Serum surfactant proteins‐A (SP‐A) and ‐D (SP‐D) levels in healthy volunteers according to site study
| Denver | Iowa | Japan | |
| SP‐A ng·mL−1 | |||
| n | 46 | 49 | 246 |
| Median | 39.60 | 22.20 | 21.20 |
| 75th percentile | 49.40 | 31.55 | 29.00 |
| 25th percentile | 24.28 | 10.10 | 18.00 |
| SP‐D ng·mL−1 | |||
| n | 46 | 49 | 131 |
| Median | 97.25 | 86.98 | 42.67 |
| 75th percentile | 127.86 | 125.33 | 60.67 |
| 25th percentile | 71.31 | 61.67 | 33.36 |