From the Guidelines
Normal creatinine levels in adults typically range from 0.7 to 1.3 mg/dL for men and 0.6 to 1.1 mg/dL for women. These values may vary slightly between different laboratories 1. Creatinine is a waste product produced by muscle metabolism and is filtered out of the blood by the kidneys, serving as an important marker of kidney function.
Key Factors Affecting Creatinine Levels
- Muscle mass: More muscle typically means higher baseline creatinine
- Age: Levels may increase slightly with age
- Diet: High protein intake, particularly meat consumption, can temporarily increase levels
- Certain medications
- Hydration status It's essential to note that creatinine levels can be influenced by various factors, including impaired hepatic production of creatine, reduced muscle mass, female sex, and renal tubular secretion of creatinine 1. Additionally, hyperbilirubinemia can result in inaccurate measurement of serum creatinine by calorimetric methods.
Clinical Significance of Creatinine Levels
Regular monitoring of creatinine levels is crucial for individuals with kidney disease, diabetes, high blood pressure, or those taking medications that may affect kidney function 1. Significant deviations from normal ranges warrant medical attention as they could indicate kidney problems requiring treatment. The Kidney Disease: Improving Global Outcomes organization clinical practice guidelines define acute kidney injury (AKI) by either an increase in serum creatinine by 0.3 mg/dL within 48 hours, an increase in serum creatinine to 1.5-fold from baseline that presumably has occurred within the previous 7 days, or urine volume <0.5 mL/kg/h for 6 hours 1.
From the Research
Normal Creatinine Levels and Angiotensin-Converting Enzyme Inhibitors/Angiotensin Receptor Blockers
- The impact of angiotensin-converting enzyme inhibitors (ACE-I) and angiotensin receptor blockers (ARB) on renal function, particularly in relation to normal creatinine levels, has been investigated in several studies 2, 3, 4, 5, 6.
- A study published in the Journal of cardiovascular pharmacology and therapeutics found that ACE-I/ARB withdrawal was not associated with improved renal function at 72 hours in patients with type 1 cardiorenal syndrome 2.
- Another study published in the American journal of nephrology found that acute exposure to ACEI/ARB was not associated with persistent acute kidney disease at the time of first clinic visit 3.
- A meta-analysis published in BMC nephrology found that ACEI/ARB therapy significantly slowed the rate of decline in residual renal function in dialysis patients 4.
- A systematic review and meta-analysis published in Frontiers in pharmacology found that exposure to ACEI/ARB after acute kidney injury was associated with lower risks of all-cause mortality, recurrent AKI, and progression to incident CKD 5.
- A retrospective individual participant-level meta-analysis published in Annals of internal medicine found that initiation of ACEI or ARB therapy protected against kidney failure with replacement therapy, but not death, in people with advanced CKD 6.
Key Findings
- ACEI/ARB therapy may not improve renal function in the short term, but may have long-term benefits in reducing the risk of kidney failure and mortality 2, 5, 6.
- The use of ACEI/ARB in patients with acute kidney injury or advanced CKD requires careful consideration of the potential benefits and risks, including the risk of hyperkalemia 3, 5.
- Further research is needed to fully understand the effects of ACEI/ARB on renal function and outcomes in different patient populations 2, 4, 6.