Lactated Ringer's vs Normal Saline for Elevated CK Levels
Yes, use Lactated Ringer's (LR) instead of Normal Saline (NS) for fluid resuscitation in patients with elevated creatine kinase levels. Balanced crystalloids like LR are the preferred first-line fluid for most resuscitation scenarios and offer significant advantages over NS, particularly in protecting kidney function—a critical concern when CK levels are elevated 1.
Primary Recommendation
For patients requiring fluid resuscitation with elevated CK, administer LR as your initial crystalloid of choice 1. The evidence strongly supports balanced crystalloids over NS across multiple clinical contexts, with particular relevance to renal protection 1.
Key Advantages of LR Over NS
Renal Protection
- LR reduces the risk of acute kidney injury and need for renal replacement therapy compared to NS 1. The landmark SMART trial (n=15,802 critically ill patients) demonstrated lower rates of major adverse kidney events with balanced crystalloids versus saline 1.
- The SALT trial showed lower 30-day in-hospital mortality and decreased incidence of renal replacement therapy with balanced crystalloids 1.
- In patients with pre-existing chronic kidney disease and prerenal AKI, LR showed better acid-base balance improvement compared to NS 2.
Metabolic Benefits
- LR significantly reduces hyperchloremic metabolic acidosis, a common complication of large-volume NS resuscitation 1, 3.
- LR contains near-physiological electrolyte concentrations with lower chloride content (109 mmol/L) compared to NS (154 mmol/L) 1.
- Studies in DKA patients showed faster resolution times with LR versus NS (13 vs 17 hours, P=0.02) 4.
Addressing the Potassium Concern
The potassium content in LR (4 mmol/L) should not deter its use, even in patients with renal impairment:
- A retrospective study of 293 patients with eGFR <30 ml/min/1.73m² receiving ≥500 ml of LR found no independent association between LR use and development of hyperkalemia 5.
- Only 5% developed de-novo hyperkalemia, with no correlation to LR volume administered 5.
- In kidney transplant recipients, LR was associated with LESS hyperkalemia than NS (0% vs 19%, P=0.05) 6.
- The small potassium content is not a contraindication in most patients 7.
Clinical Implementation
Volume Considerations
- If NS must be used for specific reasons, limit to 1-1.5 L maximum 1.
- Volume and rate should be guided by frequent hemodynamic reassessment to avoid fluid overload 7.
Special Populations
- Exception: Use NS rather than LR in traumatic brain injury patients 1.
- For hemorrhagic shock, European guidelines recommend either NS or balanced crystalloids, but balanced solutions are preferred to avoid chloride-related complications 8.
Supporting Evidence Quality
The recommendation is based on:
- Multiple high-quality guidelines from 2022-2025 8, 1, 7
- Large RCTs including the SMART and SALT trials 1
- Consistent findings across diverse patient populations including DKA 4, 3, CKD 2, and transplant recipients 6
The evidence consistently demonstrates that LR provides superior renal protection and metabolic stability compared to NS, making it the optimal choice for patients with elevated CK levels who are at risk for rhabdomyolysis-induced acute kidney injury 1, 5.