| INP | idiopathic neutropenia |
|---|---|
| INS | idiopathic nephrotic syndrome; insulin; insurance |
| IOH | idiopathic orthostatic hypotension |
| IPF | idiopathic pulmonary fibrosis; infection-potentiating factor; interstitial pulmonary fibrosis |
| IRDS | idiopathic respiratory distress syndrome; infant respiratory distress syndrome |