Table 1.
Demographics and plasma amino acid levels in controls vs. adult and pediatric COVID-19 patients
| Clinical characteristics | Controls (n = 28) | Adult COVID-19 (n = 32) | P value | Pediatric COVID-19/MIS-C (n = 20) | P value |
| Patient demographics | |||||
| Mean age ± SD (range in years) | (41−50)*** | 60 ± 17 (20−99) | — | 11 ± 5 (3−20) | — |
| Female, n (%) | 20 (71.4) | 11 (34.3) | — | 10 (50.0) | — |
| Comorbidity present, n (%) | 4 (14.3) | 17 (53.1) | — | 5 (25.0) | — |
| Multisystem inflammatory syndrome in children, n (%) | — | — | — | 9 (45.0) | — |
| Infiltrate on chest X-ray, n (%) | — | 28 (87.5) | — | 15 (75.0) | — |
| Supplemental oxygen, n (%) | — | 19 (59.4) | — | 14 (70.0) | — |
| Ventilator use, n (%) | — | 7 (21.9) | — | 3 (15.0) | — |
| Intensive care unit, n (%) | — | 9 (28.1) | — | 16 (80.0) | — |
| Total days in hospital, median (IQR) | — | 18.25 (14−31) | — | 9 (8−22) | — |
| Death, n (%) | — | 3 (9.4) | — | 2 (10.0) | — |
| — | — | ||||
| — | — | ||||
| Amino acids (μM) | |||||
| Arginine pathway-related amino acids and ratios | |||||
| Arginine | 92.9 (29.2) | 58.2 (50.8) | 0.002 | 52.0 (52.3) | 0.001 |
| Ornithine | 98.5 (30.1) | 110.0 (51.3) | 0.30 | 110.7 (65.7) | 0.39 |
| Citrulline | 18.4 (4.1) | 12.8 (6.9) | <0.001 | 6.9 (5.1) | <0.001 |
| Glutamate | 211.4 (63.7) | 213.9 (132.4) | 0.93 | 165.1 (123.3) | 0.09 |
| Glutamine | 1,023.0 (163.7) | 614.5 (282.2) | <0.001 | 910.6 (293.5) | 0.10 |
| Arginine-to-ornithine ratio | 1.01 (0.40) | 0.55 (0.46) | <0.001 | 0.52 (0.45) | <0.001 |
| Global arginine bioavailability ratio | 0.84 (0.31) | 0.48 (0.38) | <0.001 | 0.49 (0.43) | 0.002 |
| Glutamine-to-glutamate ratio | 5.41 (2.24) | 4.69 (3.73) | 0.38 | 8.62 (5.92) | 0.01 |
| Other amino acids | |||||
| Alanine | 504.7 (98.0) | 328.9 (114.6) | <0.001 | 331.0 (119.1) | <0.001 |
| Cysteine | 4.3 (1.5) | 4.0 (1.4) | 0.41 | 4.1 (2.0) | 0.73 |
| Cystine | 7.0 (3.5) | 7.2 (5.7) | 0.87 | 11.7 (6.6) | 0.003 |
| Glycine | 6,884.0 (2,197) | 4,286.2 (1,195) | <0.001 | 5,806.1 (1,505) | 0.06 |
| Histidine | 76.2 (14.3) | 39.3 (23.5) | <0.001 | 52.9 (27.0) | <0.001 |
| Isoleucine | 20.2 (5.4) | 18.7 (7.4) | 0.38 | 16.0 (8.4) | 0.04 |
| Leucine | 106.8 (39.2) | 102.1 (63.8) | 0.74 | 77.3 (65.5) | 0.06 |
| Lysine | 231.2 (37.5) | 219.0 (68.3) | 0.41 | 202.5 (99.4) | 0.17 |
| Methionine | 25.4 (7.0) | 21.2 (7.9) | 0.03 | 21.9 (12.6) | 0.23 |
| Phenylalanine | 40.8 (7.1) | 57.7 (42.7) | 0.04 | 55.4 (23.4) | 0.003 |
| Proline | 246.4 (63.4) | 176.3 (65.3) | <0.001 | 175.2 (79.4) | 0.001 |
| Serine | 267.1 (58.5) | 212.7 (74.6) | 0.003 | 298.0 (111.8) | 0.22 |
| Threonine | 40.6 (11.3) | 34.7 (13.5) | 0.07 | 42.0 (25.1) | 0.80 |
| Tryptophan | 40.8 (7.3) | 21.6 (7.0) | <0.001 | 20.5 (10.7) | <0.001 |
| Tyrosine | 46.2 (10.1) | 65.4 (38.1) | 0.01 | 32.7 (11.7) | <0.001 |
| Valine | 190.7 (41.2) | 214.6 (82.5) | 0.17 | 167.2 (66.3) | 0.14 |
***
Only mean age range in decades available.