Once taken the blood is sent to a lab for testing, results are usually back within a few days. If your T-levels are 300ng.dl or above, then your testosterone production is considered to be normal. Below that reading, you need to try and increase your hormone levels as you are technically suffering with low T. A B-type natriuretic peptide (BNP) test is a blood test. It measures the levels of a certain type of hormone in your blood called a B-type natriuretic peptide. This test gives your healthcare provider information about your heart. Higher-than-normal levels of BNP in your blood can be a sign that your heart isn’t working as it should. 3 min read. It’s a simple blood test that lets your doctor measure how much ammonia is in your blood. Bacteria in your gut and in your cells create ammonia when your body breaks down protein hI7S.