Nomograms were developed by Siroky et al for evaluating the urine flow characteristics of elderly men. This can be used to identify and characterize reduced flow in men with urinary tract obstruction, typically benign prostatic hyperplasia. In addition, this can help quantitate the response to surgical or pharmacologic interventions.
Findings:
(1) In normal individuals the urine flow rates depend on the initial bladder volume in a non-linear fashion.
(2) The minimum urine volume that can be assessed for maximum urine flow rate is 50 mL.
(3) Results for average or maximum urine flow more than 2 standard deviations below the mean were associated with obstructive symptoms.
Average Urine Flow (Qave)
average urine flow rate in mL/second =
= (total amount of urine voided in mL) / (number of seconds required to void that volume)
Population characteristics for average urine flow rate for different total urine volumes (where SD = standard deviation from mean):
|
Qave |
50 mL |
100 mL |
200 mL |
300 mL |
400 mL |
500 mL |
|---|---|---|---|---|---|---|
|
+1.0 SD |
10 |
13 |
19 |
22.6 |
25.8 |
28 |
|
+0.5 SD |
8.5 |
11.5 |
17.7 |
20.6 |
23.5 |
25.5 |
|
mean |
7.0 |
10 |
15 |
18.5 |
21 |
22.5 |
|
-0.5 SD |
5.8 |
8.2 |
13 |
16.3 |
18.6 |
20 |
|
-1.0 SD |
4.5 |
7.0 |
11 |
14 |
16.3 |
18 |
|
-1.5 SD |
3.2 |
5.3 |
9 |
12 |
14 |
15.2 |
|
-2.0 SD |
2.0 |
4 |
7.3 |
10 |
11.5 |
13 |
|
-2.5 SD |
1.0 |
2.7 |
5.6 |
7.7 |
9.2 |
10.3 |
|
-3.0 SD |
|
1.2 |
3.6 |
5.2 |
7.0 |
7.8 |
Equations from JMP approximating this data over selected intervals:
|
Qave 0-200 mL |
a * ((volume in mL) ^ 2) |
b * (volume in mL) |
c |
|---|---|---|---|
|
+1.0 SD |
|
0.06 |
7 |
|
+0.5 SD |
|
0.06143 |
5.4 |
|
mean |
|
0.0529 |
4.5 |
|
-0.5 SD |
|
0.048 |
3.4 |
|
-1.0 SD |
|
0.0429 |
2.5 |
|
-1.5 SD |
|
0.0384 |
1.35 |
|
-2.0 SD |
|
0.035 |
0.35 |
|
-2.5 SD |
|
0.030429 |
-0.45 |
|
-3.0 SD |
|
0.024 |
-1.2 |
|
Qave 200-500 mL |
a * ((volume in mL) ^ 2) |
b * (volume in mL) |
c |
|---|---|---|---|
|
+1.0 SD |
-0.000035 |
0.0547 |
9.43 |
|
+0.5 SD |
-0.000022 |
0.04205 |
10.145 |
|
mean |
-0.00005 |
0.06 |
5 |
|
-0.5 SD |
-0.000048 |
0.05655 |
3.595 |
|
-1.0 SD |
-0.000032 |
0.04605 |
3.095 |
|
-1.5 SD |
-0.000045 |
0.0521 |
0.39 |
|
-2.0 SD |
-0.00003 |
0.0396 |
0.64 |
|
-2.5 SD |
-0.000025 |
0.0331 |
-0.01 |
|
-3.0 SD |
-0.00002 |
0.0284 |
-1.34 |
Maximum Urine Flow (Qmax)
Population characteristics for maximum urine flow rate for different total urine volumes (where SD = standard deviation from mean):
|
Qmax |
50 mL |
100 mL |
200 mL |
300 mL |
400 mL |
500 mL |
|---|---|---|---|---|---|---|
|
mean |
12.2 |
16.5 |
22.5 |
26.5 |
28.5 |
29.5 |
|
-0.5 SD |
11.2 |
14.7 |
20 |
23.5 |
25.5 |
26.5 |
|
-1.0 SD |
10 |
13.2 |
17.5 |
20.2 |
22 |
22.6 |
|
-1.5 SD |
8.6 |
11.2 |
14.6 |
16.5 |
18.2 |
19.2 |
|
-2.0 SD |
7.3 |
9.3 |
11 |
13.6 |
14.5 |
15 |
|
-2.5 SD |
6.5 |
7.6 |
9.9 |
10.8 |
11.3 |
11.6 |
|
-3.0 SD |
5.25 |
6.0 |
7.0 |
7.75 |
8.0 |
7.75 |
Equations from JMP approximating this data over selected intervals:
|
Qmax 0-200 mL |
a * ((volume in mL) ^ 2) |
b * (volume mL) |
c |
|---|---|---|---|
|
mean |
-0.000173 |
0.112 |
7.0333 |
|
-0.5 SD |
-0.000113 |
0.087 |
7.1333 |
|
-1.0 SD |
-0.00014 |
0.085 |
6.1 |
|
-1.5 SD |
-0.00012 |
0.07 |
5.4 |
|
-2.0 SD |
-0.000153 |
0.063 |
4.5333 |
|
-2.5 SD |
0 |
0.0227 |
5.35 |
|
-3.0 SD |
-0.000033 |
0.02 |
4.333 |
|
Qmax 200-400 mL |
a * ((volume in mL) ^ 2) |
b * (volume in mL) |
c |
|---|---|---|---|
|
mean |
-0.0001 |
0.09 |
8.5 |
|
-0.5 SD |
-0.000075 |
0.0725 |
8.5 |
|
-1.0 SD |
-0.000045 |
0.0495 |
9.4 |
|
-1.5 SD |
0 |
0.018 |
11.0333 |
|
-2.0 SD |
-0.000085 |
0.0685 |
0.7 |
|
-2.5 SD |
-0.00002 |
0.019 |
6.9 |
|
-3.0 SD |
-0.000025 |
0.02 |
4 |
|
Qmax 400-500 mL |
a * ((volume in mL) ^ 2) |
b * (volume in mL) |
c |
|---|---|---|---|
|
mean |
|
0.01 |
24.5 |
|
-0.5 SD |
|
0.01 |
21.5 |
|
-1.0 SD |
|
0.006 |
19.6 |
|
-1.5 SD |
|
0.01 |
14.2 |
|
-2.0 SD |
|
0.005 |
12.5 |
|
-2.5 SD |
|
0.003 |
10.1 |
|
-3.0 SD |
|
|
8 |
Specialty: Urology
ICD-10: ,
