Requirement for specific gravity and creatinine adjustments for urinary steroids and luteinizing hormone concentrations in adolescents

Abstract

47 Objectives: 48Urinary hormone concentrations are often adjusted to correct for hydration status. We 49 aimed to determine whether first morning void urine hormones in growing 50 adolescents require adjustments and, if so, whether urinary creatinine or specific 51 gravity (SG) are better adjustments. 52 53 Design and Methods: 54The study population was adolescents aged 10.1 to 14.3 years initially who provided 55 fasting morning blood samples at 0 and 12 months (n=343) and first morning urine 56 every three months (n=644). Unadjusted, creatinine and SG-adjusted hormonal 57concentrations were compared by Deming regression and Bland-Altman analysis and 58 grouped according to self-rated Tanner stage or chronological age. F-ratios for self-59 rated Tanner stages and age groups were used to compare unadjusted and adjusted 60 hormonal changes in growing young adolescents. Correlations of paired serum and 61 urinary hormonal concentration of unadjusted and creatinine and SG adjusted were 62 also compared. 63 64 Results: 65Fasting first morning void hormone concentrations correlated well and were unbiased 66 between unadjusted or adjusted by either creatinine or SG. Urine creatinine 67 concentration increases with Tanner stages, age and male gender whereas, urine SG

Urinary Sex Steroids and Anthropometric Markers of Puberty - A Novel Approach to Characterising Within-Person Changes of Puberty Hormones

“…originally unconjugated plus deconjugated). The details of the novel urine assays have been published [ 24 ]. Briefly, urine and serum specimens were separated by liquid chromatrography using a Shimadzu Nexera UHPLC system (Shmadzu Scientific Instruments, Columbia, MD).…”

Expressing the quantity of urinary analytes: a discussion of some issues arising from the monitoring of the menstrual cycle

“…This correction has been implemented in various ways, but in each case the concentration is normalised to a function of the specific gravity (f(SG)) of the urine. One common form of the specific gravity-corrected concentration is (7) where SG reference = 1.020 for Australian or US samples [10,11], 1.015 for Bangladeshi samples [10] and other values are sometimes used [78]. It is often suggested that samples that are too dilute (SG sample < 1.010) or too concentrated (SG sample > 1.030) should be discarded [72], although this is not always done [11] and other limits are sometimes used [74].…”

“…One common form of the specific gravity-corrected concentration is (7) where SG reference = 1.020 for Australian or US samples [10,11], 1.015 for Bangladeshi samples [10] and other values are sometimes used [78]. It is often suggested that samples that are too dilute (SG sample < 1.010) or too concentrated (SG sample > 1.030) should be discarded [72], although this is not always done [11] and other limits are sometimes used [74]. For example, Gaines et al [75] reported that 63 or 9 of 417 samples (17%) were too dilute (SG < 1.010) or concentrated (SG > 1.030), respectively (it is clear from the distributions reported by these authors that not all of these samples were also excluded based on u Cr ).…”

“…We accept that the least squares approach implies that the uncertainty in s A is negligible, but a similar, albeit more complex, result is obtained when this is not the case using Deming regression, for example. While the use of r in contexts such as this is deprecated for good theoretical reasons [166], it continues to be used and (A1.1) may account for some of the variability in the reported correlations between the serum concentration and urinary levels of reproductive hormones [10,11,108,[110][111][112][113][114]167] for which ds A /dt may be zero, positive or negative. Based on (15), the usual clearance expression (s A dF/dt = J A ) [86] is correct only when ds A /dt = 0 (because F > 0).…”

“…While it is agreed that E1G and PdG are practical urinary analytes to monitor for this purpose, there is some debate about what should actually be measured. In practice, there are at least four common alternatives: (i) the analyte concentration [6,7], (ii) concentration corrected by normalising to the creatinine concentration [10,11], (iii) concentration corrected by normalising to the specific gravity [10,11], or (iv) the analyte excretion rate [3,4,8]. On occasion, urinary analyte concentrations have been corrected by normalising to osmolality [12,13], but this is not common among reports of E1G and PdG levels.…”