| MCR | Medical Corps Reserve; melanocortin receptor; message competition ratio; metabolic clearance rate; m... |
|---|---|
| MDTR | mean diameter-thickness ratio |
| M/E | myeloid/erythroid [ratio] |
| MER | mean ejection rate; medical emergency room; methanol extraction residue; murmur/energy ratio |
| M/F | male/female [ratio] |