The authors examined 79 Patients (n=79) with primary and secondary osteoporosis, inc1.31 men (nM =31) aged 31-61 yeara and 48 women (nF =48, aged 33 to 66 years. In these Patients they assessed NTx lamino-terminal telopeptide of type I collagen of the Ist organic bone matrix ) in 24 (NTx24) and 2-hour morning (NTx2) diuresia (from 6 to 8 a.m.). Objective: 1. To asaess the relationship between values of NTx in th suggested 2-hour diuresis and NTx values in the standard 24- hour diuresis differentiated by sex. 2. To compare the ratio (index) of widths of 95% conúdence intervals (CI) for NTx2 and NTx24 with the ratio (index) of reference widths (manuál OSTEX,USA) for NTx in the first morning urine (NTxl) and for NTX24 differentiated by sex. 3. Evaluate the suggested 2-hour diuresis for assessment of NTx. Statistical analysis: Stochastic-determinist linear regression analysis. Results: 1. Between values NTx24 and NTx2 a statistically significant regression correlation was found(p < 0.001) (men: r2 = 0.352, women r2 = 0.781). The indices of widths of reference limits (IR) of OSTEX Co. USA reach values 2.1 times higher (0.7 times) than indices of widths of CI for osteoporosis (IO) in men as well as women. Conclusion: 1. Between values of NTx24 and NTx2 ia a aignificant regression relation. Both urine samples can be used for assessment of the NTx level. 2. Higher valuea of IR and IO indices for women as well as m~n confirm a greater dispersal of NTxl valuea as compared with NTx2 valuea. 3. Introduction of two-hour morning diuresis will reduta the eatent of variation of N1~c valuea during repeated examinations and provide mora accurate information as compared with assessment of NTx in any of the first morning samples of urine according to instrnctions of the manufacturers of the lůts.

        Key words: Osteoreabsorption - Diuresis - Osteoporosis