title: Bone resorption in multiple myeloma and in monoclonal gammopathy of undetermined significance: quantification by urinary pyridinium cross-links of collagen.
abstract: To quantify osseous breakdown in multiple myeloma (MM), monoclonal gammopathy of undetermined significance (MGUS), and benign osteoporosis, we measured urinary levels of pyridinium cross-links of collagen in 50 patients with newly diagnosed and untreated MM, 40 patients with MGUS, 40 untreated patients with osteoporotic vertebral fractures, and 64 healthy adults. Ion-paired, reverse-phase high-performance liquid chromatography (HPLC) was used to measure total urinary excretion of pyridinoline (h-PYD) and deoxypyridinoline (h-DPD). Urinary excretion of free immunoreactive deoxypyridinoline (i-DPD) was determined with an enzyme immunoassay. MM patients had significantly (P < .0001) higher levels of h-PYD, h-DPD, and i-DPD than the healthy adults, patients with MGUS, or patients with osteoporosis. The MGUS and osteoporosis groups presented with elevated (P < .05) levels of urinary pyridinium cross-links when compared with healthy controls. In 20 MM patients who subsequently received chemotherapy, the percent changes in i-DPD did not correlate with the changes in the monoclonal protein. In one of three patients experiencing a transition of initial MGUS into stage I MM, i-DPD increased above the upper limit of the normal range. In 13 patients with stable MGUS, i-DPD remained normal in repeated measurements. Based on the upper limits of the normal range, the sensitivity of urinary pyridinium cross-links in stage I and II MM was low (<50%), but it was between 78% (h-DPD) and 93% (i-DPD) in stage III MM. Specificity in patients with MGUS was between 87% (h-PYD) and 97% (h-DPD). In conclusion, determining the urinary excretion of pyridinium cross-links seems to be a promising noninvasive and thus easily repeatable method for evaluating the actual degree of osseous breakdown. Although measurement of pyridinium cross-link levels is not useful in discriminating patients with MGUS from early-stage myeloma patients, determination of i-DPD levels may contribute importantly to clinical guidance, since increased i-DPD levels seem to identify patients who are particularly likely to benefit from osteoclast-inhibiting drugs such as bisphosphonates. The fact that in a number of patients paraprotein concentrations and i-DPD levels did not change in parallel but instead diverged strongly after chemotherapy might explain the observation that bone lesions sometimes progress even in patients who achieve complete remission.
authors.affiliation: First Department of Medicine and Medical Oncology, Wilhelminenspital, Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Pecherstorfer
authors.forename: M J
authors.initials: MJ
authors.lastname: Seibel
authors.forename: H W
authors.initials: HW
authors.lastname: Woitge
authors.forename: E
authors.initials: E
authors.lastname: Horn
authors.forename: J
authors.initials: J
authors.lastname: Schuster
authors.forename: J
authors.initials: J
authors.lastname: Neuda
authors.forename: P
authors.initials: P
authors.lastname: Sagaster
authors.forename: H
authors.initials: H
authors.lastname: Köhn
authors.forename: P
authors.initials: P
authors.lastname: Bayer
authors.forename: D
authors.initials: D
authors.lastname: Thiébaud
authors.forename: H
authors.initials: H
authors.lastname: Ludwig
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D001862:Bone Resorption / Q000652:urine*; D003094:Collagen / Q000652:urine*; D003432:Cross-Linking Reagents; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000503:physiopathology* / Q000652:urine; D010265:Paraproteinemias / Q000503:physiopathology* / Q000652:urine; D011726:Pyridinium Compounds / Q000652:urine*
chemical_list: D015415:Biomarkers; D003432:Cross-Linking Reagents; D011726:Pyridinium Compounds; D003094:Collagen