| Na[+] | 
| NAAT (nucleic acid amplification test), chlamydia | 
| Naegleriasis | 
|  | 
|  | 
| Nasal continuous positive airway pressure (nCPAP) titration | 
|  | 
|  | 
|  | 
|  | 
|  | 
| nBiPAP | 
| nCPAP | 
| Neck CT scan | 
| Neck ultrasound | 
|  | 
|  | 
|  | 
|  | 
|  | 
|  | 
|  | 
| Neonatal screen for hypothyroidism | 
| Neonatal thyroid-stimulating hormone (TSH) | 
| Neonatal thyroxine (T4) | 
|  | 
| Nephritis, acute interstitial | 
| Nephroblastoma | 
|  | 
|  |