Serum TRACP 5b is a useful marker for monitoring alendronate treatment: comparison with other markers of bone turnover.
We studied clinical performance of serum TRACP 5b and other bone turnover markers, including S-CTX, U-DPD, S-PINP, S-BALP, and S-OC, for monitoring alendronate treatment. TRACP 5b had higher clinical sensitivity, area under the ROC curve, and signal-to-noise ratio than the other markers.


BACKGROUND
The purpose of this study was to compare the clinical performance of serum TRACP 5b (S-TRACP5b) with that of other markers of bone turnover in the monitoring of alendronate treatment.


METHODS
This double-blinded study included 148 healthy postmenopausal women that were randomly assigned into two groups: one receiving 5 mg alendronate daily (n=75) and the other receiving placebo (n=73) for 12 months. All individuals in both groups received calcium and vitamin D daily. The bone resorption markers S-TRACP5b, serum C-terminal cross-linked telopeptides of type I collagen (S-CTX), and total urinary deoxypyridinoline (U-DPD), and the serum markers of bone formation procollagen I N-terminal propeptide (S-PINP), bone-specific alkaline phosphatase (S-BALP), and total osteocalcin (S-OC) were assessed at baseline and at 3, 6, and 12 months after initiation of treatment. Lumbar spine BMD (LBMD) was measured at baseline and 12 months.


RESULTS
Compared with the placebo group, LBMD increased, and all bone markers decreased significantly more in the alendronate group (p<0.001 for each parameter). The decrease of S-TRACP5b after first 3 months of alendronate treatment correlated significantly with the changes of all other markers except S-OC, the best correlation being with S-CTX (r=0.60, p<0.0001). The changes of LBMD at 12 months only correlated significantly with the changes of S-TRACP5b (r=-0.32, p=0.005) and S-CTX (r=-0.24, p=0.037) at 3 months. Based on clinical sensitivity, receiver operating characteristic (ROC) curves, and signal-to-noise ratio, S-TRACP5b, S-CTX, and S-PINP were the best markers for monitoring alendronate treatment. Clinical sensitivity, area under the ROC curve, and signal-to-noise ratio were higher for S-TRACP5b than for the other markers.


CONCLUSIONS
These results show that S-TRACP5b, S-CTX, and S-PINP are useful markers for monitoring alendronate treatment.
Nenonen
Arja
A
Rheumatism Foundation Hospital, Heinola, and Department of Clinical Chemistry, University Hospital of Tampere, Finland.
Cheng
Sulin
S
Ivaska
Kaisa K
KK
Alatalo
Sari L
SL
Lehtimäki
Terho
T
Schmidt-Gayk
Heinrich
H
Uusi-Rasi
Kirsti
K
Heinonen
Ari
A
Kannus
Pekka
P
Sievänen
Harri
H
Vuori
Ilkka
I
Väänänen
H Kalervo
HK
Halleen
Jussi M
JM
D000135:Acid Phosphatase / Q000097:blood*; D019386:Alendronate / Q000008:administration & dosage*; D015415:Biomarkers / Q000097:blood; D050071:Bone Density Conservation Agents / Q000008:administration & dosage*; D002118:Calcium / Q000008:administration & dosage; D004311:Double-Blind Method; D016903:Drug Monitoring; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000097:blood*; D008875:Middle Aged; D010012:Osteogenesis / Q000187:drug effects; D017698:Postmenopause / Q000097:blood*; D000071681:Tartrate-Resistant Acid Phosphatase; D014807:Vitamin D / Q000008:administration & dosage
D015415:Biomarkers; D050071:Bone Density Conservation Agents; D007527:Isoenzymes; D014807:Vitamin D; C000605510:ACP5 protein, human; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D002118:Calcium; D019386:Alendronate