Despite the fact that high sodium intake has been linked to high blood pressure and an increased risk for cardiovascular disease (CVD), sufficient and irrevocable evidence to support extremely low dietary sodium intake has been lacking. The best method used for the estimation of daily sodium intake is indirectly by using 24-hour urinary sodium excretion, combined with para-aminobenzoic acid (PABA), which is used for validating completeness of urinary collection. However, the PABA validation method is not favored among researchers and the validity of high-performance liquid chromatography (HPLC) analysis for PABA has not been evaluated in a large-scale study. This study validated an improved PABA HPLC method and applied it in the sub-set of the Prospective Urban Rural Epidemiology (PURE) – 24-hour Urinary Excretion (24USE) Study for the examination of the sodium-blood pressure association. In addition, participants’ self-reported assessment of urinary collection completeness was compared to the PABA method. The HPLC analysis method for measuring PABA levels was downscaled and the reaction time lengthened to achieve higher through-put and reaction yield. By applying the optimized PABA method for evaluating urinary completeness, 612 of 681 participants’ samples contained 70%-110% PABA recovery and were extracted from the PURE24USE Study for further analysis. The average adjusted sodium excretion or intake was 3,673 ± 1,637 mg/day. The participants’ self-reports predict urinary collection completeness as measured by PABA with a sensitivity of 76.9% (95% CI: 74.4%-79.6%) and specificity of 31.7% (95% CI: 27.0%-36.4%). This moderate agreement suggests that PABA still has to be considered the gold standard, until further convincing evidence is available that self-report is more accurate than PABA. / Thesis / Master of Science in Medical Sciences (MSMS)

Majstorović, Z. Utsöndring av stenbildande substanser i urin – kan stickprov er-sätta dygnsmängder? Examensarbete i Biomedicinsk laboratorievetenskap 15 högskolepoäng. Malmö högskola: Hälsa och samhälle, Utbildningsområde Bio-medicinsk laboratorievetenskap, 2011.Syfte. Utredning av njurstenspatienter omfattar alltid undersökning av utsönd-ringen av stenbildande substanser i urin. Samlingen av urin under ett dygn hos njurstenpatienter innebär ofta problem för patienten eftersom det inte är så sällan att de glömmer samla urin i dunken eller samlar för lång eller kort tid. Syftet med min undersökning är att undersöka om det finns alternativ till att samla urin under 24 timmar i de fall där utsöndringen av stenbildande substanser är konstant över dygnet. Frågeställningen är om utsöndringen av stenbildande substanser kan upp-skattas genom att relatera deras koncentration i urin till koncentrationen av kreati-nin i urin eftersom utsöndringen av kreatinin är relativt konstant över dygnet. I så fall bör koncentrationen av stenbildande substanser i urin kunna relateras till kon-centrationen av kreatinin i urin på samma sätt som vid narkotikaanalys. Metod. Försökspersonerna samlade all urin i exakt 24 timmar. Den första urinportionen sparades i ett separat kärl medan all efterföljande urin samlades i en separat dunk . Efter ca en vecka gjordes en ny urinsamling, denna gång bara i en dunk. Dygnsut-söndringarna jämfördes med varandra och med kreatininindex i stickprovet. Re-sultat. Ett starkt samband fanns mellan kreatininindex av kalcium och dygnut-söndringen av kalcium. Sambandet var något mindre starkt för magnesium och saknades för fosfat och kalium. Slutsats. Resultaten talar mot att kreatininindex generellt kan användas för att skatta utsöndringen av njurstensbildande substanser. Däremot verkar kreatininindex relativt väl förutsäga utsöndringen av kalcium och i viss mån även magnesium. / Majstorović, Z. Secretion of stone-forming substances in the urine - can spot urine sample replace 24 hour urine collection? Degree project in Biomedical Laboratory Science, 15 credits points. Malmö University, Health and Society, Department of Biomedical Laboratory Science, 2011.Objective. Clinical investigation of kidney stone patients always includes moni-toring of the secretion of stone-forming substances in the urine. However, 24 h urine collection is difficult for the patient and prone to error. The purpose of this study is to examine whether there are alternatives to the collecting of urine under the period of 24 hours in cases where the secretion of stone-forming substances is constant across days. The question is whether the excretion of stone-forming sub-stances can be estimated by relating the concentration of urine to the creatinine concentration of urine, since the excretion of creatinine is relatively constant over a day. If so, the concentration of stone-forming substances in urine could be relat-ed to the concentration of creatinine in urine in the same way as drug analyses commonly are. Method. The subjects collected a 24h collection of urine. The first urine portion was stored in a container, while all subsequent urine was collected in a separate container. After about a week, another timed collection of urine was performed, but this time only in one container. The 24 h solute excretions were compared to each other and to the solute creatinine index. Results. A strong cor-relation was found between the creatinine index of calcium and the 24 h excretion of calcium. A somewhat weaker correlation was found for magnesium and a lack of correlation for phosphate and potassium. Conclusion. Results indicate that creatinine indexes in general do not predict 24 h excretions. However, creatinine index appears to predict the excretion of calcium and, to some extent, magnesium.

abstract: Urinary sucrose and fructose has been suggested as a predictive biomarker of total sugars intake based on research involving UK adults. The purpose of this study was to determine the association between total sugars consumption and 24-hour urinary sucrose and fructose (24uSF) in US adult population and to investigate the effect of physical activity on this association. Fifty seven free-living healthy subjects 20 to 68 years old, participated in a 15-day highly controlled feeding study, consuming their habitual diet, provided by the research metabolic kitchen. Dietary sugars were estimated using Nutrition Data System for Research (NDSR). Subjects collected eight 24-hour urine samples measured for urinary sucrose and fructose. Physical activity was assessed daily using a validated 15-day log that inquired about 38 physical activities across six domains; home activities, transportation, occupation, conditioning, sports and leisure. The mean total sugars intake and added sugars intake of the sample was 112.2 (33.1) g/day and 65.8 (29.0) g/day (9.7%EI), respectively. Significant moderate positive correlation was found between 15-d mean total sugars intake and 8-day mean 24uSF (r = 0.56, p < 0.001). Similarly, added sugars were moderately correlated with 24uSF (r = 0.56, p < 0.001), while no correlation was found between naturally-occurring sugars and 24uSF (r = 0.070, p < 0.001). In a linear multiple regression, total and added sugars each explained 30% of variability in 24uSF (Adjusted R2, p value; total sugars: 0.297, 0.001; added sugars: 0.301, p < 0.001). Physical activity had no effect on the association between dietary and urinary sugars in neither the correlation nor the linear regression analysis. 24uSF can be used as a biomarker for total and added sugars consumption in US adults, although its predictability was weaker compared to findings involving UK adults. No evidence was found showing that physical activity levels affect the association between 24uSF and total sugars intake in US adults. More detailed investigation through future feeding studies including subjects with wide range of sugars intake and of different ethnic/racial backgrounds are needed to better understand the characteristics of the biomarker and its uses. / Dissertation/Thesis / Masters Thesis Nutrition 2019