Should you have nothing by mouth before a BMP blood test?

Yes, it is generally recommended to fast before a BMP (basic metabolic panel) blood test. This means avoiding food and drink for a certain period of time, typically 8 to 12 hours, before the blood draw.

The reason for fasting is that certain foods and beverages can affect the levels of various substances in your blood, potentially interfering with the accuracy of the test results. For example, eating a meal high in protein can temporarily increase the levels of certain amino acids in your blood, which can affect the interpretation of the test results.

In addition to food, you should also avoid drinking alcohol, smoking, and exercising vigorously before a BMP test. These activities can also affect the test results.

However, it's important to note that the specific fasting requirements may vary depending on the laboratory performing the blood test. Some laboratories may have different guidelines, so it's always best to follow the instructions provided by your healthcare provider or the laboratory.