What causes a sudden drop in Glomerular Filtration Rate (GFR), indicating Impaired renal function?

From the Guidelines

A sudden drop in glomerular filtration rate (GFR) is a medical emergency that requires immediate attention, as it may indicate acute kidney injury (AKI), which can lead to increased morbidity and mortality if not promptly addressed. The most recent and highest quality study on this topic is from 2021, which defines AKI as an increase in creatinine by 0.3 mg/dL within 48 hours or an increase in serum creatinine to 1.5 times baseline (within prior 7 days) or urine volume 0.5 mL/kg/hr for 6 hours 1. Common causes of AKI include dehydration, certain medications (especially NSAIDs like ibuprofen, ACE inhibitors, ARBs, and some antibiotics), contrast dye from imaging studies, severe infections, or urinary obstruction.

Key Considerations

• AKI is often multifactorial but generally categorized as prerenal, renal, or postrenal, with prerenal and renal etiologies far outweighing obstruction as a cause of AKI, accounting for >97% of AKI 1.
• Evaluation of the patient with AKI includes a thorough history, physical examination, and laboratory analysis of blood (for serum creatinine, blood urea nitrogen, complete blood count, and differential) and urine (microscopy for casts and epithelial cells, chemistry, and biomarkers) 1.
• Treatment depends on the underlying cause but often includes stopping nephrotoxic medications, ensuring adequate hydration, and treating any infections, with hospitalization necessary in severe cases.

Recommendations

• Contact your healthcare provider right away if you experience a sudden drop in GFR, as prompt medical evaluation is essential to prevent permanent kidney damage.
• Your doctor will likely order additional blood tests to check creatinine, BUN, and electrolytes, along with urinalysis to look for protein or blood.
• Do not attempt to self-diagnose or treat this condition, as proper medical evaluation and treatment are critical to improving outcomes and reducing morbidity and mortality. According to a study from 2001, ACE inhibitors may induce ARF in patients with high-grade bilateral renal artery stenosis or stenosis of a dominant or a single kidney, as in renal transplant recipients; in patients with atherosclerotic disease in smaller preglomerular vessels; or in patients with afferent arteriolar narrowing due to hypertension or chronic cyclosporine use 1. However, the most recent and highest quality study from 2021 should be prioritized when making clinical decisions 1.

From the FDA Drug Label

In patients with severe congestive heart failure whose renal function may depend on the activity of the renin-angiotensin-aldosterone system, treatment with angiotensin converting enzyme inhibitors, including lisinopril, may be associated with oliguria and/or progressive azotemia and rarely with acute renal failure and/or death In hypertensive patients with unilateral or bilateral renal artery stenosis, increases in blood urea nitrogen and serum creatinine may occur. Evaluation of patients with hypertension, heart failure, or myocardial infarction should always include assessment of renal function. If renal dysfunction develops during treatment with lisinopril (serum creatinine concentration exceeding 3 mg/dL or a doubling from the pretreatment value) then the physician should consider withdrawal of lisinopril.

GFR suddenly dropped:

• The use of ACE inhibitors, including lisinopril, may be associated with a sudden drop in GFR, especially in patients with pre-existing renal impairment or those with renal artery stenosis.
• Patients with severe congestive heart failure, unilateral or bilateral renal artery stenosis, or those with pre-existing renal impairment are at higher risk of developing renal dysfunction.
• If a sudden drop in GFR occurs, the physician should consider withdrawal of lisinopril and assess renal function 2.

From the Research

Definition and Classification of Acute Kidney Injury

• Acute kidney injury (AKI) is characterized by a rapid decline in glomerular filtration rate (GFR) and accumulation of metabolic waste products 3, 4, 5, 6.
• AKI is classified according to the RIFLE criteria, which determines the level of renal dysfunction based on changes in serum creatinine or urine output 3.
• The severity of AKI is categorized based on urine output and elevations in creatinine level 4.

Causes and Risk Factors of Acute Kidney Injury

• AKI can be caused by prerenal, intrinsic renal, and postrenal factors 4, 6.
• The use of certain medications, such as aminoglycosides, can increase the risk of AKI, even in patients without prior chronic kidney disease 7.
• Low serum albumin and hemoglobin levels can also increase the risk of AKI episodes 7.

Management and Treatment of Acute Kidney Injury

• General management principles for AKI include determination of volume status, fluid resuscitation, treatment of volume overload with diuretics, and discontinuation of nephrotoxic medications 4.
• Conservative management should be attempted first, and renal replacement therapy or hemodialysis can be used if conservative management fails 5.
• Accurate diagnosis of the underlying cause of AKI is key to successful management, and may involve a focused history and physical examination, serum and urine electrolyte measurements, and renal ultrasonography 4.