What is Creatinine test?

Creatinine test is ordered to evaluate the health of kidneys, detect kidney disease and monitor the treatment provided for kidney disease.

Creatinine is generated as a waste product in the body and is almost fully removed by healthy kidneys. It starts to build up in bloodstream in case of kidney dysfunction. So, measuring creatinine levels in the blood can help doctors determine kidney function.

This test is also known as creat, blood creatinine and serum creatinine.

  1. Why is Creatinine test performed?
  2. How do you prepare for Creatinine test?
  3. How is Creatinine test performed?
  4. Creatinine test results and normal range

Creatinine test is often ordered as part of routine medical tests that are conducted to check for overall health. It is also suggested when signs and symptoms of kidney disease are observed in individuals, such as:

Older people; people with diabetes or those a history of kidney diseases; and American Indian, Asian, African American, Pacific Islander, and Hispanic people are at a high risk of kidney disease.

This test is also ordered for people who are being treated for kidney disease to check the effectiveness of the treatment.

You might be instructed to fast overnight or avoid eating cooked meat before the test.

The doctor might also as you to temporarily discontinue certain medications that could increase creatinine levels, such as ranitidine, cimetidine, famotidine, and some antibiotics like trimethoprim.

A phlebotomist or a technician will use a needle to collect a blood sample from a vein in your hand. It is best to inform the technician if you feel nervous about needles. The following process takes place while collecting a blood sample:

  • You will be asked to lie down or be seated and make a fist    
  • The technician will tie a tourniquet around your arm    
  • Once a vein is visible, the technician will disinfect the area and insert a needle into it    
  • After drawing enough blood, he/she will take out the needle and place an adhesive bandage at the site of withdrawal    
  • You will be asked to press on the injection site firmly to stop the bleeding.

Minor risks involved with the blood test are:

  • Feeling lightheaded
  • Fainting
  • Infection at the site of blood withdrawal
  • Excessive bleeding
  • Haematoma (accumulation of blood under the skin)

Creatinine test results might vary according to gender, age, health history of the individual, and the method used for the test. It is best that you consult your doctor for discussion and proper interpretation of test results.

Normal results:

Normal creatinine levels depend on the amount of muscle mass you have. Based on age the normal range of creatinine levels in the blood are as follows:

  • Children under 3 years of age: 0.3 to 0.7 mg/dL
  • Children aged 3 to 18 years: 0.5 to 1.0 mg/dL
  • Adult females: 0.6 to 1.1 mg/dL
  • Adult males: 0.9 to 1.3 mg/dL

If the doctor orders a creatinine clearance test, creatinine levels in 24-hour urine collection are evaluated along with the creatinine blood test.

Abnormal results:

Lower-than-normal creatinine levels indicate the possibility of the following conditions:

Higher-than-normal creatinine levels indicate the possibility of:

  • Kidney disease
  • Shock
  • Muscle disease like rhabdomyolysis (breakdown of muscle fibres)
  • An overactive thyroid gland
  • Congestive heart failure (a condition in which the heart does not pump blood as efficiently as it should)
  • Diabetes
  • Dehydration
  • Problems during pregnancy, such as preeclampsia (high blood pressure) or eclampsia (seizures)
  • Blockage in the urinary tract

The test might be ordered for other conditions as well, such as diabetes, high blood pressure or medicine overdose.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.  

References

  1. Sunil Nair et al. Effect of a Cooked Meat Meal on Serum Creatinine and Estimated Glomerular Filtration Rate in Diabetes-Related Kidney Disease. Diabetes Care 2014 Feb; 37(2): 483-487. https://doi.org/10.2337/dc13-1770
  2. MedlinePlus Medical Encyclopedia: US National Library of Medicine; Creatinine blood test
  3. Pagana, K. D., Pagana, T. J., and Pagana, T. N. (©, 2015). Mosby's Diagnostic & Laboratory Test Reference 12th Edition: Mosby, Inc., Saint Louis, MO. Pp 312-314.
  4. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; Creatinine (Blood)
  5. Inker LA, Fan L, Levey AS. Assessment of renal function. In: Johnson RJ, Feehally J, Floege J, eds. Comprehensive Clinical Nephrology. 5th ed. Philadelphia, PA: Elsevier Saunders; 2015: chap 3.
  6. Landry DW, Bazari H. Approach to the patient with renal disease. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016: chap 114.
  7. Chernecky CC, Berger BJ. Creatinine - serum. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:399.
  8. Johns Hopkins Medicine [Internet]. The Johns Hopkins University, The Johns Hopkins Hospital, and Johns Hopkins Health System; Blood Test
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