Table 2.
Method principles, sample matrix, units and analytical precision of laboratory measurements
| Analyte | Method principle | Sample matrix | Unit | Precision (CV, analytical) |
Time point for collection (visit number)* |
| Ferritin | ECLIA | Serum | µg/L | 7% | 1–11 |
| Iron | Photometry | Serum | µmol/L | 4% | 1–11 |
| Transferrin | Photometry | Serum | 1–11 | ||
| Vitamin B12 | ECLIA | Serum | pmol/L | 12% | 1–11 |
| Folic acid | ECLIA | Serum | nmol/L | 12% | 1–11 |
| C reactive protein | Photometry | Serum | mg/L | 5% | 1–11 |
| Creatinine | Photometry | Serum | µmol/L | 2.5% | 1–11 |
| Sodium | ISE | Serum | mmol/L | 1.0% | 1–11 |
| Potassium | ISE | Serum | mmol/L | 1.2% | 1–11 |
| Calcium | Photometry | Serum | mmol/L | 1.5% | 1–11 |
| Magnesium | Photometry | Serum | mmol/L | 3.0% | 1–11 |
| Phosphate | Photometry | Serum | mmol/L | 2.0% | 1–11 |
| Albumin | Photometry | Serum Urine |
g/L | 3.0% | 1–11 2, 4, 7 and 11 |
| Total protein | Photometry | Serum | g/L | 2.5% | 1–11 |
| Uric acid | Photometry | Serum | µmol/L | 4.0% | 1–11 |
| Glucose | Photometry | Serum/plasma | mmol/L | 2.0% | 1–4, 7 and 11 |
| Alanine aminotransferase | Photometry | Serum | U/L | 5% | 1–11 |
| Aspartate transaminase | Photometry | Serum | U/L | 9.0% | 1–11 |
| Alkaline phosphatase | Photometry | Serum | U/L | 3.0% | 1–11 |
| Gamma-glutamyl transpeptidase | Photometry | Serum | U/L | 3.0% | 1–11 |
| Lactate dehydrogenase | Photometry | Serum | U/L | 5.5% | 1–11 |
| Creatine kinase | Photometry | Serum Urine |
U/L | 5.0% | 1–11 2, 4, 7 and 11 |
| Bilirubin | Photometry | Serum | µmol/L | 5.0% | 1–11 |
| Amylase | Photometry | Serum | 1–11 | ||
| Total cholesterol | Photometry | Serum | mmol/L | 2.5% | 1–11 |
| HDL cholesterol | Photometry | Serum | mmol/L | 3.0% | 1–11 |
| LDL cholesterol | Photometry | Serum | mmol/L | 3.0% | 1–11 |
| Triglycerides | Photometry | Serum | mmol/L | 3.0% | 1–4, 7 and 11 |
| Thyroid-stimulating hormone | ECLIA | Serum | mIE/L | 5.0% | 1–11 |
| Unbound triiodothyronine | ECLIA | Serum | pmol/L | 5.0% | 1–11 |
| Unbound thyroxine | ECLIA | Serum | pmol/L | 5% | 1–11 |
| Parathyroid hormone | ECLIA | Plasma | pmol/L | 6.0% | 1–11 |
| 25-OH-vitamin D | ECLIA | Serum | nmol/L | 6.5% | 1–11 |
| Β-human chorionic gonadotropin† | ECLIA | Serum | IE/L | 5.0% | 1 |
| Paracetamol | Photometry | Serum | µmol/L | 3.0% | 2, 4, 7 and 11 |
| HbA1c | HPLC | Blood | % | 1.4% | 1–11 |
| Complete blood count | Photometry Impedance Flow cytometry |
Blood | g/dL % cells/L |
1.0%–10.0% | 1–11 |
| Thiamin | HPLC | Serum | nmol/L | 4.5% | 2 and 4–11 |
| Bone alkaline phosphatase | CLIA | Serum | U/L | 9.5 U/L 10% 45 U/L 13% |
2 and 4–11 |
| C-telopeptide of type I collagen | ECLIA | Serum | µg/L | 0.12 µg/L 13% 0.32 µg/L 8% |
2 and 4–11 |
| Procollagen type I N-terminal propeptide | ECLIA | Serum | µg/L | 5% | 2 and 4–11 |
| Insulin | ECLIA | Serum | pmol/L | 4% | 2, 4, 7 and 11 |
| C peptide | ECLIA | Serum | pmol/L | 4% | 2, 4, 7 and 11 |
| Anti-GAD | IP | Serum | ai | 0.25 ai 25% 1.45 ai 8% |
1 |
| Anti-IA2 | IP | Serum | ai | 0.32 ai 18% 1.66 ai 12% |
1 |
| Samples for storage | Serum, plasma, blood, urine and faeces | 1–4, 7 and 11 |
*Fasting blood samples visit 2, 4, 7 and 11.
†Women only.
ai, antibody index; CLIA, chemiluminescent immunoassay; CV, coefficient of variation; ECLIA, electro-CLIA; HPLC, high-performance liquid chromatography; IP, immunoprecipitation; ISE, ion selective electrode.