Table 1.
Comparison of commercially available human sclerostin assays*.
| Assay Metric | DiaSorin | BioMedica | TECO | R&D | MesoScale [23, 24] | |
|---|---|---|---|---|---|---|
|
| ||||||
| Range | 50 to 6500 pg/mL | 170 to 5455pg/mL | 58 to 3000 pg/mL | 31.3 to 2000 pg/mL | 1 to 10,000 pg/mL | |
|
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| Reference Range | Serum | 124 to 853 pg/mL | 248 to 652 pg/mL | 67.0 to 300 pg/mL | 12.4 to 68.19 pg/mL | |
| EDTA Plasma | 148 to 955 pg/mL | 386 to 857 pg/mL | 249 to 1153 pg/mL | 200 to 712 pg/mL | ||
| Heparin Plasma | 222 to 805 pg/mL | |||||
|
| ||||||
| Precision | Intra | <2.5% | <7% | <4.2% | <2.1% | <6% |
| Inter | <5% | <10% | <4.8% | <10.8% | <10% | |
|
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| LOQ | ≤ 50 pg/mL | 170 pg/mL | 58 pg/mL | ND | ND | |
| LOD | ≤ 20 pg/mL | 73 pg/mL | 9 pg/mL | 3.8 pg/mL | 1pg/mL | |
| LOB | ≤ 4 pg/mL | 5.9 pg/mL | 8 pg/mL | 1.74 pg/mL MDD | ND | |
|
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| Linearity | 100.3% across entire range | 110% mean @ 1:1, 1:3, 1:7 | 100.3% across entire range | 102% | ||
|
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| Recovery | 94% | 94% | 98% | 86 to 112% | ||
|
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| TTFR | 65 minutes | 18 hours | 4.5 hours | 4.5 hours | 4.5 hours | |
|
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| Sample Volume | 50 μL | 20 μL | 25 μL | 50 μL | 25 μL | |
|
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| Sample Type | Serum EDTA Plasma |
Serum EDTA/heparin Plasma |
Serum EDTA/heparin Plasma |
Serum EDTA/heparin Plasma Cell culture supernatants |
Serum EDTA Plasma |
|
|
| ||||||
| Sample Equivalence | EDTA Plasma = 0.94 × (fresh serum) + 57.69 Fresh SST = 1.00 × (fresh serum) − 19.63 |
Serum = 0.8438 × (heparin plasma): R=0.9815 Serum = 0.8509 × (EDTA plasma): R=0.9755 |
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|
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| Specificity | <0.1% reactivity Noggin, SOSTDC1, BMPs 2,4,5,6,7,8a | No reactivity to Noggin or SOSTDC1 | <0.1% cross reactivity Cerbeus, DAN, Gremlin, LRP4,5,6, BMP 2,4,5,6,7 BMPRIA |
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|
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| Fragments Detected | NO | YES | INFERRED [10] | No detection reported£ | ||
|
| ||||||
| Interference | ||||||
| Bilirubin. | 15 mg/dL | 40mg/dL | ||||
| Hemoglobin. | 300 mg/dL | 500 mg/dL | ||||
| Triglycerides. | 3000 mg/dL | 3000 mg/dL | ||||
| Glucose. | 300 mg/dL | 1200 mg/dL | ||||
| Cholesterol. | 302 mg/dL | 500 mg/dL | ||||
| Albumin. | 12000mg/dL | 6000mg/dL | ||||
| Gamma globulin. | 12000 mg/dL | 6000 mg/dL | ||||
Values tabulated for the BioMedica, TECO, R&D and MesoScale assays come from the respective manufacturer’s IFUs.
Reported specificity [23] of capture (2 epitopes: one to the N-terminus [aa1 to aa50] and another to the distal C-terminus [aa150 to aa191]) and tracer (3 epitopes: to the N-terminus, to the third loop [Cys111 to Lys143] and to the C-terminus) antibodies for the MesoScale assay are inconsistent with the assay’s reported lack of detection of sclerostin fragments. Although one would expect the reported lack of detection against the three fragments cited [23] comprising {1. a Loop1-2-3 fragment without N- and C- termini ( ie aa51 to aa149), 2. Loop 1 [Cys57 to Cys82] and Loop 3 [Cys111 to Lys143] without N- and C- termini, respectively, and 3. Loop 2 [Cys86 to Arg110]}, one would expect more realistic natural fragments, like those derived from endogenous thrombin action, to be detected, since the capture Ab of the MesoScale assay has both N- and C-terminal reactivity.