Monitoring Response to Therapy for Paget's Disease Using Urine Markers of Bone Resorption

 

Specimen collection: usually a 24 hour urine but some can be done on a second morning urine specimen (collected after discarding the first urine on arising)

 

Most of the markers are normalized to creatinine excretion (reported as nmol per mmol creatinine).

 

Compounds measured:

(1) hydroxyproline (only rarely measured today because of lower specificity)

(2) pyridinoline or deoxypyridinoline

(3) collagen telopeptide

 

percent decrease in compound excretion =

= ((previous value) - (current value)) / (previous value) * 100%

Percent Change	Diagnosis
> 25% decrease (some use > 50%)	responder
normalization	complete responder
no change to therapy to <= 25% decrease	nonresponder (resistant)
increase from baseline during therapy	progression
significant decrease lasting >= 2 months without treatment	remission
persistent > 25% increase from nadir	relapse

 

where:

• A negative decrease is an increase.

• Some people use an average of multiple readings to determine baseline and nadir.

• Some people prefer not to use "complete responder", especially when the amount of the compound in the urine is only slightly above normal.