Can impaired renal function, as indicated by elevated creatinine and low estimated glomerular filtration rate (eGFR), in a 70-year-old female be caused by dehydration?

From the Guidelines

Dehydration can indeed cause impaired renal function, as indicated by elevated creatinine and low estimated glomerular filtration rate (eGFR), in a 70-year-old female, due to reduced blood volume and blood pressure leading to decreased blood flow to the kidneys, resulting in pre-renal acute kidney injury. This condition is often multifactorial, but prerenal factors, including hypovolemia, are a common cause of acute kidney injury (AKI) 1. According to the American College of Radiology, AKI is defined as an increase in creatinine by 0.3 mg/dL within 48 hours or an increase in serum creatinine to 1.5 times baseline, and dehydration can lead to this increase by reducing kidney perfusion 1.

The patient's laboratory results, including elevated creatinine (1.08) and low eGFR (55), are consistent with impaired renal function. The BUN/creatinine ratio is normal (17), which suggests that the cause of the impaired renal function may be prerenal, such as dehydration, rather than renal or postrenal 1.

Key points to consider in this patient's case include:

• Dehydration can lead to pre-renal AKI, which is reversible with proper fluid replacement
• Elderly patients are at higher risk of dehydration due to diminished thirst sensation and reduced reserve capacity of the kidneys
• Treatment involves careful rehydration with intravenous or oral fluids, monitoring of fluid intake and urine output, and repeat kidney function tests
• Complete recovery of renal function may take longer in elderly patients, typically within 24-72 hours with appropriate fluid replacement 1.

In this case, it is essential to prioritize rehydration and monitoring of the patient's renal function to prevent further deterioration and promote recovery. The patient's sodium, potassium, chloride, and carbon dioxide levels are within normal limits, which suggests that the dehydration is not severe, but still requires prompt attention to prevent worsening of renal function 1.

From the Research

Impaired Renal Function and Dehydration

• Impaired renal function, as indicated by elevated creatinine and low estimated glomerular filtration rate (eGFR), in a 70-year-old female can be caused by various factors, including dehydration 2.
• Dehydration is known to be associated with acute renal dysfunction, and recent studies have suggested that recurrent dehydration may lead to permanent kidney damage 2.
• The mechanisms by which dehydration may lead to chronic kidney disease include the effects of vasopressin on the kidney, the activation of the aldose reductase-fructokinase pathway, and the effects of chronic hyperuricemia 2.

Role of Dehydration in Renal Function

• Mild dehydration may be a risk factor in the progression of all types of chronic kidney diseases, and increasing hydration, particularly with water, may actually prevent CKD 2.
• Dehydration can lead to a decrease in renal blood flow, which can cause a decrease in glomerular filtration rate (GFR) and an increase in serum creatinine levels 3.
• The diagnosis of acute kidney injury (AKI) remains fundamentally dependent on the serum creatinine level and urine output, both of which are considered late markers of AKI 3.

Other Factors Affecting Renal Function

• Nonsteroidal anti-inflammatory drugs (NSAIDs) are nephrotoxic and can cause both acute and chronic effects on kidney function 4.
• The use of NSAIDs can lead to a decrease in renal function, particularly in patients with pre-existing kidney disease 4.
• Other medications, such as angiotensin-converting-enzyme inhibitors, angiotensin-receptor blockers, and diuretics, can also affect renal function and increase the risk of acute kidney injury 5, 6.

Monitoring Renal Function

• Systematic measurement of urine creatinine can be useful in monitoring renal function, particularly in patients at risk of acute kidney injury 3.
• Changes in urine creatinine can precede changes in blood creatinine, allowing for earlier detection of renal dysfunction 3.
• The use of estimated GFR (eGFR) reporting can help identify patients at risk of kidney disease and improve prescribing practices, particularly with regards to nephrotoxic medications 4.