British Journal of Urobgy (1990), 66,613-614 01990 British Journalof Urology
0007- 1331/90/006f&O613/$I0.00
Caffeine: Does it Affect your Bladder? SARAH M. CREIGHTON and S. L. STANTON Urodynamic Unit, Department of Obstetrics and Gynaecology, !it George‘s Hospital, London
Summary-Patients with symptoms of frequency and urgency often complain that their symptoms are exacerbated by tea or coffee. Aseries of 20 women with confirmed detrusor instability and 10 asymptomatic women were given 200 mg of caffeinecitrate and urodynamic studies were performed. In the group with detrusor instability there was a statistically significant increase in detrusor pressure on bladder filling following administration of caffeine, but no difference in volume at first contraction, height of contraction or bladder capacity. Normal women had no abnormality on cystometry.
Patients with symptoms of urgency and frequency (particularly due to detrusor instability) often complain that these are exacerbated by drinking tea or coffee. Caffeine is a xanthine derivative occurring naturally in tea and coffee. It is known to cause a mild diuresis by acting on the renal tubules to increase renal blood flow and decrease sodium and water reabsorption from the distal tubule in a manner similar to that of thiazide diuretics (Maren, 1961). This may be the reason for the increase in urinary frequency. However, it has long been known that caffeine also acts on skeletal muscle to enhance the capacity for muscular work (Foltz et al., 1942) and increases the resting tension of denervated muscle (Huidobro and Amenbar, 1942). It increases the release of acetylcholine and alters the translocation of intracellular calcium. Caffeine causes smooth muscle relaxation, particularly in the bronchi and vascular tree. Its effect on the detrusor muscle has not been studied and it is possible that it has a direct effect on the detrusor muscle, thus increasing detrusor activity. We have investigated the effect of oral caffeine citrate on 20 patients with known detrusor instability and 10 asymptomatic women to determine whether there is a subjective or objective change in bladder function. Accepted for publication 23 April 1990
Patienits and Methods Twenty patients with detrusor instability proven on urodynamic studies and 10 normal volunteers were asked to take part in the study. All patients with detrusor instability complained that their symptoms were exacerbated by caffeine containing drinks. They were asked to avoid such drinks for 24 h prior to the study. They then underwent routine twin-channel cystometry and uroflowmetry and were asked to attend for repeat urodynamic studies at least 2 weeks later. The delay was to eliminate any “learned response” altering their response to bladdler filling. At this visit they were given 200 mg of caflreine citrate to drink. (A cup of instant coffee contains approximately 85 mg of caffeine (Rall, 1985).Caffeine citrate reaches peak plasma concentrations in 30 to 50 min and has a half-life of 3 to 4 h). Thirty minutes after the administration of the caffeine, urodynamic studies were repeated. The 10 normal volunteers were given 200 mg of caffeine citrate followed by cystometry 30 min later. They did not undergo urodynamics prior to entering the study.
Results Cystometric data for the 2 groups are shown in the Table. A paired t test was used to compare the results in patients with detrusor instability before
613
614
BRITISH JOURNAL OF UROLOGY
Table Cystometric Data
First desire to void (ml) (mean, range) Bladder capacity (ml) Volume at first contraction (ml) Height of maximal contraction (cmHzO) Pressure rise on filling (cmH,O) Pressure rise on standing (cmH,O) Maximum voiding pressure (cmH,O) Peak urinary flow rate (ml/s)
Without caffeine
With caffeine
Normal
148 (48-282) 378 (1 16-699) 280 (80-590) 32 (10-80) 11 (0-25) 11 (0-20) 56 (30-120) 27 (7-40)
136 (36234)* 346 (100-537)* 245 (10450)* 34 (10-70)* 17 ( 0 4 2 ) t (P
0007- 1331/90/006f&O613/$I0.00
Caffeine: Does it Affect your Bladder? SARAH M. CREIGHTON and S. L. STANTON Urodynamic Unit, Department of Obstetrics and Gynaecology, !it George‘s Hospital, London
Summary-Patients with symptoms of frequency and urgency often complain that their symptoms are exacerbated by tea or coffee. Aseries of 20 women with confirmed detrusor instability and 10 asymptomatic women were given 200 mg of caffeinecitrate and urodynamic studies were performed. In the group with detrusor instability there was a statistically significant increase in detrusor pressure on bladder filling following administration of caffeine, but no difference in volume at first contraction, height of contraction or bladder capacity. Normal women had no abnormality on cystometry.
Patients with symptoms of urgency and frequency (particularly due to detrusor instability) often complain that these are exacerbated by drinking tea or coffee. Caffeine is a xanthine derivative occurring naturally in tea and coffee. It is known to cause a mild diuresis by acting on the renal tubules to increase renal blood flow and decrease sodium and water reabsorption from the distal tubule in a manner similar to that of thiazide diuretics (Maren, 1961). This may be the reason for the increase in urinary frequency. However, it has long been known that caffeine also acts on skeletal muscle to enhance the capacity for muscular work (Foltz et al., 1942) and increases the resting tension of denervated muscle (Huidobro and Amenbar, 1942). It increases the release of acetylcholine and alters the translocation of intracellular calcium. Caffeine causes smooth muscle relaxation, particularly in the bronchi and vascular tree. Its effect on the detrusor muscle has not been studied and it is possible that it has a direct effect on the detrusor muscle, thus increasing detrusor activity. We have investigated the effect of oral caffeine citrate on 20 patients with known detrusor instability and 10 asymptomatic women to determine whether there is a subjective or objective change in bladder function. Accepted for publication 23 April 1990
Patienits and Methods Twenty patients with detrusor instability proven on urodynamic studies and 10 normal volunteers were asked to take part in the study. All patients with detrusor instability complained that their symptoms were exacerbated by caffeine containing drinks. They were asked to avoid such drinks for 24 h prior to the study. They then underwent routine twin-channel cystometry and uroflowmetry and were asked to attend for repeat urodynamic studies at least 2 weeks later. The delay was to eliminate any “learned response” altering their response to bladdler filling. At this visit they were given 200 mg of caflreine citrate to drink. (A cup of instant coffee contains approximately 85 mg of caffeine (Rall, 1985).Caffeine citrate reaches peak plasma concentrations in 30 to 50 min and has a half-life of 3 to 4 h). Thirty minutes after the administration of the caffeine, urodynamic studies were repeated. The 10 normal volunteers were given 200 mg of caffeine citrate followed by cystometry 30 min later. They did not undergo urodynamics prior to entering the study.
Results Cystometric data for the 2 groups are shown in the Table. A paired t test was used to compare the results in patients with detrusor instability before
613
614
BRITISH JOURNAL OF UROLOGY
Table Cystometric Data
First desire to void (ml) (mean, range) Bladder capacity (ml) Volume at first contraction (ml) Height of maximal contraction (cmHzO) Pressure rise on filling (cmH,O) Pressure rise on standing (cmH,O) Maximum voiding pressure (cmH,O) Peak urinary flow rate (ml/s)
Without caffeine
With caffeine
Normal
148 (48-282) 378 (1 16-699) 280 (80-590) 32 (10-80) 11 (0-25) 11 (0-20) 56 (30-120) 27 (7-40)
136 (36234)* 346 (100-537)* 245 (10450)* 34 (10-70)* 17 ( 0 4 2 ) t (P
