The question asks us to identify the primary biomarker used for the detection of acute renal failure from the given options. Let's analyze each option:

1. Glomerular filtration rate (GFR): This is the best overall indicator of kidney function. It measures how well the kidneys are filtering blood, specifically how much blood is filtered per minute. It is a critical measure to diagnose and track kidney performance, especially in acute renal failure.
2. Serum sodium: While serum sodium levels can be affected by kidney function, they are not specific indicators of acute renal failure.
3. Blood urea: Blood urea nitrogen (BUN) levels can indicate kidney function, but they can be influenced by many other factors such as dietary protein intake and hydration status, making them less specific than GFR.
4. Serum creatinine: Serum creatinine is another common test to assess kidney function. However, its levels can be influenced by muscle mass and dietary intake, so it may not always accurately reflect acute changes in kidney function.

The most specific and reliable marker for detecting acute renal failure is the Glomerular filtration rate (GFR), as it directly measures the kidneys' filtering capacity. Hence, the correct answer to this question is Glomerular filtration rate.

Conclusion: The primary biomarker for the detection of acute renal failure is the Glomerular filtration rate (option 1), making it the most suitable choice among the options provided.