Biochemical bone markers in patients with multiple myeloma

Enhanced bone resorption is a characteristic finding in multiple myeloma (MM). The aim of this study was to assess the newer biochemical bone markers in patients with myeloma, We studied 17 MM patients - 10 males (3 untreated, 5 in remission, 2 responding), 7 females (3 in remission, 4 responding) and 15 normal controls. Serum bone specific alkaline phosphatase (BSALP), osteocalcin (OC) and procollagen type 1 C-terminal peptide (PICP) were determined as markers of bone formation, while serum tartrate resistant acid phosphatase (TRAP), urinary deoxypyridinoline (Dpyr) and calcium (Ca) were determined as markers of bone resorption and the ratio of the levels of bone formation/resorption were determined. All markers were measured by enzyme immunoassays (Metra Biosystems), except for TRAP by an in-house enzymatic assay and Ca by the cresolphthalein method. The Dpyr and Ca were expressed as a ratio to urinary creatinine (Cr) excretion. There were significantly higher (i) (Dpyr/Cr)PICP ratio in male MM patients than in controls (P < 0.05); (ii) (a) urinary Dpyr excretion (P < 0.001), (b) (Dpyr/Cr)/BSALP ratio (P < 0.0001) and (c) (Dpyr/Cr)/PICP (P < 0.0001) in the untreated male MM subgroup than controls; (iii) (Dpyr/Cr)/BSALP ratio (P < 0.05) in the untreated than in the responding male MM subgroup, (iv) (Dpyr/Cr)/PICP ratio (P < 0.05) in untreated male patients than in those in the remission subgroup. In conclusion, (a) Dpyr is a sensitive marker in assessment of bone resorption in MM patients; (b) (Dpyr/Cr)/BSALP or (Dpyr/Cr)/PICP ratio is even more sensitive in distinguishing the untreated from the other MM subgroups and controls. Therefore, the use of a combination of these markers may have a potential role in the management of patients with MM.