On a lab report, NP most commonly stands for “Not Performed,” meaning the test was ordered but the laboratory did not run it. You’ll typically see this next to a specific test name where you’d normally expect a number or result. Less commonly, NP can refer to natriuretic peptide, a cardiac biomarker, or it may appear near a provider’s name to indicate a Nurse Practitioner ordered the test.
NP as “Not Performed”
When NP appears in the results column of your lab report, it almost always means the lab received your sample but couldn’t complete that particular test. This is different from a negative result, which labs abbreviate as “neg” or “negative.” An NP result gives you no information about what the test would have shown. It simply means the analysis never happened.
Several things can prevent a lab from running a test. The most common is an insufficient sample: not enough blood, urine, or tissue was collected to perform every test that was ordered. Blood samples that have hemolyzed (where red blood cells break open and release their contents) are rejected for many tests, especially potassium, magnesium, iron, bilirubin, and coagulation panels. A clotted specimen, a mislabeled tube, or a sample that sat too long before processing can also force the lab to mark a test as not performed.
If you see NP on your report, it typically means your provider will need to decide whether to reorder that test, which may require another blood draw or sample collection. Your provider’s office is usually notified when a test isn’t completed, but if you notice it on a patient portal before anyone contacts you, calling the office to ask about next steps is reasonable.
NP as a Natriuretic Peptide Test
In some contexts, NP is shorthand for natriuretic peptide, a protein your heart releases when it’s working harder than normal to pump blood. You’re more likely to see this written out as BNP (brain natriuretic peptide) or NT-proBNP (the inactive fragment produced alongside BNP) rather than simply “NP.” But medical literature and some lab systems do use NP as the umbrella abbreviation for both forms.
These tests help evaluate heart failure. Your heart produces more natriuretic peptide when its walls are stretched and under strain, so higher levels in the blood suggest the heart is struggling. BNP and NT-proBNP testing is highly sensitive for diagnosing or ruling out heart failure, and the levels correlate with how severe the condition is. If your lab report shows a BNP or NT-proBNP result with a number next to it, that’s a measurement of this heart stress marker, not a “not performed” flag.
NP as Nurse Practitioner
You may also spot “NP” on your lab report near the ordering provider’s name. In this case, it’s a credential: Nurse Practitioner. It identifies who requested the test, not anything about the result itself. This designation typically appears in the header or footer of the report alongside the provider’s name and has no bearing on how the test was processed or what the results mean.
How to Tell Which Meaning Applies
Context on the report makes the distinction clear. If NP sits in the result field where you’d expect a number or “normal/abnormal,” it means the test was not performed. If it appears as part of a test name (like “BNP” or “NT-proBNP”), it’s referring to the natriuretic peptide cardiac marker. And if it follows a person’s name at the top of the report, it’s a provider credential.
Lab reports vary widely between health systems, and abbreviations aren’t always standardized. Most labs include a reference guide or legend somewhere on the report, often on the last page, that defines the abbreviations they use. If your patient portal or printed report doesn’t include one, your provider’s office or the lab itself can clarify what a specific notation means on your particular report.