| pH | Urine | Chemistry - non-challenge | LP383455-5 | 2 |
| pH | Urine | Urinalysis | LP402533-6 | 2 |
| Phenylpropionylglycine | LP14517-4 | 2 |
| Phenylpropionylglycine | Urine | Chemistry - non-challenge | LP383965-3 | 2 |
| Phenylpyruvate | LP15794-8 | 2 |
| Phenytoin | LP14732-9 | 2 |
| Phosphate | Hair | Chemistry - non-challenge | LP386052-7 | 2 |
| Phosphate crystals amorphous | LP18117-9 | 2 |
| Phosphate crystals amorphous | Urine sediment | Urinalysis | LP402408-1 | 2 |
| Phosphatidylglycerol | LP15798-9 | 2 |
| Phosphatidylglycerol | Amniotic fluid | Chemistry - non-challenge | LP382373-1 | 2 |
| Pipecolate | LP15808-6 | 2 |
| Plasma cell precursor | LP31552-0 | 2 |
| Plasma cell precursor | Blood | Hematology and Cell counts | LP393193-0 | 2 |
| Plasma cells | Blood | Hematology and Cell counts | LP393190-6 | 2 |
| Plasma cells | Body fluid | Hematology and Cell counts | LP393191-4 | 2 |
| Plasma cells | Bone marrow | Hematology and Cell counts | LP393192-2 | 2 |
| Plasma cells immature | LP15079-4 | 2 |
| Plasma cells immature | Bone marrow | Hematology and Cell counts | LP393199-7 | 2 |
| Plasma cells with abnormal marker pattern | LP281527-4 | 2 |
| Plasma cells with abnormal marker pattern | Bone marrow | Hematology and Cell counts | LP407475-5 | 2 |
| Platelet distribution width | LP29639-9 | 2 |
| Platelet distribution width | Blood | Hematology and Cell counts | LP393240-9 | 2 |
| Platelet factor | LP30937-4 | 2 |
| Platelet factor 4 | LP16902-6 | 2 |
| Platelet factor 4 | Platelet poor plasma | Coagulation | LP394309-1 | 2 |
| Platelet indices | LP31668-4 | 2 |
| Platelet-induced clot retraction | LP449128-0 | 2 |
| Platelet-induced clot retraction | Blood | Coagulation | LP450584-0 | 2 |
| Platelets Large | LP29640-7 | 2 |
| Platelets Large | Blood | Hematology and Cell counts | LP393231-8 | 2 |
| Polymorphonuclear cells | LP17840-7 | 2 |
| Polymorphonuclear cells | Blood | Hematology and Cell counts | LP393160-9 | 2 |
| Porphobilinogen | Urine | Chemistry - non-challenge | LP386503-9 | 2 |
| Porphyrins | Serum or Plasma | Chemistry - non-challenge | LP386409-9 | 2 |
| Potassium | Blood | Chemistry - non-challenge | LP386601-1 | 2 |
| Potassium | Red Blood Cells | Chemistry - non-challenge | LP386616-9 | 2 |
| Potassium | Urine | Chemistry - non-challenge | LP386624-3 | 2 |
| Prealbumin | Cerebral spinal fluid | Chemistry - non-challenge | LP384495-0 | 2 |
| Pregnancy associated plasma protein A | LP28774-5 | 2 |
| Pregnancy associated plasma protein A | Serum or Plasma | Chemistry - non-challenge | LP384930-6 | 2 |
| Pristanate (C15:0(CH3)4) | LP18151-8 | 2 |
| Pristanate (C15:0(CH3)4) | Serum or Plasma | Chemistry - non-challenge | LP382196-6 | 2 |
| Procainamide | LP16261-7 | 2 |
| Progesterone | LP14041-5 | 2 |
| Progesterone | Serum or Plasma | Chemistry - non-challenge | LP381487-0 | 2 |
| Prolactin monomeric | LP68274-7 | 2 |
| Prolactin monomeric | Serum or Plasma | Chemistry - non-challenge | LP381391-4 | 2 |
| Prolactin.dimeric | LP200141-2 | 2 |
| Prolactin.dimeric | Serum or Plasma | Chemistry - non-challenge | LP381389-8 | 2 |
| Proline | DBS | Chemistry - non-challenge | LP384269-9 | 2 |
| Prolymphocytes | Blood | Hematology and Cell counts | LP392935-5 | 2 |
| Prolymphocytes | Body fluid | Hematology and Cell counts | LP392936-3 | 2 |
| Promonocytes | Blood | Hematology and Cell counts | LP393040-3 | 2 |
| Promonocytes | Body fluid | Hematology and Cell counts | LP393041-1 | 2 |
| Promyelocytes | Blood | Hematology and Cell counts | LP392856-3 | 2 |
| Promyelocytes | Body fluid | Hematology and Cell counts | LP392857-1 | 2 |
| Promyelocytes | Cerebral spinal fluid | Hematology and Cell counts | LP392858-9 | 2 |
| Protein Fractions | Urine | Chemistry - non-challenge | LP384938-9 | 2 |
| Protein fractions.oligoclonal bands | Cerebral spinal fluid | Chemistry - non-challenge | LP384941-3 | 2 |
| Protein fractions.oligoclonal bands | Serum or Plasma | Chemistry - non-challenge | LP384942-1 | 2 |
| Protein.monoclonal isotype | Urine | Chemistry - non-challenge | LP435281-3 | 2 |
| Proteinase 3 | LP17259-0 | 2 |
| Proteinase 3 | Serum | Serology - non-micro | LP403892-5 | 2 |
| Protoporphyrin | Red Blood Cells | Chemistry - non-challenge | LP386507-0 | 2 |
| Protoporphyrin Free | LP21411-1 | 2 |
| Protoporphyrin Free | Red Blood Cells | Chemistry - non-challenge | LP386512-0 | 2 |
| Pseudocasts | LP31539-7 | 2 |
| Pseudocasts | Urine sediment | Urinalysis | LP402449-5 | 2 |
| Pseudouridine | LP199589-5 | 2 |
| Pyridoxal | Serum or Plasma | Chemistry - non-challenge | LP385162-5 | 2 |
| Pyridoxal phosphate | Serum or Plasma | Chemistry - non-challenge | LP385165-8 | 2 |
| Pyridoxine | Serum or Plasma | Chemistry - non-challenge | LP385168-2 | 2 |
| R-beta aminoisobutyrate | LP201654-3 | 2 |
| RBC casts | Urine sediment | Urinalysis | LP402451-1 | 2 |
| Reducing substances | Stool | Chemistry - non-challenge | LP385610-3 | 2 |
| Reducing substances | Urine | Urinalysis | LP402536-9 | 2 |
| Reduction in clot strength | LP449134-8 | 2 |
| Reduction in clot strength | Blood | Coagulation | LP450583-2 | 2 |
| Renin | LP15273-3 | 2 |
| Renin | Plasma | Chemistry - non-challenge | LP383227-8 | 2 |
| Respiratory syncytial virus | LP14244-5 | 2 |
| Respiratory syncytial virus | XXX | Microbiology | LP378922-1 | 2 |
| Reticulocytes.mature | LP31816-9 | 2 |
| Reticulocytes.mature | Blood | Hematology and Cell counts | LP392548-6 | 2 |
| Reticulocytes.mid | LP31817-7 | 2 |
| Reticulocytes.mid | Blood | Hematology and Cell counts | LP392551-0 | 2 |
| Riboflavin | LP15853-2 | 2 |
| S-adenosylhomocysteine | LP200579-3 | 2 |
| S-adenosylmethionine | LP199517-6 | 2 |
| S-beta aminoisobutyrate | LP201653-5 | 2 |
| Saccharopine | LP201690-7 | 2 |
| SaO2 | Blood arterial | Chemistry - non-challenge | LP383400-1 | 2 |
| Segmented neutrophils | Blood | Hematology and Cell counts | LP392658-3 | 2 |
| Segmented neutrophils | Body fluid | Hematology and Cell counts | LP392659-1 | 2 |
| Segmented neutrophils | Cerebral spinal fluid | Hematology and Cell counts | LP392660-9 | 2 |
| Segmented neutrophils | Peritoneal fluid | Hematology and Cell counts | LP392661-7 | 2 |
| Segmented neutrophils | Pleural fluid | Hematology and Cell counts | LP392662-5 | 2 |
| Segmented neutrophils | Synovial fluid | Hematology and Cell counts | LP392663-3 | 2 |
| Siderocytes | LP65026-4 | 2 |