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.

This test looks for P. jirovecii fungus in your lung tissue or in fluid from a lung. This fungus causes pneumocystis pneumonia.

This test measures the number of platelet cells in your blood. It can give your doctor valuable information about how well your blood clots stop bleeding, how well your bone marrow is working, and diseases that affect your platelet count.

This test looks for platelet antibodies in your blood to find out the cause of a low platelet count.