micromoles/L) for adult women.
Glomerular filtration rate. Measurement of serum creatinine can also be used to assess the rate at which the kidneys filter the blood (glomerular filtration rate). As serum creatinine varies from person to person, a glomerular filtration rate provides a more accurate reading of renal function.
The glomerular filtration rate formula takes into consideration the serum creatinine count and other factors, such as age and sex. If the glomerular filtration rate is below 60 it indicates a altered glomerular filtration rate. The range of scores below 60 is used to monitor treatment and disease progression.
Creatinine clearance. It measures the kidneys’ ability to filter creatinine from the bloodstream and expel it in the urine. Clearance is determined by measuring creatinine in a urine sample collected with the measurements explained above. Shorter time periods can also be applied for urine samples. Whichever way it is done, it is essential that the timing and collection of the urine sample be as indicated by the physician or specialist.
Creatinine clearance is measured in milliliters of creatinine per minute per body surface area (mL/min/ASC). Normal levels in men are 77 to 160 mL/min/ASC (aged 19 to 75 years). The normal range in women (by age) is as follows:
- 78 to 161 mL/min/ASC (aged 18 to 29 years).
- 72 to 154 mL/min/ASC (30 to 39 years).
- 67 to 146 mL/min/ASC (40 to 49 years).
- 62 to 139 mL/min/ASC (aged 50 to 59 years).
- 56 to 131 mL/min/ASC (aged 60 to 72 years).
No baseline measurements have been determined for older adults.
A result below the normal range in the patient’s appropriate group may mean poor kidney function or conditions that vary blood flow to the kidneys.
Albumin-creatinine ratio. It is another interpretation of the urine creatinine count due to albumin, a blood protein. A healthy kidney does not filter it from the blood, so if we see albumin in the urine, there should be little or no albumin present.
The albumin-creatinine ratio indicates the amount of albumin in a urine sample in relation to the amount of creatinine. The results are measured in milligrams (mg) of albumin per gram (g) of creatinine. If the kidneys are healthy it should give the following result:
- Less than 17 mg/g in adult males.
- Less than 25 mg/g in adult women.
If the result is higher than these figures, we could be talking about renal impairment.. It could also indicate a complication derived from diabetic nephropathy.
The physician will be in charge of transmitting the results and assisting the patient in any doubt about the situation in order to elaborate a treatment plan.
What does it mean to have low creatinine?
Los valores normales de creatinina varían entre 0,6 y 1,1 mg/dL en las mujeres y 0,7 y 1,3 mg/dL en los hombres. Any value below these levels will be considered low creatinine. The difference in measurement between men and women is due to the fact that creatinine is produced in the body depending on the level of muscle mass. It is normal for men to have higher blood creatinine levels than women, as they tend to have more developed muscles.
However, the ‘normal’ values for creatinine levels in the blood may vary depending on the laboratory and the method they use for analysis. Since creatinine is produced in the muscles, its concentration can vary as a person develops. Therefore, reference values may also change over time:
- Newborns: 0.60 to 1.30 mg/dl.
- Infants between 1-6 months: 0.40 to 0.60 mg/dl.
- Children and adolescents (from 1 to 18 years old): 0.40 to 0.90 mg/dl.
It is more common to have high creatinine than low creatinine. However, it may be the case that it is below normal values. This fact may be related to a reduction in muscle mass or be a warning of the existence of a disease to be taken into account (myasthenia gravis).
Its main symptoms are muscle weakness and tissue loss. It is very common for women to have low creatinine levels during pregnancy. In this case, the levels are not due to disease.
Its analysis will allow health professionals to assign a specific treatment to the patient. However, to increase creatinine can also be incorporated into the diet:
- Proteins (red meat, fish, eggs or cheese).
- Foods rich in potassium (potatoes and spinach).
If you suspect a possible low creatinine level, it is best to see a doctor to evaluate possible causes and set guidelines to follow along with a treatment. If you need it, you can always count on AmbarLab for any laboratory analysis. We offer more than 3,000 laboratory tests… If you have any doubts or need to ask a question, please contact us and a member of the team will answer all your questions.