From the Guidelines
A borderline estimated glomerular filtration rate (eGFR) and creatinine in a patient who has increased hydration can be caused by several factors, including early kidney dysfunction, medication side effects, dehydration despite recent increased fluid intake, underlying medical conditions, age-related kidney function decline, or muscle mass variations affecting creatinine levels, as noted in studies such as 1 and 1. The most common causes of borderline eGFR and creatinine include:
- Early kidney dysfunction
- Medication side effects (particularly NSAIDs, ACE inhibitors, ARBs, certain antibiotics like aminoglycosides, and some chemotherapy drugs)
- Dehydration despite recent increased fluid intake
- Underlying medical conditions (such as diabetes, hypertension, or heart failure)
- Age-related kidney function decline
- Muscle mass variations affecting creatinine levels Increased hydration alone may not fully correct these values if an underlying issue exists. The patient should continue adequate hydration (approximately 2-3 liters of water daily) while avoiding nephrotoxic medications when possible, as suggested by 1 and 1. Laboratory values should be rechecked in 1-2 weeks to monitor trends. If values remain abnormal or worsen, further evaluation including urinalysis, urine protein measurement, and renal ultrasound may be necessary to identify the underlying cause, as recommended by 1 and 1. Kidney function naturally declines with age, and creatinine levels are influenced by muscle mass, making interpretation sometimes challenging in very muscular or frail individuals, as discussed in 1 and 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Potential Causes of Borderline EGFR and Creatinine
- Increased hydration status may not be the sole cause of borderline EGFR and creatinine levels, as other factors such as nonsteroidal anti-inflammatory drug (NSAID) use 2 and underlying kidney disease 3, 4, 5 can also impact these values.
- NSAID use has been shown to decrease renal function, and stopping NSAID treatment can lead to significant improvements in estimated renal function 2.
- Metabolic changes, such as anaemia, hyperkalaemia, and uraemia, can occur at earlier stages of kidney disease than previously thought, and may be present in patients with borderline EGFR and creatinine levels 3.
- A systematic approach to diagnosing and managing renal failure, including history, physical examination, and baseline tests, can help identify the underlying cause of elevated creatinine levels 4.
- Even minimal renal insufficiency, as indicated by borderline EGFR and creatinine levels, can have a negative impact on patient outcomes, particularly in those with multiple myeloma treated with autologous stem cell transplant 5.
Importance of Accurate GFR Assessment
- Accurate assessment of GFR is crucial for diagnosing, staging, and managing chronic kidney disease, as well as determining drug dosages and prognosis 6.
- Estimated GFR (eGFR) equations based on serum creatinine concentrations are commonly used, but may not always provide an accurate assessment of GFR, and confirmatory tests such as cystatin C-based equations or urinary clearance of exogenous filtration markers may be necessary 6.