The protoporphyrin test is used to diagnose blood problems caused by lead. The test can show lead exposure or lead poisoning.

This test measures levels of protein S, a protein in the blood that helps it to clot.

Protein electrophoresis is a test that measures specific proteins in the blood.

This test measures the level of protein C in your blood. If you have too little protein C, called a protein C deficiency, it means that your blood may clot too much.

This test measures the level of prolactin in your blood. The test can help find out if you have a pituitary gland tumor.

This blood test measures proinsulin, a building block for insulin. Measuring proinsulin in your blood can help figure out your risk for type 1 or type 2 diabetes.

This test measures the level of a hormone called progesterone in your blood. You may need this test if you are having trouble getting pregnant.

The prealbumin screen is a blood test to see whether you are getting enough protein in your diet.

This test measures the amount of potassium in your blood. It's often part of a routine blood test to check your level of electrolytes.

This test looks for substances called porphyrins in your urine. If high levels are present, you may have a disease that affects the way the hemoglobin in your blood works.