What is a creatinine level?

Creatinine Blood Test Guide - Normal Values & Kidney Disease Insight

Creatinine level refers to the amount of creatinine, a waste product from metabolism, specifically in the blood or urine. Doctors perform this test to assess kidney function, as creatinine is predominantly filtered in the kidneys and gets excreted in urine. Elevated levels can indicate potential kidney problems.

Why is creatinine important?

Creatinine level in the blood or urine determines how well your kidneys are performing and functioning. Healthy kidneys efficiently filter creatinine from the blood and excrete it in the urine. Thus, an increase in its levels can indicate that the kidneys may not be filtering properly. 

Apart from this, it has other functions, which are as follows:

• Early Warning Signs: Elevated creatinine levels can be an indicator of kidney dysfunction or damage. As there is a decline in kidney function, the kidneys may not be able to remove this efficiently, leading to its buildup in your blood.
• Management of Chronic Kidney Disease: It helps healthcare providers to make decisions regarding treatment options. Higher levels of creatinine in your blood signify reduced kidney function, whereas lower levels of creatinine signify increased kidney function. Apart from this, it also measures and monitors the glomerular filtration rate to determine the stages of CKD.
• Creatinine Clearance Test: The creatinine clearance test measures how quickly your kidneys filter waste products, including creatinine, from the blood. Lower levels of creatinine clearance indicate serious kidney problems. A creatinine clearance level below 30 ml/min suggests renal dysfunction.
   

What are the normal creatinine levels?

Normal creatinine levels are different in men and women, and these results differ slightly in various laboratories.

• Men: Typically ranges between 0.7 mg/dL and 1.3 mg/dL (6.19 to 114.9 µmol/L).
• Women: Generally ranges between 0.6 mg/dL and 1.1 mg/dL (53 to 97.2 µmol/L). 
   

What Does a Low Creatinine Level Signify?

Low creatinine levels are less common than high levels and can indicate certain things. However, they are not generally major concerns. Several possible causes can cause low creatinine levels, including:

• Reduced Muscle Mass: Creatinine is a waste product of muscle metabolism. Thus, lower creatinine levels may suggest lower muscle mass. This is more common in older adults or individuals with chronic illnesses or nerve disorders.
• Malnutrition: Low creatinine levels can also be linked to insufficient protein intake or malnutrition, which can affect muscle mass and metabolism. Lesser muscle metabolism leads to lower levels of creatinine.
• Pregnancy: Creatinine levels fluctuate during pregnancy due to significant changes in blood volume and kidney function. Increased blood flow to the kidneys results in increased glomerular filtration rate (GFR), and reduced oncotic pressure contributes to lower creatinine levels.  
• Liver Disease: Creatinine levels can fluctuate in individuals with liver disease due to a combination of factors that affect both creatinine production and excretion. Impaired liver function leads to decreased creatinine production, while malnutrition and muscle wasting in cirrhosis further reduce creatinine levels.
• Certain Medications: Certain medications, such as antibiotics, proton pump inhibitors, cimetidine, and salicylates, can lower the creatinine level in your body. Frequent usage of these medicines can reduce the serum creatinine level. Thus, it is mandatory to check the patient's current medications.
   

Though a low creatinine level can signify certain conditions, it is still less concerning than high creatinine levels. High levels indicate serious kidney problems, as they accumulate in the body due to impaired kidney function.