From the Research
A BUN level of 4 mg/dL is below the normal range, indicating decreased levels of urea nitrogen in the blood, which may suggest a potential health concern, such as malnutrition, liver disease, or overhydration, and requires consultation with a healthcare provider for proper evaluation. This low value may be caused by several conditions, including malnutrition or severe protein deficiency, liver disease, overhydration, or pregnancy, and may also occur with certain medications like anabolic steroids or growth hormone 1. The normal range for BUN is typically 7-20 mg/dL for adults, and low levels can be clinically significant and should not be ignored. BUN is measured because urea is a waste product formed when protein breaks down in the body and is then filtered by the kidneys. While high BUN levels often receive more attention as they can indicate kidney dysfunction, low levels can also indicate other health issues.
Some studies have investigated the effects of certain medications, such as angiotensin-converting enzyme (ACE) inhibitors, on renal function and BUN levels 2, 3. However, these studies are not directly relevant to the interpretation of a low BUN level. A more recent study on preventing acute kidney injury in high-risk patients found that temporarily discontinuing certain medications, such as diuretics, can help prevent complications like acute kidney injury 1. Another study found that ACE inhibitors can have benefits for kidney and cardiovascular outcomes in patients with non-dialysis chronic kidney disease stages 3-5, but may also increase the risk of hyperkalemia and cough 4.
In clinical practice, a low BUN level like 4 mg/dL would prompt a healthcare provider to investigate potential underlying causes, such as malnutrition or liver disease, and to consider dietary changes or further testing as needed. The healthcare provider may also review the patient's medication list to determine if any medications, such as anabolic steroids or growth hormone, could be contributing to the low BUN level. It is essential to consult with a healthcare provider to determine the cause of a low BUN level and to develop an appropriate treatment plan.