From the Guidelines
The elevated BUN with normal creatinine and a GFR of 62 suggests pre-renal azotemia, which is often caused by dehydration or decreased renal perfusion, and the immediate recommendation is to increase fluid intake, preferably oral hydration with water or electrolyte solutions if tolerated. According to the KDIGO CKD definition, a GFR of 62 falls into the G2 category, indicating mildly decreased renal function 1. The patient's laboratory results are consistent with pre-renal azotemia, characterized by an elevated BUN/creatinine ratio (>20:1), which is indicative of dehydration or reduced renal perfusion rather than intrinsic kidney damage.
Key considerations in managing this patient include:
- Investigating underlying causes, such as medication review for drugs that affect kidney function (NSAIDs, diuretics, ACE inhibitors), assessment for heart failure, or other conditions reducing renal blood flow
- Ensuring proper hydration to improve renal perfusion and reduce urea reabsorption
- Monitoring renal function closely, with follow-up testing in 1-2 weeks to ensure improvement
- Recognizing that the GFR of 62 indicates mild kidney function reduction (Stage 2 CKD), which may improve with proper hydration and management of underlying causes, as emphasized in the study on renal function monitoring in heart failure 1.
The importance of frequent and regular monitoring of renal function is highlighted in the study, although there is no evidence-based gold standard for optimal frequency 1. In this case, prioritizing the patient's hydration status and addressing potential underlying causes is crucial to improve renal function and prevent further decline.
From the Research
Patient Profile
- Elevated BUN (Blood Urea Nitrogen)
- Normal CR (Creatinine)
- GFR (Glomerular Filtration Rate) of 62
Relevant Studies
- A study from 1998 2 found that acute renal failure associated with ACE inhibitors is likely to occur in many patients without renal artery stenosis after unexpected dehydration, especially in older patients with congestive heart failure.
- A five-year comparison study from 2006 3 found that the renal protective effects of ACE inhibitors and ARBs were similar, but the decline in GFR was significantly greater in patients treated with ARBs after 4 years.
- A cross-sectional study from 2025 4 found that ARBs and ACEIs were insufficiently prescribed for patients with hypertension associated with CKD with proteinuria, despite guideline recommendations.
- A study from 2021 5 found that ACE inhibitor/ARB underutilization represents a significant gap in preventive care delivery for adults with hypertension and albuminuria.
- A study from 2019 6 found that rates of ACE/ARB use among those with impaired kidney function in the United States increased from 1999 to 2014, but appeared to plateau after 2003.
Key Findings
- Elevated BUN with normal CR and GFR of 62 may indicate dehydration or other conditions that affect renal function.
- ACE inhibitors and ARBs may be beneficial in patients with hypertension and impaired kidney function, but their use may be insufficient in certain populations.
- Further evaluation and monitoring of renal function and overall health are necessary to determine the best course of treatment.