The levels of creatinine in your urine and/or blood is measured with creatinine test. As part of your daily routine, your muscles produces a waste product called creatinine. Normally, creatinine that is filtered by your kidneys from the blood, is remove from the body through your urine. When the kidneys fail, less creatinine is seen in urine and it can accumulate in the blood. A possible kidney disease sign can be indicated if the creatinine level in blood and/or urine is abnormal.
In this article, we are going to discuss the different types of creatinine test for clearance, level and serum, and what it means for kidney function. We will equally discuss when to request for a creatinine test, possible risk involved with a creatinine test and how to manage them.
Alternative names: urine creatinine, serum creatinine, blood creatinine
What is the normal creatinine test level?
The normal creatinine levels turn to depend on height, race, age and gender.
When is a creatinine test required?
Creatinine test can be part of a routine urine/ blood test and is often used when a person has a non-specific medical condition or when your physician suspects that you are having kidney malfunction.
Kidney dysfunction Signs and symptoms
The signs and symptoms of kidney disease can include the following:
- Urinating problems, such as abnormal discharge when urinating, a burning sensation, or a change in how often you urinate.
- Pain in the middle of the back (hip), near the kidneys and under the ribs.
- Trouble sleeping, Fatigue, loss of appetite, or lack of concentration.
- Puffiness or swelling, especially around the ankles or eyes, wrists, face, thighs, or stomach.
- Brown, bloody, or Foamy urine.
- Decreased urine output.
Creatinine test is equally used to monitor kidney function while taking certain medications or monitor treatment for kidney disease.
How to prepare for creatinine test?
Your doctor may recommend that you temporarily stop taking some medications that may interfere with the creatinine test. These drugs include:
- Ranitidine, famotidine and cimetidine
- Antibiotics such as trimethoprim and cefoxitin
Tell your doctor if you are on any medication.
What can you expect with a creatinine test?
By inserting a needle into a vein in your arm, a member of your health care team will take a blood sample to be used for a serum creatinine test.
You must give a urine sample in the lab or collect the urine sample from your home within 24 hours and send it back to the lab for a urine creatinine test.
How to perform a creatinine test?
Health providers use a creatinine test to measure kidney function using two ways:
1. A Urine creatinine test:
Measuring the amount of creatinine in a urine sample collected over a 24-hour period can give an estimate of the Glomerular filtration rate. With this method, use a plastic container to store all of your urine for a day and then take it for analysis. Though this method may be necessary to diagnose some kidney diseases, it is impractical and not often used today.
2. A Blood Creatinine test.
From a single blood creatinine level that they enter into the formula, Clinicians can estimate GFR. Your age and gender are considered with a variety of formulas, while ethnicity or race might be considered in older formula. Lower estimated GFR is as a result of higher the blood creatinine level.
Blood creatinine test is for practical reasons, used much more frequently to estimate Glomerular filtration rate than the 24-hour collected urine creatinine test. However, for people with high muscle mass or significantly low muscle mass, urine collection may still being used.
Creatinine test results
Urine or Blood creatinine test results are interpreted and measured in several ways, including:
1. The serum creatinine level
Generally, creatinine that enters the bloodstream, is filtered out of it at a constant rate. The creatinine levels in blood should be relatively constant. Elevated creatinine levels can be an indication of a kidney malfunction.
Mg/dL (Milligrams of creatinine per deciliter of blood) is the expression for serum creatinine or micromoles/L (micromoles of creatinine per liter of blood). The typical serum creatinine range is:
- 0.59 to 1.04 mg/dL for adult females (52.2 to 91.9 micromol/L)
- 0.74 to 1.35 mg/dL for adult males (65.4 to 119.3 micromol/L)
2. GFR (Glomerular Filtration Rate)
An estimate of the glomerular filtration rate (rate at which the kidneys filter the blood), can be gotten from serum creatinine measurements. The GFR (glomerular filtration rate) may provide a more accurate indication of kidney function, due to the variability of serum creatinine from person to person.
Serum creatinine and factors like as age and gender are taken into account in the formula used to calculate the GFR. A kidney disease can be indicated with a GFR less than 60. The range below 60 can be used to monitor disease progression and treatment.
What is creatinine clearance?
A measure of how well the kidneys filters creatinine from the bloodstream to excrete it in the urine is called creatinine clearance.
Usually, creatinine levels in a 24-hour urine sample and a serum sample collected during the same period can give creatinine clearance measurements. Shorter time periods can however be used for urine samples. It is essential to accurately time and collect the urine sample for the creatinine test.
Ml/min/BSA (milliliters of creatinine per minute and body surface area) is the expression for creatinine clearance. The typical range is 77-160 mL/min/BSA, for men ages 19 to 75years.
Typical creatinine clearance in women by age range are:
- 78 to 161 mL/min/BSA: 18 to 29 years
- 72-154 mL/min/BSA: 30 to 39 years
- 67-146 mL/min/BSA: 40 to 49 years
- 62-139 mL/min/BSA: 50 to 59 years
- 56-131 mL/min/BSA: 60 to 72 years
There is no standard measure for the elderly.
Lower than the general range results may be a sign a condition that affects blood flow to the kidneys or of kidney malfunction.
Albumin/Creatinine ratio
The albumin/creatinine ratio gives another urine creatinine count interpretation. Blood contains a protein called albumin. There should be no or little urine albumin, given that a healthy kidneys usually do not filter albumin out from the blood.
A description of the amount of albumin contained in urine sample Vs the the creatinine content gives us the albumin/creatinine ratio. Results are given as the number of mg (milligrams) of urine albumin per gram (g) of urine creatinine. Healthy kidney results are:
- Less than 17 mg per g for adult males
- Less than 25 mg per g for adult women
A sign of kidney disease can be indicated with a greater than average results. Specifically, the findings could indicate a diabetes complication called diabetic disease of the kidney, or diabetic nephropathy.
Risk associated to a creatinine test
Low risk of blood draw. The arteries and veins size varies from one body side to another and from person to person. It can be hard to draw blood from some individuals than from other individuals.
More risks factors with having your blood drawn are minor, but may include:
- Heavy bleeding
- Blood clot under your skin (Hematoma)
- small risk with skin puncture (Infection)
- Dizziness or fainting
- Several punctures to find the vein.
Message from Big Man Lab: Since herbs, over-the-counter drugs (especially for minor headaches, aches and pains), and supplements can affect the kidneys, they should not be taken without first consulting a physician. Until their GFR is very low (for example, less than 10) most people don't need dialysis. However, it is important to act early to preserve as much of it as possible, since kidney function naturally drops with age.
