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The use of voided urine temperature in the determination of basal body temperature
FERTILITY AND STERILITY Copyright © 1985 The American Fertility Society
Vol. 44, No.4, October 1985 Printed in U.SA.
The use of voided urine temperature in the determination of basal body temperature
Steven H. Brenner, M.D.* Joseph B. Lessing, M.D. t Richard D. Amelar, M.D.:j: Lawrence Dubin, M.D.:j: Cy Schoenfeld, Ph.D.:j: Laura T. Goldsmith, Ph.D.§ Gerson Weiss, M.D.§II Long Island Jewish-Hillside Medical Center, New Hyde Park, New York, Tel-Aviv Medical Center, Tel-Aviv, Israel, and New York University School of Medicine and Fertility Laboratory, Inc., New York, New York
The recording of daily basal body temperature (BBT) is a routine diagnostic test that many women who undergo infertility evaluation perform. The usual method for obtaining the BBT is for the patient to remain in bed after waking for the time needed to obtain either rectal or oral temperature. Patients sometimes complain about having to remain still with a full bladder while obtaining the temperature reading. This discomfort may lead to noncompliance in properly obtaining the BBT and may compromise accuracy. A method is proposed that uses the temperature of voided
Received March 11, 1985; revised and accepted July 12, 1985. *Division of Reproductive Endocrinology, Long Island Jewish-Hillside Medical Center. tDepartment of Obstetrics and Gynecology A, Tel-Aviv Medical Center, Serlin Hospital, Sackler School of Medicine. :J:Department of Urology, New York University School of Medicine and Fertility Laboratory, Inc. §Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, New York University School of Medicine. IIReprint requests: Gerson Weiss, M.D., Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, New York University School of Medicine, 550 First Avenue, New York, New York 10016.
536
Brenner et aI. Communications-in-brief
urine to plot the BBT. Some patients may find this new method more acceptable. MATERIALS AND METHODS
The patients (two men and four women) were supplied with two oral thermometers (#40-75, Becton-Dickinson, Rochelle Park, NJ), 80-ml paper medicine cups (Lily Medicup #37, Lily, Augusta, GA), and blank BBT charts. Thermometers were tested to read within O.l°F of each other at two different temperatures. Subjects were instructed to obtain their oral temperature on waking in the morning before rising from the bed. After this was accomplished and recorded, the patients walked to the bathroom, took the second thermometer, and placed the thermometer in the empty medicine cup. The subjects were instructed to void 40 ml of urine in the cup and wait 3 minutes before recording the temperature of the voided urine. The BBT graphs from female subjects were transcribed and interpreted by two observers who were unaware of the method used to generate each of the graphs. The scales on the transcribed graphs were left intact, but the exact temperatures were deleted. Oral temperature and voided urine temperature were compared with the use of Fertility and Sterility
100
Q)
~
99
c
~
Q)
a. E
~
98
c
y=0.87x +13.5·.
~
o
r = 0.746 (p
97
96
97
98
<0.0001)
99
100
Urine Temperature Figure 1 Relationship between oral temperature and the temperature of freshly voided urine. The solid line represents the regression line; dotted lines represent the 95% confidence limit; y, oral temperature, x, urine temperature, correlation coefficient, r = 0.746 (P < 0.0001).
Pearson's correlation coefficient and standard linear regression analysis. RESULTS
Two men and four women (five menstrual cycles) recorded 173 pairs of BBTs with the use of voided urine and oral temperature determinations. Forty measurement pairs were obtained with the same thermometer. All temperatures were recorded for the summer months. The mean voided urine temperature was 97.1°F ± 0.038 standard error of the mean (SEM) (n = 173); the mean oral BBT was 97.8°F ± 0.044 SEM (n = 173). The two temperatures were significantly correlated with each other (r = 0.746, P < 0.0001). The regression analysis showed that the relationship between oral temperature (y) and urine temperature (x) was y = 0.87 x + 13.5 (Fig. 1).
The BBT graphs generated by the daily pair of temperature readings paralleled each other and showed that the thermal shift occurred on the same day. DISCUSSION
The temperature of voided urine previously has been found to be significantly related to body temperature and has been proposed to be useful Vol. 44, No.4, October 1985
in the diagnosis of factitial fevers. 1 - 3 Our results confirm this relationship for BBT and demonstrate that the temperature of freshly voided urine obtained at the time of waking can be reliably used to generate BBT graphs. The relationship obtained between voided urine and oral temperature is very close to that obtained by Ellenbogen and Nord. 1 The fact that voided urine temperature is lower than oral temperature is due to the cooling of the urine as the temperature is being recorded. Use of an insulated (Styrofoam) cup to collect the urine may decrease temperature loss. Ambient room temperature will affect this cooling; and although this could be a factor influencing its use for the diagnosis of factitial fevers,4 it would probably not alter the use of urine temperature for BBT. Patients usually obtain their BBTs at home, where the ambient temperature is constant from day to day. The voided urine measurement method may be more acceptable to some patients. On waking, frequently a person's first concern is to void. This method allows the patient to alleviate this urge. Urinating into a cup with an upright thermometer poses a theoretical risk of injury to the external genitalia. If this method is used for obtaining BBT on a routine basis, placing the thermometer into the collection cup immediately after the urine is obtained may be safer. The patient does not need to remain with the urine once it has been deposited into the cup. She may return at a later time to record the temperature, because the highest reading on the thermometer will remain until the thermometer is shaken down. This method allows for the reliable determination of BBT in a way that patients may find more acceptable because it takes little, if any, additional time to perform and does not interefere with the patient's morning routine on waking. This method may be useful for only a few patients but adds another technique to the armamentarium and may be helpful in treating patients who are noncompliant. SUMMARY
The temperature of freshly voided urine has been shown to be a reliable predictor of body temperature. 1 , 2 This relationship was confirmed for the measurement of BBT. A method was described for patients to obtain their BBT in a way that they may find more convenient than obtainBrenner et aI. Communications-in-brief
537
ing either oral or rectal temperature. The BBT graph patterns generated from the temperature of freshly voided urine closely paralleled those generated by oral temperature. REFERENCES
2. Murry H, Tuazon C, Guerrero I, Claudio M, Alliny D, Sheagren J: Urinary temperature a clue to early diagnosis of factitious fever. N Engl J Med 296:23, 1977 3. Fox R, Brook 0, Collins J, Bailey C, Healey F: Measurement of deep body temperature from the urine. Clin Sci Mol Med 48:1,1975 4. Stratton CW: Hot body, cold urine. (Letter to the Editor). N Engl J Med 296:886, 1977
1. Ellenbogen C, Nord B: Freshly voided urine temperature:
a test for factitial fever. JAMA 219:912, 1972
538
Brenner et aI. Communications-in-brief
Fertility and Sterility
Vol. 44, No.4, October 1985 Printed in U.SA.
The use of voided urine temperature in the determination of basal body temperature
Steven H. Brenner, M.D.* Joseph B. Lessing, M.D. t Richard D. Amelar, M.D.:j: Lawrence Dubin, M.D.:j: Cy Schoenfeld, Ph.D.:j: Laura T. Goldsmith, Ph.D.§ Gerson Weiss, M.D.§II Long Island Jewish-Hillside Medical Center, New Hyde Park, New York, Tel-Aviv Medical Center, Tel-Aviv, Israel, and New York University School of Medicine and Fertility Laboratory, Inc., New York, New York
The recording of daily basal body temperature (BBT) is a routine diagnostic test that many women who undergo infertility evaluation perform. The usual method for obtaining the BBT is for the patient to remain in bed after waking for the time needed to obtain either rectal or oral temperature. Patients sometimes complain about having to remain still with a full bladder while obtaining the temperature reading. This discomfort may lead to noncompliance in properly obtaining the BBT and may compromise accuracy. A method is proposed that uses the temperature of voided
Received March 11, 1985; revised and accepted July 12, 1985. *Division of Reproductive Endocrinology, Long Island Jewish-Hillside Medical Center. tDepartment of Obstetrics and Gynecology A, Tel-Aviv Medical Center, Serlin Hospital, Sackler School of Medicine. :J:Department of Urology, New York University School of Medicine and Fertility Laboratory, Inc. §Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, New York University School of Medicine. IIReprint requests: Gerson Weiss, M.D., Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, New York University School of Medicine, 550 First Avenue, New York, New York 10016.
536
Brenner et aI. Communications-in-brief
urine to plot the BBT. Some patients may find this new method more acceptable. MATERIALS AND METHODS
The patients (two men and four women) were supplied with two oral thermometers (#40-75, Becton-Dickinson, Rochelle Park, NJ), 80-ml paper medicine cups (Lily Medicup #37, Lily, Augusta, GA), and blank BBT charts. Thermometers were tested to read within O.l°F of each other at two different temperatures. Subjects were instructed to obtain their oral temperature on waking in the morning before rising from the bed. After this was accomplished and recorded, the patients walked to the bathroom, took the second thermometer, and placed the thermometer in the empty medicine cup. The subjects were instructed to void 40 ml of urine in the cup and wait 3 minutes before recording the temperature of the voided urine. The BBT graphs from female subjects were transcribed and interpreted by two observers who were unaware of the method used to generate each of the graphs. The scales on the transcribed graphs were left intact, but the exact temperatures were deleted. Oral temperature and voided urine temperature were compared with the use of Fertility and Sterility
100
Q)
~
99
c
~
Q)
a. E
~
98
c
y=0.87x +13.5·.
~
o
r = 0.746 (p
97
96
97
98
<0.0001)
99
100
Urine Temperature Figure 1 Relationship between oral temperature and the temperature of freshly voided urine. The solid line represents the regression line; dotted lines represent the 95% confidence limit; y, oral temperature, x, urine temperature, correlation coefficient, r = 0.746 (P < 0.0001).
Pearson's correlation coefficient and standard linear regression analysis. RESULTS
Two men and four women (five menstrual cycles) recorded 173 pairs of BBTs with the use of voided urine and oral temperature determinations. Forty measurement pairs were obtained with the same thermometer. All temperatures were recorded for the summer months. The mean voided urine temperature was 97.1°F ± 0.038 standard error of the mean (SEM) (n = 173); the mean oral BBT was 97.8°F ± 0.044 SEM (n = 173). The two temperatures were significantly correlated with each other (r = 0.746, P < 0.0001). The regression analysis showed that the relationship between oral temperature (y) and urine temperature (x) was y = 0.87 x + 13.5 (Fig. 1).
The BBT graphs generated by the daily pair of temperature readings paralleled each other and showed that the thermal shift occurred on the same day. DISCUSSION
The temperature of voided urine previously has been found to be significantly related to body temperature and has been proposed to be useful Vol. 44, No.4, October 1985
in the diagnosis of factitial fevers. 1 - 3 Our results confirm this relationship for BBT and demonstrate that the temperature of freshly voided urine obtained at the time of waking can be reliably used to generate BBT graphs. The relationship obtained between voided urine and oral temperature is very close to that obtained by Ellenbogen and Nord. 1 The fact that voided urine temperature is lower than oral temperature is due to the cooling of the urine as the temperature is being recorded. Use of an insulated (Styrofoam) cup to collect the urine may decrease temperature loss. Ambient room temperature will affect this cooling; and although this could be a factor influencing its use for the diagnosis of factitial fevers,4 it would probably not alter the use of urine temperature for BBT. Patients usually obtain their BBTs at home, where the ambient temperature is constant from day to day. The voided urine measurement method may be more acceptable to some patients. On waking, frequently a person's first concern is to void. This method allows the patient to alleviate this urge. Urinating into a cup with an upright thermometer poses a theoretical risk of injury to the external genitalia. If this method is used for obtaining BBT on a routine basis, placing the thermometer into the collection cup immediately after the urine is obtained may be safer. The patient does not need to remain with the urine once it has been deposited into the cup. She may return at a later time to record the temperature, because the highest reading on the thermometer will remain until the thermometer is shaken down. This method allows for the reliable determination of BBT in a way that patients may find more acceptable because it takes little, if any, additional time to perform and does not interefere with the patient's morning routine on waking. This method may be useful for only a few patients but adds another technique to the armamentarium and may be helpful in treating patients who are noncompliant. SUMMARY
The temperature of freshly voided urine has been shown to be a reliable predictor of body temperature. 1 , 2 This relationship was confirmed for the measurement of BBT. A method was described for patients to obtain their BBT in a way that they may find more convenient than obtainBrenner et aI. Communications-in-brief
537
ing either oral or rectal temperature. The BBT graph patterns generated from the temperature of freshly voided urine closely paralleled those generated by oral temperature. REFERENCES
2. Murry H, Tuazon C, Guerrero I, Claudio M, Alliny D, Sheagren J: Urinary temperature a clue to early diagnosis of factitious fever. N Engl J Med 296:23, 1977 3. Fox R, Brook 0, Collins J, Bailey C, Healey F: Measurement of deep body temperature from the urine. Clin Sci Mol Med 48:1,1975 4. Stratton CW: Hot body, cold urine. (Letter to the Editor). N Engl J Med 296:886, 1977
1. Ellenbogen C, Nord B: Freshly voided urine temperature:
a test for factitial fever. JAMA 219:912, 1972
538
Brenner et aI. Communications-in-brief
Fertility and Sterility