| Lysine | Cerebral spinal fluid | Chemistry - non-challenge | LP384122-0 | 1 |
| Lysine | DBS | Chemistry - non-challenge | LP384120-4 | 1 |
| Lysine | Serum or Plasma | Chemistry - non-challenge | LP384124-6 | 1 |
| Lyso-sphingomyelin | Blood | Chemistry - non-challenge | LP407451-6 | 1 |
| Lyso-sphingomyelin | DBS | Chemistry - non-challenge | LP407452-4 | 1 |
| Lyso-sphingomyelin | Serum or Plasma | Chemistry - non-challenge | LP407453-2 | 1 |
| Lysophosphatidylcholine(20:0) | LP269795-3 | 1 |
| Lysophosphatidylcholine(20:0) | DBS | Chemistry - non-challenge | LP382363-2 | 1 |
| Lysophosphatidylcholine(22:0) | LP269794-6 | 1 |
| Lysophosphatidylcholine(22:0) | DBS | Chemistry - non-challenge | LP382364-0 | 1 |
| Lysophosphatidylcholine(24:0) | LP269796-1 | 1 |
| Lysophosphatidylcholine(24:0) | DBS | Chemistry - non-challenge | LP382365-7 | 1 |
| Lysosomal enzymes | LP32886-1 | 1 |
| Lysosomal storage disorders | DBS | Chemistry - non-challenge | LP421929-3 | 1 |
| Lysosomal storage disorders suspected | LP111175-8 | 1 |
| Lysosomal storage disorders suspected | DBS | Chemistry - non-challenge | LP433365-6 | 1 |
| Lysozyme | LP14684-2 | 1 |
| Lysozyme | Body fluid | Chemistry - non-challenge | LP383132-0 | 1 |
| Macrocytes | Blood | Hematology and Cell counts | LP393434-8 | 1 |
| Macrophage inflammatory protein 1 alpha | LP421050-8 | 1 |
| Macrophage inflammatory protein 1 alpha | Serum or Plasma | Chemistry - non-challenge | LP427530-3 | 1 |
| Magnesium | Calculus (stone) | Chemistry - non-challenge | LP386019-6 | 1 |
| Magnesium | Stool | Chemistry - non-challenge | LP386029-5 | 1 |
| Malate | LP18441-3 | 1 |
| Malate | Serum or Plasma | Chemistry - non-challenge | LP385335-7 | 1 |
| Maltose | LP97868-1 | 1 |
| Maltose | Urine | Chemistry - non-challenge | LP385593-1 | 1 |
| Mannose-6-phosphate isomerase | LP186037-0 | 1 |
| Mannose-6-phosphate isomerase | White blood cells | Chemistry - non-challenge | LP383142-9 | 1 |
| Maple syrup urine disease | LP56746-8 | 1 |
| Maple syrup urine disease | DBS | Chemistry - non-challenge | LP385847-1 | 1 |
| Mead acid (C20:3w9) | Red Blood Cells | Chemistry - non-challenge | LP382163-6 | 1 |
| Mead acid (C20:3w9) | Serum or Plasma | Chemistry - non-challenge | LP382164-4 | 1 |
| Measles virus | LP16722-8 | 1 |
| Measles virus | XXX | Microbiology | LP378637-5 | 1 |
| Meat fibers | LP15723-7 | 1 |
| Meat fibers | Stool | Chemistry - non-challenge | LP386754-8 | 1 |
| Meconium | LP19409-9 | 1 |
| Meconium | Amniotic fluid | Chemistry - non-challenge | LP386756-3 | 1 |
| Megakaryocytes | LP15074-5 | 1 |
| Megakaryocytes | Bone marrow | Hematology and Cell counts | LP393250-8 | 1 |
| Meperidine | LP16184-1 | 1 |
| Meperidine | Urine | Drug toxicology | LP389968-1 | 1 |
| Mercury | LP14344-3 | 1 |
| Mercury | Blood | Drug toxicology | LP388350-3 | 1 |
| Mesothelial cells | Pericardial fluid | Hematology and Cell counts | LP393510-5 | 1 |
| Metanephrine | Serum or Plasma | Chemistry - non-challenge | LP381249-4 | 1 |
| Metanephrine and Normetanephrine | Serum or Plasma | Chemistry - non-challenge | LP416959-7 | 1 |
| Metanephrine and Normetanephrine | Urine | Chemistry - non-challenge | LP416960-5 | 1 |
| Metanephrine Free | LP31520-7 | 1 |
| Metanephrine Free | Serum or Plasma | Chemistry - non-challenge | LP381251-0 | 1 |
| Methanol | LP14349-2 | 1 |
| Methanol | Serum or Plasma | Drug toxicology | LP391443-1 | 1 |
| Methaqualone | LP15016-6 | 1 |
| Methaqualone | Urine | Drug toxicology | LP389787-5 | 1 |
| Methemoglobin | Blood | Chemistry - non-challenge | LP383409-2 | 1 |
| Methemoglobin | Cerebral spinal fluid | Chemistry - non-challenge | LP383410-0 | 1 |
| Methicillin resistant Staphylococcus aureus | LP34425-6 | 1 |
| Methicillin resistant Staphylococcus aureus | LP18334-0 | 1 |
| Methicillin resistant Staphylococcus aureus | XXX | Microbiology | LP416930-8 | 1 |
| Methionine | Amniotic fluid | Chemistry - non-challenge | LP384143-6 | 1 |
| Methionine | Cerebral spinal fluid | Chemistry - non-challenge | LP384147-7 | 1 |
| Methionine | Serum or Plasma | Chemistry - non-challenge | LP384149-3 | 1 |
| Methotrexate | LP16198-1 | 1 |
| Methotrexate | Serum or Plasma | Drug toxicology | LP390957-1 | 1 |
| Methylglutarylcarnitine (C6-DC) | LP69348-8 | 1 |
| Methylglutarylcarnitine (C6-DC) | DBS | Chemistry - non-challenge | LP381711-3 | 1 |
| Methylmalonate | DBS | Chemistry - non-challenge | LP385115-3 | 1 |
| Methylmalonate | Serum or Plasma | Chemistry - non-challenge | LP385117-9 | 1 |
| Methylmalonate | Urine | Chemistry - non-challenge | LP385118-7 | 1 |
| Methylmalonylcarnitine (C4-DC) | Serum or Plasma | Chemistry - non-challenge | LP381642-0 | 1 |
| Methylmalonylcarnitine (C4-DC)+3-Hydroxyisovalerylcarnitine (C5-OH) | LP133650-4 | 1 |
| Methylmalonylcarnitine (C4-DC)+3-Hydroxyisovalerylcarnitine (C5-OH) | DBS | Chemistry - non-challenge | LP381646-1 | 1 |
| Methylsuccinate | DBS | Chemistry - non-challenge | LP383949-7 | 1 |
| Methylsuccinate | Serum or Plasma | Chemistry - non-challenge | LP383950-5 | 1 |
| Microcytes | LP17463-8 | 1 |
| Microcytes | Blood | Hematology and Cell counts | LP393436-3 | 1 |
| Microorganisms seen | LP99299-7 | 1 |
| Microorganisms seen | Urine sediment | Urinalysis | LP402505-4 | 1 |
| Microsporidia | LP14825-1 | 1 |
| Microsporidia | Stool | Microbiology | LP444606-0 | 1 |
| Misc toxins | LP30608-1 | 1 |
| Miscellaneous toxic small organic and inorganic molecules | LP31433-3 | 1 |
| Mitochondria Genes | LP33178-2 | 1 |
| Monoclonal band observed | Serum or Plasma | Chemistry - non-challenge | LP384583-3 | 1 |
| Monoclonal band observed | Urine | Chemistry - non-challenge | LP384584-1 | 1 |
| Monocytes | Pericardial fluid | Hematology and Cell counts | LP393032-0 | 1 |
| Monomethylarsonate | LP417702-0 | 1 |
| Monomethylarsonate | Urine | Drug toxicology | LP419097-3 | 1 |
| Mononuclear cells | Dialysis fluid peritoneal | Hematology and Cell counts | LP393134-4 | 1 |
| Mononuclear cells | Pericardial fluid | Hematology and Cell counts | LP393135-1 | 1 |
| Monounsaturated fatty acids | Serum or Plasma | Chemistry - non-challenge | LP382082-8 | 1 |
| MTHFR gene | LP19739-9 | 1 |
| MTHFR gene c.677C>T | LP21193-5 | 1 |
| MTHFR gene c.677C>T | Blood or Tissue | Mutations | LP409968-7 | 1 |
| Mucopolysaccharidosis type I | LP203226-8 | 1 |
| Mucopolysaccharidosis type I | DBS | Chemistry - non-challenge | LP421934-3 | 1 |
| Mucopolysaccharidosis type II newborn screen interpretation | LP437993-1 | 1 |
| Mucopolysaccharidosis type II newborn screen interpretation | DBS | Chemistry - non-challenge | LP440630-4 | 1 |
| Mullerian inhibiting substance | LP34629-3 | 1 |