abstract: Background: Twenty-four hour urinary sucrose and fructose (24uSF) has been developed as a dietary biomarker for total sugars intake. Collection of 24-h urine is associated with high costs and heavy participant burden, while collection of spot urine samples can be easily implemented in research protocols. The aim of this thesis is to investigate the utility of uSF biomarker measured in spot urine. Methods: 15 participants age 22 to 49 years completed a 15-day feeding study in which they consumed their usual diet under controlled conditions, and recorded the time each meal was consumed. Two nonconsecutive 24-hour urines, where each urine void was collected in a separate container, were collected. Four timed voids (morning, afternoon, evening, and next day) were identified based on time of void and meal time. Urine samples were measured for sucrose, fructose and creatinine. Variability of uSF excretion was assessed by coefficient of variation (%CV) and variance ratios. Pearson correlation coefficient and multiple linear regression were used to investigate the association between uSF in each timed void and corresponding 24uSF excretion. Results: The two-day mean uSF was 50.6 mg (SD=29.5) for the 24-h urine, and ranged from 4.5 to 7.5 mg/void for the timed voids. The afternoon void uSF had the lowest within-subject variability (49.1%), and lowest within- to between-subject variance ratio (0.2). The morning and afternoon void uSF had the strongest correlation with 24-h uSF for both mg/void (r=0.80 and r=0.72) and mg/creatinine (r=0.72 and r=0.67), respectively. Finally, the afternoon void uSF along with other covariates had the strongest predictive ability of 24-h uSF excretion (mg/void) (Adjusted R2= 0.69; p=0.002), whereas the morning void had the strongest predictive ability of 24-h uSF excretion (mg/g creatinine) (adjusted R2= 0.58; p=0.008). Conclusions: The afternoon void uSF had the most favorable reproducibility estimates, strong correlation with 24uSF excretion, and explained greatest proportion of the variability in 24uSF. USF in mg/void may be better to use than uSF in mg/g creatinine as a biomarker in spot urine. These findings need to be confirmed in a larger study, and in a study population with a wide range of sugars intake. / Dissertation/Thesis / Masters Thesis Nutrition 2018

Chronic noncommunicable diseases (NCDs) are the largest contributor to mortality rates worldwide including in low- and middle- income countries (LMICs) which already suffer from high rates of infectious disease. Among the four major NCDs that cause 38 million deaths annually, cardiovascular disease (CVD) causes 17.5 million of these annual deaths. The primary risk factor of CVD is hypertension. Kenya, a developing country in Sub-Saharan Africa, has a high rate of hypertension with low (2.6%) management rates. Prior research from our lab has identified a population of Kenyans with a high prevalence of hypertension that is not statistically correlated with typical known risk factors such as obesity, hypercholesterolemia, and behaviors of smoking and lack of exercise. This study investigated the hypothesis that high dietary salt consumption and low K+ dietary intake are contributing to the etiology of high blood pressure in this community. To test our hypothesis, two spot urine samples representing nocturnal excretions (evening and morning) and blood pressure measurements were collected from 135 participants. All samples were analyzed for Na+, K+ and Cl- content using the Smartlyte Electrolyte Analyzer. The average of each spot urine sample was extrapolated to an estimated 24-h value by the method of Mills, et al. The overall population mean urine electrolyte excretion values for Na+, K+ and Cl- were 170.6 ± 89.3 mmol/L, 82.0 ± 54.0 mmol/L, and 87.7 ± 42.1 mmol/L, respectively. While these values fall within the suggested levels for Na+ (40-220 mmol/L) and K+ (25-125 mmol/L), they are under normal excretion levels for Cl- (110-250mmol/L). Overall ion excretion was higher in females than males, although only K+ values were statistically significant (p < 0.05). Analysis of Na+ and Cl- excretion from individuals stratified by blood pressure, revealed significant differences (p < 0.05) between normotensive and hypertensive stage I individuals for both electrolytes (57.9 mmol/L vs. 88.9 mmol/L and 65.5 mmol/L vs. 96.7 mmol/L, respectively). Overall, these results suggest that our sample population consumes dietary salt within a normal range and thus, the observed prevalence of hypertension likely results from other genetic and environmental factors.

The intake of sodium, potassium, and phosphorus has important implications for chronic disease risk. Excess sodium intake is shown to be associated with elevated blood pressure, which in turn is a risk factor for cardiovascular disease (CVD) and chronic kidney disease (CKD). Potassium intake, on the other hand, is shown to be beneficial for lowering blood pressure and reducing the risk of CVD and CKD. Once an individual develops CKD, they experience alterations in mineral metabolism, especially phosphorus, and must closely monitor mineral intake and biochemical laboratory values in order to avoid complications. Thus, monitoring mineral intake is important in both healthy and CKD individuals in both research as well as clinical practice settings. It is therefore also important to have a method for estimating mineral intake that is both accurate as well as easy to administer. Two commonly used methods are self-report and 24-hour urinary mineral excretion. however, both methods have pros and cons. An alternative option that has been explored for all three minerals of interest is to collect a spot urine sample, then use one of several published equations to calculate an estimate of 24-hour urinary mineral excretion. While this method is relatively easy to administer, much remains unexplored regarding the accuracy of estimated 24-hour mineral excretion. My aim for my dissertation was to explore how estimated 24-hour sodium (e24hUNa), potassium (e24hUK) and phosphorus (e24hUP) compared to true mineral intake in healthy participants as well as those with CKD. We conducted secondary analyses from two controlled feeding studies, in which true mineral intake was known. Our results show that e24hUNa and e24hUK are not reliable indicators of true sodium and potassium intake, respectively, in healthy participants nor those with CKD, and e24hUP is not a reliable indicator of phosphorus intake in CKD participants. Though these findings should be confirmed by larger studies, these findings suggest that currently available equations may need to be revised and estimated 24-hour mineral excretion from spot urine samples should be interpreted with caution.

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.