This is a 24-hour urine collection. N-Telopeptide, urine is used to determine the N-telo/ creatinine ratio, or NTx. This ratio is used in conjunction with clinical evaluation and is referenced against a general baseline in order to assess the probability of a decrease in bone mineral density. Note: This test is intended for one-time use only. If serial monitoring is required, please use the serial monitoring number 511097.