Use of Salivary Iodine Concentrations to Estimate the Iodine Status of Adults in Clinical Practice.

BACKGROUND: Measurement of the 24-h urinary iodine concentration or urinary iodine excretion (UIE) is the gold standard to determine iodine status; however, this method is inconvenient. The use of salivary iodine could be a possible alternative since salivary glands express the sodium-iodine symporter. OBJECTIVES: We aimed to establish the correlation between the salivary iodine secretion and UIE, to evaluate the clinical applicability of the iodine saliva measurement. METHODS: We collected 24-h urine and saliva samples from 40 participants ≥18 y: 20 healthy volunteers with no specific diet (group 1), 10 patients with differentiated thyroid cancer with a low dietary intake (<50 µg/d, group 2), and 10 patients with a high iodine status as the result of the use of amiodarone (group 3). Urinary and salivary iodine were measured using a validated inductively coupled plasma MS method. To correct for differences in water content, the salivary iodine concentration (SIC) was corrected for salivary protein and urea concentrations (SI/SP and SI/SU, respectively). The intra- and inter-individual CVs were calculated, and the Kruskal-Wallis test and Spearman's correlation were used. RESULTS: The intra-individual CVs for SIC, SI/SP, and SI/SU were 63.8%, 37.7%, and 26.9%, respectively. The inter-individual CVs for SIC, SI/SP, and SI/SU were 77.5%, 41.6% and 47.0%, respectively. We found significant differences (P < 0.01) in urinary and salivary iodine concentrations between all groups [the 24-h UIE values were 176 µg/d (IQR, 96.1-213 µg/d), 26.0 µg/d (IQR, 22.0-37.0 µg/d), and 10.0*103 µg/d (IQR, 7.57*103-11.4*103 µg/d) in groups 1-3, respectively; the SIC values were 136 µg/L (IQR, 86.3-308 µg/L), 71.5 µg/L (IQR, 29.5-94.5 µg/L), and 14.3*103 µg/L (IQR, 10.6*103-25.6*103 µg/L) in groups 1-3, respectively]. Correlations between the 24-h UIE and SIC, SI/SP, and SI/SU values were strong (ρ = 0.80, ρ = 0.90, and ρ = 0.86, respectively; P < 0.01). CONCLUSIONS: Strong correlations were found between salivary and urinary iodine in adults with different daily iodine intakes. A salivary iodine measurement can be performed to assess the total iodine body pool, with the recommendation to correct for salivary protein or urea.

Diagnostic performance of salivary urea nitrogen dipstick to detect and monitor acute kidney disease in patients with malaria.

BACKGROUND: Acute kidney injury (AKI) is a common complication of malaria. In low resource settings, a lack of diagnostic tools and delayed treatment of malaria associated AKI lead to significant morbidity and mortality. The aim of this study was to assess the diagnostic performance of salivary urea nitrogen (SUN) dipstick to detect and monitor kidney disease [KD = AKI or acute kidney disease (AKD) without AKI] in malaria patients in Angola. METHODS: Patients 11-50 years old admitted with malaria at the Josina Machel (Maria-Pia) Hospital, Luanda, Angola, between 2nd March and 10th May 2016 were enrolled in this study. All participants had serum creatinine (sCr), blood urea nitrogen (BUN) and SUN dipstick tested at the time of recruitment and daily for up to 4 days. AKD without AKI refers to acute renal impairment which do not fulfilled the main criteria for AKI (increases in the baseline serum creatinine and/or decreases in urine output) according defined by the kidney disease improving global outcomes (KDIGO) guideline. RESULTS: Eight-six patients were admitted with malaria diagnosis (mean age 21.5 ± 9.4 years, 71% male) and 27 (32%) were diagnosed with KD. The mean (± SD) sCr and BUN of the KD group at admission (day 0) were 5.38 (± 5.42) and 99.4 (± 61.9) mg/dL, respectively. Three (3.5%) patients underwent haemodialysis and eight (9.3%) died within the first 4 days of hospital admission [5 (62.5%) with KD; 3 (37.5%) without kidney disease; p = 0.047]. The SUN threshold for KD diagnosis was tested pad #5 (SUN > 54 mg/dL). At this threshold, the SUN dipstick had a sensitivity of 67% and specificity of 98% to diagnose KD. The area under the receiver operating characteristics curve (ROC) for KD diagnosis on admission was 0.88 (95% CI 0.79-0.96). The SUN dipstick was most accurate at higher levels of BUN. CONCLUSION: The SUN dipstick had reasonable sensitivity and excellent specificity when used to diagnose KD in a cohort of patients with malaria in a resource-limited setting. Given the severity of presenting illness and kidney injury, the SUN dipstick diagnostic threshold was high (test pad #5). SUN may be used to detect AKI in patients with malaria in low resources settings, thus facilitating earlier access to adequate treatment, which may improve survival.

Can the salivary urea and stimulated saliva concentration be a marker of periodontal diseases in opioid users? A case-control study.

Introduction: & Aim: Microbial plaque is the primary cause of periodontal diseases, and smoking and opioid addiction can accelerate microbial plaque formation and disease progression. Adequate saliva flow and salivary urea concentration are important parameters for a healthy periodontium. In this study, the relationship between Periodontal Diseases and the History of opioid addiction was investigated by measuring the Salivary Urea and Stimulated Saliva Concentration. Materials & methods: This case-control study was conducted on 240 patients (120 cases and 120 controls) in 2021 referred to addiction treatment centers and the dental clinic in Iran, Birjand. The control and case groups were matched in terms of age. Demographic, base data, and clinical examination results were collected by a checklist. Data were analyzed using SPSS 19 and one-way ANOVA and chi-square tests. P-value <0.05 was considered as the significance level. Results: Periodontitis severity was significantly higher in the case group than in the control group (P-value = 0/000). Salivary urea concentration significantly increased in both case and control groups with an increase in periodontitis severity (P-value = 0/003 in the case group and P-value = 0/000 in the control group), but there was no significant relationship between the stimulated saliva flow rate and the severity of periodontitis in these two groups (P-value>0.05). Conclusion: Following the use of opioids, the flow of saliva decreases, and with the exacerbation of the periodontal disease, the concentration of urea in saliva increases. Therefore, it seems that the analysis of saliva parameters, including urea concentration, can be useful for the diagnosis of periodontal disease, and saliva urea concentration is not directly related to opioid use.

Comparison of Serum Urea, Salivary Urea, and Creatinine Levels in Pre-Dialysis and Post-Dialysis Patients: A Case-Control Study.

Background Frequent venepuncture for monitoring of serum urea and creatinine in chronic kidney disease (CKD) patients on dialysis will result in venous damage and infection. In this research, we assessed the feasibility of utilizing salivary samples as a substitute for serum samples in determining the levels of urea and creatinine in patients with CKD undergoing dialysis. Methods The study participants included 50 patients diagnosed with CKD undergoing hemodialysis and an equal number of apparently healthy individuals. We measured the serum and salivary levels of urea and creatinine in normal subjects. CKD patients were also subjected to similar investigations both before and after hemodialysis. Results In our study, we found that the mean value of salivary urea and creatinine are significantly elevated in the case group (salivary urea: 99.56 ± 43.28 mg/dL, salivary creatinine: 1.10 ± 0.83 mg/dL) as compared to the control group (salivary urea: 33.62 ± 23.84 mg/dL, salivary creatinine: 0.15±0.12 mg/dL, p value: <0.001). There was a statistically significant reduction in the mean value of salivary urea and creatinine in the post-dialysis sample (salivary urea: 45.06 ± 30.37 mg/dL, salivary creatinine: 0.43±0.44 mg/dL) compared to the pre-dialysis sample (salivary urea: 99.56 ± 43.28 mg/dL, salivary creatinine: 1.10 ± 0.83 mg/dL; p value: <0.001) in the case group. The salivary urea is significantly positively correlated with serum urea (r value: 0.366, p value: 0.009). But there is no significant correlation seen between salivary and serum creatinine. We have created a cut-off for salivary urea (52.5 mg/dL) to diagnose CKD which has a good sensitivity (84%) and specificity (78%). Conclusion The results of our study suggest that the estimation of salivary urea and creatinine could serve as a non-invasive, alternative marker for the diagnosis of CKD, and benefit in risk-free monitoring of their progress before and after hemodialysis.

A low-cost, portable and easy-operated salivary urea sensor for point-of-care application.

Salivary urea was reported to be a useful biomarker to reflect the blood urea nitrogen in chronic kidney disease patients. However, as a new biomarker, enormous clinical trials are required to define the intended-use and to verify the specification. In this report, we demonstrated a low-cost easy-operated real-time sensing system (optical fiber-urea-sensing, OFUS, system) to detect salivary urea. We aim to make the system easily reproduced by the community to stimulate abundant clinical tests worldwide. The OFUS system is composed of a simple three-dimensional printed tank to link with two optical fibers, one connecting with a commercial light-emitting diode to deliver the input light signal, the other connecting with a commercial cadmium sulfide photo-conductive cell to detect the sensing signal. To allow on-site detection without any sample pretreatment, only 1 µl saliva is needed to be mixed with 10 µl urease solution and 90 µl pH indicator solution in the reaction tank and the detection time is only 20 s. A stable and reproducible calibration curve can be easily built with a detection range as 24-300 mg/dL. The OFUS system successfully detected saliva with added synthetic urea and samples from chronic kidney disease patients. A good agreement between the OFUS system and the commercial kit was obtained. A good correlation between salivary urea and the blood urea nitrogen was also confirmed.

Salivary creatinine and urea in patients with end-stage chronic kidney disease could not be used as diagnostic biomarkers for the effectiveness of dialysis treatment.

INTRODUCTION: End-stage chronic kidney disease (CKD) is characterized by kidney failure with the organ's functions reduced or lost completely, where the kidneys are incapable of filtering excess fluids. Renal replacement therapy may be provided by peritoneal dialysis, hemodialysis or renal transplantation. Among the key indicators for tracking patients' current status are urea and creatinine levels. AIM: The study analyzed saliva as a medium to detect and measure urea and creatinine levels in end-stage CKD patients as well as to use it as criteria for the effectiveness of the dialysis treatment by comparing salivary urea and creatinine levels with their blood levels. MATERIAL AND METHODS: The study targeted 70 end-stage CKD patients from northeastern Bulgaria undergoing hemodialysis treatment. The urea in blood serum was carried out using the UV kinetic method. Creatinine levels were measured using Jaffe reaction colorimetric method without deproteinezation, adapted on an Olympus AU 400 automated biochemical analyzer (Beckman Coulter Inc., USA). Samples from whole unstimulated saliva were collected in a 15 ml sterile test tube as per Navazesh method. The qualitative determination of salivary urea was performed using the UV kinetic method. Creatinine levels in whole unstimulated saliva were measured using Jaffe reaction colorimetric method. RESULTS: There was a statistically significant reduction in blood urea levels (P=0.000) and in blood creatinine levels (P = 0.000) following hemodialysis. The results revealed that there was no statistically significant dependence between both, the urea levels (P=0.240) and the creatinine levels (P=0.065) in whole unstimulated saliva obtained prior to and after a hemodialysis. CONCLUSIONS: Despite the parallel increase of the urea and creatinine levels in blood serum and in whole unstimulated saliva in end-stage CKD, salivary urea and creatinine levels could not be used as diagnostic biomarkers for the effectiveness of dialysis treatment.

A Salivary Urea Nitrogen Dipstick to Detect Obstetric-Related Acute Kidney Disease in Malawi.

INTRODUCTION: Obstetric-related acute kidney injury (AKI) is associated with adverse outcomes for mother and fetus, particularly in low-income countries. However, laboratory-independent tools to facilitate diagnosis are lacking. We assessed the diagnostic performance of a salivary urea nitrogen (SUN) dipstick to detect obstetric-related acute kidney disease in Malawi. METHODS: Women at high risk for AKI admitted to an obstetric unit in Blantyre, Malawi, were recruited between 21 September and 11 December 2015. Patients underwent serum creatinine (SCr) testing alongside measurement of SUN using a dipstick on admission, and every 48 hours thereafter if evidence of kidney disease was found. RESULTS: A total of 301 patients were included (mean age 25.9 years, 11% HIV positive). Of the patients, 23 (7.6%) had AKI, stage 1 in 47.8%, most commonly due to preeclampsia/eclampsia. Mean presenting SCr values were 108.8 ± 21.8 µmol/l (1.23 ± 0.25 mg/dl), 118 ± 34.45 µmol/l (1.33 ± 0.39 mg/dl), and 136.1 ± 30.4 µmol/l (1.54 ± 0.34 mg/dl) in AKI stages 1 to 3 respectively. SUN > 14 mg/dl had a sensitivity of 12.82% and a specificity of 97.33% to detect acute kidney disease; the area under the receiver operating characteristic curve was 0.551. In patients with normal SUN on admission, perinatal mortality was 11.8%, and was 25.0% if SUN was > 14 mg/dl (P = 0.18). CONCLUSION: The SUN dipstick was specific but insensitive when used to diagnose obstetric-related AKI. Limited biochemical derangement and low salivary urea concentrations due to physiological changes in pregnancy, as opposed to a technical limitation of the dipstick itself, are the likely reason for the lack of sensitivity in this study.

Viscous Fingering of Miscible Liquids in Porous and Swellable Media for Rapid Diagnostic Tests.

In lateral flow and colorimetric test strip diagnostics, the effects of capillary action and diffusion on speed and sensitivity have been well studied. However, another form of fluid motion can be generated due to stresses and instabilities generated in pores when two miscible liquids with different densities and viscosities come into contact. This study explored how a swellable test pad can be deployed for measuring urea in saliva by partially prefilling the pad with a miscible solution of greater viscosity and density. The resultant Korteweg stresses and viscous fingering patterns were analyzed using solutions with added food color through video analysis and image processing. Image analysis was simplified using the saturation channel after converting RGB image sequences to HSB. The kinetics of liquid mixing agreed with capillary displacement results for miscible liquids undergoing movement from Korteweg stresses. After capillary filling, there was significant movement of liquid due to these fluidic effects, which led to mixing of the saliva sample with an enzyme test solution. Owing to the simplicity and speed of this test method, urea can be analyzed with an electronic nose over a useful range for detecting salivary urea concentration for rapid and early detection of dehydration.

Analysis of blood and salivary urea levels in patients undergoing haemodialysis and kidney transplant.

AIMS AND OBJECTIVES: To determine correlation between the Salivary Urea levels with that of Blood Urea levels. MATERIALS AND METHODS: Subjects were selected from patients undergoing haemodialysis and patients who had underwent kidney transplantation at Ashwini Hospitals Guntur. The study comprised of 45 patients, of which Haemodialysis group (HD) with 20 patients, Transplant (T) group with 15 patients and 10 patients in control group. Samples of blood and saliva were taken from all the patients to assess the Blood Urea Nitrogen (BUN) and Salivary Urea (SU) levels respectively under strict aseptic precautions. Blood was collected just prior to the dialysis in HD group and in renal transplant (T) patients during their review visit. Informed consent was taken from patients and ethical committee approval taken. RESULTS: There was a statistically significant difference between Blood Urea and Salivary Urea levels in the HD and T group (p<0.05). There was a statistically significant difference between T and Control group with respect to Blood Urea and Salivary Urea levels. The salivary urea levels are slightly higher than blood urea levels in all the study groups. CONCLUSION: The salivary urea tests can be used in place of blood tests as a non invasive diagnostic tool. Thus, preventing the unnecessary and periodic withdraw of blood which is not only cumbersome but also leads to recurrent infections.

Effect of L-arginine dietary supplementation on salivary urea concentration and pH in physically active individuals.

BACKGROUND: The aim of this study was to assess if the consumption of 3 g of a commercially available L-arginine dietary supplement causes a postabsorptive rise in urea concentration or pH of unstimulated saliva in a group of physically active individuals. METHODS: Salivary urea and pH were determined for 117 participants in a randomized double-blinded placebo-controlled study. Samples were collected by 'spitting' method in fasting conditions. One hour prior to their second visit, participants consumed three tablets of L-arginine or placebo. RESULTS: Urea concentration was significantly lower at second measurement for both the study and control group. The magnitude of the change was not significant between the groups. pH was higher for both groups at second measurement, but only significant for the study group. The magnitude of the change was significant between the groups. Participants who intermittently ingested protein dietary supplements and those with a Body Mass Index (BMI) higher than 25 had significantly higher basal urea concentration. CONCLUSIONS: The results of this study did not confirm the hypothesis. Further studies are needed to determine the effects of different doses of L-arginine supplements on the biochemical composition of saliva and the influence of their long-term consumption on the risk of developing dental diseases.

Assessment of periodontal health status in patients undergoing renal dialysis: A descriptive, cross-sectional study.

OBJECTIVE: An inter-relationship between periodontal disease and systemic health has been suspected for centuries, but evidence to explain the connection has only been elucidated in the past few decades. Among the systemic diseases, end stage renal disease has been shown to affect not only the general health of the patient but also oral and periodontal health. This study was undertaken to gain an insight into whether duration of dialysis therapy influences the oral and periodontal health of these patients and also to see if these parameters reflect their biochemical values. MATERIALS AND METHODS: The study was conducted on 75 patients undergoing dialysis and a control group of 25 subjects. The study group was divided into three subgroups depending upon the duration of dialysis. Oral hygiene and periodontal disease status were measured by Simplified Oral Hygiene Index by Greene and Vermillion and Periodontal Disease Index by Ram-fjord. Biochemical parameters measured were blood urea nitrogen and salivary urea levels. Comparison of these parameters was made between the study and control groups through analysis of variance (ANOVA) and student's t-test. RESULTS: Prevalence of periodontal disease was evident in the dialysis group. Oral hygiene status was poor in comparison with the control group. Clinical and biochemical parameters showed statistically significant difference between the groups rather than within the groups. CONCLUSION: Oral and periodontal health appeared to be compromised. Their deteriorating general health is anticipated to cause negligence towards oral health care. This population needs comprehensive oral and periodontal care right from the diagnosis of chronic renal failure. There exists a need for communication between nephrologists and oral health care professionals. Longitudinal studies warranted in this regard.