Table 1:
Laboratory results included in the initial work-up and evaluation of a 76-year-old man with pseudo-thrombotic microangiopathy caused by severe vitamin B12 deficiency
| Investigation | Value | Reference range |
|---|---|---|
| Hemoglobin, g/L | 45 | 135–175 |
| MCV, fL | 111 | 80–100 |
| Platelets, × 109/L | 68 | 150–400 |
| Leukocytes, × 109/L | 2.9 | 4–11 |
| Neutrophils, × 109/L | 1.8 | 2–6.3 |
| Peripheral blood film | Few schistocytes, moderate dacrocytes | |
| INR | 1.4 | 0.9–1.2 |
| aPTT, s | 30 | 27–42 |
| Fibrinogen, g/L | 1.5 | 1.9–4.7 |
| Creatinine, μmol/L | 92 | 64–111 |
| Glomerular filtration rate predicted, mL/min | 74 | > 60 |
| Total bilirubin, μmol/L | 72.8 | 3.4–20.5 |
| Unconjugated bilirubin, μmol/L | 58 | 0–12 |
| Conjugated bilirubin, μmol/L | 14.8 | 1.6–8.6 |
| Direct antiglobulin test | Negative | Negative |
| Lactate dehydrogenase, U/L | > 4500 | 110–230 |
| Reticulocyte count, × 109/L | 80 | 10–100 |
| Haptoglobin, g/L | Absent | Present |
| High-sensitivity troponin, ng/L | 10 | < 34 |
| Vitamin B12, pmol/L* | < 117 | 138–652 |
| Antiphospholipid antibody screen* | Negative | |
| d-dimer, ng/mL* | 40 052 | < 500 |
| ANA screen* | Negative | |
| Rheumatoid factor, IU/mL* | 15 | < 10 |
| ADAMTS13*, % | 56 | < 10 indicates severely decreased ADAMTS13 activity |
| Anti-ADAMTS13 antibodies* | Negative | Negative |
| Anti-parietal cell antibodies* | Negative | < 1:80 |
| Anti-intrinsic factor antibodies* | Negative | Negative |
| Flow cytometry for paroxysmal nocturnal hemoglobinuria* | Negative | Negative |
Note: aPTT = activated partial thromboplastin time, ADAMTS13 = a disintegrin and metalloproteinase with thrombospondin motifs 13, ANA = anti-nuclear antibody, INR = international normalized ratio, MCV = mean corpuscular volume.
*
Laboratory tests ordered immediately upon transfer to tertiary care hospital (day 2 of hospital admission).