Surface Tension Properties of Human Urine: Relationship with Bile Salt Concentration

Abstract

The surface tension of urine has been simply and rapidly measured using two methods, the DuNouy ring detachment method and the Wilhelmy blade immersion method. The methods agree, the correlation coefficient, r, was 0.992.The effect of ageing of the surface, of storage, of temperature, pH, dilution and albumin on urine surface tension are described.Volume corrected 24 hour urine surface tensions from 6 volunteers over 12 or more days showed variations between individuals of mean surface tensions of 6mN/m (S.D. ± 2.16mN/m). This suggests individual variation in excretion of surface active agents, probably bile salts. This was confirmed by further studies which showed that: 1. Surface tension of urines and rediluted extracts were not significantly different when amphiphilic and hydrophobic solutes including bile salts were extracted from urine and subsequently rediluted in water of the same volume. 2. Bile salt concentration in urine measured by RIA and by enzymatic spectrofluorometric methods correlated well with urine surface tension, r = -0.91, and r == -0.60. 3. Molecular surface area for urinary surfactant was 79 A 2 similar to pure conjugated bile salt solutions calculated from dilution studies.We conclude that the main determinant of urine surface tension is bile salt concentration.

Impact of fouling, cleaning and faecal contamination on the separation of water from urine using thermally driven membrane separation

“…As with real urine, a steady-state flux was achieved, but this was markedly below the productivities of either clean water or real urine. As with the literature (21), surface tension of the urine and faecally contaminated urine were markedly below clean water (72.8 mN m -1 ) at around 56 and 52 mN m -1 respectively (Figure 8).…”

“…around Δγ 20 mN m -1 compared to synthetic urine (around 25%, Figure 8). Mills et al (21) attributed the low surface tension to surface active bile acids which were absent in the synthetic urine composition (20). The reduction in surface tension is proportional to a reduction in breakthrough pressure, indicating an increased probability for membrane wetting (Figure 8, (16)).…”

Inhibition of calcium oxalate precipitation by bile salts

“…24 The clinical relevance of this phenomenon is presently obscure but the activity of BA appeared comparable to that of citric acid (EC 50 = 3.9 ¥ 10 -3 mol/L), 18 the most common drug against urolithiasis. 25 Although BA do not reach mmol/L levels in urine (the normal level, which is < 10 mm, 26,27 increases less than 100-fold in patients with hepatobiliary diseases 27,28 or supplemented with oral BA 29 ), they are known to change the physicochemical properties of this fluid, 30 possibly slowing down the crystal growth process.…”

Rheological and Infrared Spectroscopic Investigations of Normal and Chronic Kidney Disease Urine

“…The healthy normal First morning urine (FMU) and randomly collected urines (RCU) have been collected in clean glass container and kept in a water bath at temperature 37 o C without any preservents and care has been taken that the analysis is to be completed around one hour of collection. These specimens were collected only from male donors to avoid possible contamination from vaginal or perineal squamous epithelial cells 4 .The Chronic kidney disease (CKD) urine was collected from CKD patients at Kidney and Laparoscopic Center, India. All the patients were made aware of the studies and given their consent to use data and urine samples for these studies.…”

“…The change in g is responsible for bubble formation in urine, which can be attributed to kidney disease and changes in Physiological condition of body 3 . The g of urine and effect of bile salts, protein, and temperature and storage time has been investigated 4 . Physical properties of pathological human urine of patients suffering from gallbladder stones and kidney stones along with healthy individuals studied, the density and EC decreases with oxalic acid in urine.…”