Objectives:To evaluate the effect of caffeine at the dose of 4.5 mg/kg on bladder function in overactive bladder (OAB) adults.Materials and Methods:Nine women and three men aged 21-40 years with OAB symptoms were included. Each subject drank 8 ml/kg of water with and without caffeine at two separate sessions. Cystometry and uroflowmetry were performed 30 minutes after each drink. The effects of caffeine on urodynamic parameters were compared.Results:After caffeine ingestion, the mean volume at bladder filling phase decreased at first desire to void and normal desire to void (P<0.05), compared to the mean volume after taking water (control) drink. The mean volume at strong desire to void, urgency and maximum cystometric capacity also tended to decrease. No change in the detrusor pressure at filling phase was found. At voiding phase, the maximal flow rate, average flow rate and voided volume were increased (P<0.05). The urine flow time and time to maximal flow rate were not changed.Conclusion:Caffeine at 4.5 mg/kg caused diuresis and decreased the threshold of sensation at filling phase, with an increase in flow rate and voided volume. So, caffeine can promote early urgency and frequency of urination. Individuals with lower urinary tract symptom should avoid or be cautious in consuming caffeine containing foodstuffs.

Caffeine affects many aspects of body function including the gastrointestinal system. A single-blinded experimental study was performed to evaluate the effect of caffeine on lower esophageal sphincter (LES) and esophageal peristaltic contractions in healthy Thai adults. The volunteers were six men and six women aged 19-31 years. Subjects drank 100 mL of water. Five wet swallows were performed 30 min after the drink. The basal LES pressure was continuously measured using esophageal manometric technique. They then consumed another 100 mL of water containing caffeine at the dose of 3.5 mg/kg body weight. The swallows and basal LES pressure monitoring were repeated. The results showed no change in basal LES pressure after a water drink while caffeine consumption significantly lowered the pressure at 10, 15, 20 and 25 min. The mean amplitude of contractions and peristaltic velocity were decreased at the distal esophagus at 3 and 8 cm above LES. The mean duration of contraction was decreased at the distal part but increased at the more proximal esophagus. The heart rate, systolic and diastolic blood pressures were increased significantly at 10-20 min after caffeine ingestion. This study indicated that caffeine 3.5 mg/kg affected esophageal function, resulting in a decrease in basal LES pressure and distal esophageal contraction, which is known to promote the reflux of gastric contents up into the esophagus.

Chronic kidney disease (CKD) is a common health problem worldwide. CKD staging or classification, together with patients' prognosis and treatment plan depend on the patients' kidney function which is assessed by measurement of glomerular filtration rate (GFR). Estimated GFR can be obtained using serum or plasma creatinine as a main variable in equations or formulae such as Cockcroft-Gault equation, MDRD equation (Modification of Diet in Renal Disease), the Schwartz and Counahan-Barratt formulae. These equations, though widely accepted, still have to be adjusted or validated among different groups of patients according to the variation in some factors such as race, diet, and genetic heterogenicity. Diet, especially the high protein load, can affect GFR representing the renal functional reserve. A high protein diet can cause an increase in GFR that lasts for many hours. Long-term consumption of vegetarian diet which is low in protein and contains only protein from plant sources can cause a low baseline GFR while the renal functional reserve is still preserved. This paper aims to remind of the role of protein diet effect on GFR measurement especially when assessing the renal function in vegetarians or individuals on long-term low-protein intake.