Biomedical subjects

W H Pan

Publications and source records attributed to W H Pan.

At least 55 records · Page 3Linked to original sources

PubMed1995

Determination of microdialysis extraction fraction of cocaine by the no net flux method under high, low, and zero steady-state cocaine concentrations in rats.

The effect of different steady-state cocaine concentration maintenance on the microdialysis extraction fraction of cocaine (in situ recovery; Ed) in the medial prefrontal cortex (mPFC) was examined. Male, adult Sprague-Dawley rats anesthetized with chloral hydrate were used. All rats were randomly divided into three groups and were given cocaine i.v. infusion of either 0.6 mg/kg/min (group A), 0.3 mg/kg/min (group B), or 0.0 mg/kg/min (group C). A steady-state cocaine concentration in the blood was obtained for both A and B groups. They were 24.3 +/- 2.3 microM, respectively. We then applied the no net flux microdialysis method to determine the Ed of cocaine in vivo for all three groups. Results revealed that there was no significant difference of Ed under these three different infusion regimens (group A: 16 +/- 2%; group B: 17 +/- 1%; group C: 21 +/- 2%). The steady-state cocaine concentration in the mPFC was also estimated to be 17.7 +/- 1.3 microM, 11.3 +/- 2.0 microM, and 0.7 +/- 0.6 microM, respectively. We then concluded that the Ed of cocaine in the mPFC is invariable while the steady-state cocaine concentration in the mPFC was ranging from 0 to 18 microM. This information is useful in the cocaine pharmacokinetic study since scientists are concerned about the variations of Ed while cocaine concentration in the mPFC is changing.

Animals↗

PubMed1995

Increased sympathetic nervous system activity in Chinese hypertensive patients with type II diabetes mellitus.

To evaluate the coexistence of sympathetic overactivity and hypertension in type 2 diabetic patients, a population-based study was conducted of newly-diagnosed type 2 diabetic patients recruited from a single community located at northern Taiwan. This study included 2877 (male 1382, female 1495) middle-aged ethnic Chinese adults, aged 45-65 years. Of the 1382 males, 67 had newly-diagnosed type 2 diabetes mellitus, whereas 75 of the 1495 females had type 2 diabetes. The data showed that about 39% of diabetic patients had borderline hypertension (mean blood pressure 141/91 mmHg) whereas the average incidence in non-diabetic subjects was 15.5%. The borderline hypertensive diabetic patients had significantly higher heart rates (mean 78.8 vs. 69.3 beats/min; P < 0.001) than control subjects. However, the cardiac index was similar in both control and diabetic subjects (mean 2.48 vs. 2.53 l/min/m2; P > 0.05). Our data show that sympathetic overactivity and increased incidence of hypertension actually existed in these type 2 diabetic patients of Chinese origin.

Analysis of Variance↗

PubMed1995

Vegetable consumption, serum retinol level, and risk of hepatocellular carcinoma.

A cohort of 8436 men in Taiwan was recruited with personal interview and blood sample collection between 1984 and 1986. During the 5-year follow-up period, 50 incident cases of hepatocellular carcinoma (HCC) were identified. Retinol levels were measured for 35 HCC patients whose serum samples were available and 140 matched controls randomly selected from cohort members without HCC. Lower vegetable intake was significantly associated with an increased risk of HCC after adjustment for other HCC risk factors (P = 0.006). The effect of low vegetable intake on HCC risk was limited to hepatitis B virus chronic carriers and cigarette smokers. As compared with subjects who had a weekly vegetable consumption frequency of six or more meals, the multivariate-adjusted relative risk of HCC for subjects who had a frequency of less than six meals was 4.7 (95% confidence interval, 2.0-11.1; P = 0.0004) among chronic hepatitis B virus carriers and 3.8 (95% confidence interval, 1.7-8.5; P = 0.001) among cigarette smokers. There was an inverse dose-response relationship between the prediagnostic serum retinol level and the development of HCC (trend test, P = 0.003). The odds ratio of HCC for men with a retinol level in the lowest tertile was 9.0 (95% confidence interval, 2.1-39.1) compared with those with a level in the highest tertile. The relation remained after multivariate adjustment for cigarette smoking, habitual alcohol drinking, and either the seropositivity of hepatitis B virus surface antigen and/or anti-hepatitis C virus antibody or the past history of liver diseases through conditional logistic regression analysis. The association was more striking for men 55 years or younger and for those who smoked 10 or more cigarettes/day. There was a significant synergistic effect of hepatitis B virus surface antigen carrier status and low serum retinol level on the development of HCC. These data suggest a potential role of retinol in the chemoprevention of HCC.

Adult↗

PubMed1995

Temperature extremes and mortality from coronary heart disease and cerebral infarction in elderly Chinese.

We studied the relation between outdoor temperature and mortality rates from cardiovascular disease in Taiwan from 1981 to 1991. In 11 years, there were 30,085, 21,750, and 39,818 deaths from coronary artery disease, cerebral infarction, and cerebral haemorrhage, respectively, among 7.6 million residents aged 25 and over in selected areas where climate was recorded. A temperature-mortality relation was especially apparent in the elderly. A U-shaped relation was observed between temperature and mortality from coronary artery disease and cerebral infarction. The range corresponding to least deaths from coronary artery disease (26-29 degrees C) and cerebral infarction (27-29 degrees C) was higher than that in countries with colder climates. In the elderly, the risk of cerebral infarction at 32 degrees C was 66% higher than that at 27-29 degrees C; the risk increased by 3.0% per 1 degree C reduction from 27-29 degrees C. The risk of coronary artery disease at 32 degrees C was 22% higher than that at 26-29 degrees C; below 26-29 degrees C, the risk increased by 2.8% per 1 degree C reduction. Mortality from cerebral haemorrhage decreased with increasing temperature at a rate of 3.3% per 1 degree C. These results imply a pathophysiological difference between thromboembolic and haemorrhagic cardiovascular diseases. Poor thermoregulation in older people may precipitate cardiovascular disease events.

Adult↗

PubMed1995

Anesthetics decreased the microdialysis extraction fraction of norepinephrine but not dopamine in the medial prefrontal cortex.

We evaluated the effects of chloral hydrate and pentobarbital sodium on the basal extracellular concentrations of dopamine (DA) and norepinephrine (NA) as well as their in vivo extraction fraction (relative recovery) at the medial prefrontal cortex (mPFC) in rats by using zero-net flux microdialysis method. Adult, male Sprague-Dawley rats anesthetized with either chloral hydrate (400 mg/kg, i.p., with 80 mg/kg i.v. supplements) or pentobarbital sodium (50 mg/kg, i.p., with 10 mg/kg i.v. supplements) were used as treatment groups. Conscious rats were used as a control group. The basal extracellular concentration and in vivo recovery of DA in the conscious group were 2.38 +/- 0.70 nM and 41 +/- 6%. In comparison with the chloral hydrate group (1.51 +/- 0.55 nM and 41 +/- 9%) and the pentobarbital sodium group (2.81 +/- 1.20 nM and 42 +/- 4%), there were no significant effects of anesthesia on the basal extracellular concentration and the in vivo recovery of DA at the mPFC. Additionally, the basal extracellular concentration and the in vivo recovery of NA in the conscious group were 1.59 +/- 0.37 nM and 51 +/- 8%. There also were no significant differences of the basal extracellular concentration of NA among these three groups (chloral hydrate group: 4.38 +/- 1.39 nM; pentobarbital group: 3.67 +/- 0.90 nM). However, the conscious group had a higher in vivo recovery than the two anesthetized groups (chloral hydrate group: 16 +/- 2%; pentobarbital group: 27 +/- 5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthetics↗

PubMed1995

Plasma lipid profiles and epidemiology of atherosclerotic diseases in Taiwan--a unique experience.

Rapid economic growth in Taiwan is accompanied by changing lifestyles, and the mortality pattern has switched from predominantly infectious diseases to chronic diseases. Age-adjusted mortality from heart disease has increased slowly but steadily. However, mortality from heart disease in Taiwan remains low compared with many other countries. Mortality from the cerebrovascular diseases has decreased gradually. Current age- and sex-specific values of blood cholesterol low density lipoprotein cholesterol (LDL-C) and triglyceride (TG) are, in general, higher than values in mainland China, but lower than those in the NHANES III and PROCAM studies. From 1950 to 1987, percent dietary fat increased from 16% to 36% in Taiwan. However, a high polyunsaturated fat/saturated fat (P/S) ratio (1.3) maintained during this period may in part explain the favorable blood lipid status and low mortality from heart disease. Data from prospective studies are scarce. In case-control studies carried out in Chinese, significantly higher values of TG, CHOL LDL-C, but lower high density lipoprotein cholesterol (HDL-C) levels have often been found in coronary artery disease (CAD) patients than in controls. The percent differences in TG and HDL-C values (20%) were much greater than those of CHOL and LDL-C (3%). A few studies have identified the TG level as an independent risk factor for stroke and CAD in Taiwan, where a moderate to high fat diet with an advantageous P/S ratio is consumed.

Adult↗

PubMed1995

The effectiveness and safety of low dose pravastatin in elderly hypertensive hypercholesterolemic subjects on antihypertensive therapy.

To evaluate the efficacy and safety of low dose (10 mg) pravastatin in hypercholesterolemic, hypertensive elderly subjects undergoing antihypertensive treatment, a randomized, double-blind, placebo-controlled 6-month trial was conducted. The subjects had a total plasma cholesterol of at least 250 mg/dL and had been, for at least 3 months, consuming a standard lipid-lowering diet (American Heart Association Step 1 Diet). Sixty elderly hypertensive patients randomly received placebo (n = 30) or pravastatin (n = 30) treatment. The dosage consisted of 10 mg of pravastatin daily during the 6-month trial. Over that period, in the pravastatin group, plasma levels of total cholesterol and LDL-cholesterol significantly (P < .01) dropped (-20% and -25%, respectively) compared to the placebo group. The plasma level of HDL-cholesterol increased (+5%) while triglycerides slightly decreased (-8%) (P < .05). No serious side effects occurred, and pravastatin was generally tolerated. Fasting hyperinsulinemia (11.0 +/- 0.8 v 9.3 +/- 0.7 microU/mL; P = .06) also improved, although not significantly, after 6 months of pravastatin therapy. Results from this study confirmed that a low dose (10 mg) of pravastatin daily is a safe and effective method of reducing plasma total and LDL-cholesterol in hypercholesterolemic, hypertensive elderly patients who are on concurrent antihypertensive drug therapy.

Aged↗

PubMed1995

Differential effects of chloral hydrate and pentobarbital sodium on a cocaine level and its catecholamine response in the medial prefrontal cortex: a comparison with conscious rats.

Adult male Sprague-Dawley rats anesthetized with chloral hydrate and pentobarbital sodium were used as two different treatment groups. Conscious rats were used as a control group. By using baseline (precocaine) concentration as 100%, after cocaine administration (3.0 mg/kg i.v.), the maximal dopamine (DA) increase occurring at the first microdialysis collection period (20 min) in the medial prefrontal cortex was 299 +/- 46% for the chloral hydrate group, 168 +/- 12% for the pentobarbital sodium group, and 325 +/- 23% for the conscious group. At the same time, norepinephrine (NA) increases reached a maximum and were 162 +/- 20%, 100 +/- 5%, and 141 +/- 17%, respectively. The maximal changes of DA and NA in the chloral hydrate group and in the control group were both significantly higher than that in the pentobarbital sodium group. Meanwhile, the cocaine concentration was higher over a 100-min period of time in the chloral hydrate group when compared with the pentobarbital group and the control group. The peak cocaine concentration in dialysate occurred in the same time slot of maximal DA and NA responses, which were 0.65 +/- 0.08, 0.30 +/- 0.02, and 0.41 +/- 0.05 microM, respectively. Anesthetics suppress the pharmacologic response of neurons, which may explain the difference in catecholamine response between the pentobarbital sodium and the conscious groups. Conversely, because there was no significant difference in DA and NA response between the chloral hydrate group and the conscious group, it may possible be due to the balancing effect between the higher existing cocaine concentration and the anesthetic suppression on pharmacological response of neurons in the chloral hydrate group. The effect of guide cannula implantation on the cocaine-induced catecholamine response was also evaluated.

Anesthesia↗

PubMed1995

A vegetarian diet rich in soybean products compromises iron status in young students.

The iron status of young Chinese Buddhist vegetarians (23 men and 32 women) and nonvegetarian students (20 men and 39 women from a medical college) was investigated by dietary assessment of iron intake and hematological measurement of biochemical indices including hemoglobin, plasma iron, transferrin, transferrin saturation and plasma ferritin. A characteristic of the vegetarian diet in this study was the replacement of meat by soybean products. Results of the dietary assessment showed that the average iron density of the diets ranged from 1.9 to 2.2 mg/MJ, with no difference between the vegetarian and nonvegetarian diets. Daily iron intake was similar in both vegetarian and nonvegetarian men. However, iron intake was significantly higher in female vegetarians than nonvegetarians, averaging 104 and 78% of the RDA, respectively. Results of blood analysis showed that, for both sexes, the median plasma ferritin concentration of the vegetarians (male 47 micrograms/L and female 12 micrograms/L) was about half the level of the nonvegetarians (male 91 micrograms/L and female 27 micrograms/L). Occurrence and risk of iron deficiency are more prevalent in vegetarians. Correlation between plasma ferritin concentration and years of vegetarian practice in vegetarian men was marginally significant (r = -0.38, P = 0.077). We conclude that a vegetarian diet that is rich in soybean products and restricted in animal foods is limited in bioavailable iron and is not adequate for maintaining iron balance in men and women.

Adult↗

PubMed1995

Coagulation activation in type 2 diabetes mellitus: the higher coronary risk of female diabetic patients.

Thrombophilia in diabetic patients is a well-recognized phenomenon which constitutes an additional risk of coronary heart disease. This study included 1980 ethnic Chinese people (835 male, 1145 female); age range: 45 to 69 years, including 280 Type 2 diabetic patients (male 125, female 155). Haemostatic parameters measured were fibrinogen, prothrombin time, activated partial thromboplastin time (APTT), factor VIIc, factor VIIIc, antithrombin III, and plasminogen. Compared with a control group, male diabetic patients showed significantly shorter APTT (25.6 +/- 3.7 vs 27.5 +/- 3.6 s, p < 0.001), and elevated factor VIIIc (171.1 +/- 77.48 vs 131.16 +/- 52.23%, p < 0.0001), whereas female diabetic patients showed significantly shorter APTT (24.9 +/- 4.2 vs 26.5 +/- 3.9 s, p < 0.001) and elevated fibrinogen (10.6 +/- 3.3 vs 9.8 +/- 2.6 mumol 1(-1), p < 0.05), factor VIIc (150.4 +/- 68.7 vs 135.3 +/- 32.3%, p < 0.001), factor VIIIc (190.1 +/- 92.6 vs 141.1 +/- 62.4%, p < 0.0001), and plasminogen (140.3 +/- 41.9 vs 128.4 +/- 38.7%, p < 0.01). This study showed that Chinese diabetic patients had coagulation activation, and that female diabetic patients seemed to constitute a higher risk group for coronary heart disease than males.

Aged↗

PubMed1995

Thrombophilia associated with obesity in ethnic Chinese.

OBJECTIVE: To investigate a possible interrelationship between obesity and the coagulation and fibrinolytic systems of ethnic Chinese. DESIGN: The Cardiovascular Disease Risk Factor Two-Township Study, a longitudinal, prospective study in Taiwan, which focuses on the evolution of cardiovascular disease risk factors. MEASUREMENTS: Haemostatic parameters measured in this study included prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, factor VIIc, factor VIIIc, antithrombin III and plasminogen. RESULTS: Present data demonstrated that all haemostatic parameters show a dose-dependent change with body weight. PT and APTT shortened with increased body mass index (BMI). Fibrinogen, factor VIIc, factor VIIIc, plasminogen and antithrombin III increased with higher BMI. CONCLUSION: The present result shows that haemorrheological abnormalities do exist in obese subjects and this thrombophilic phenomenon sheds further light on the study of higher cardiovascular and cerebrovascular mortality and morbidity in the obese.

Adult↗

PubMed1994

Participation of noradrenergic neurotransmission in the suppression by substance P of alpha 2-adrenoceptors at the nucleus reticularis gigantocellularis involved in central cardiovascular regulation in the rat.

We applied reverse microdialysis and HPLC analysis to quantify the participation of noradrenergic neurotransmission in the modulation by substance P of alpha 2-adrenoceptors at the nucleus reticularis gigantocellularis involved in cardiovascular regulation, using Sprague-Dawley rats anesthetized with pentobarbital sodium. The efficacy of circulatory suppression of a centrally acting alpha 2-adrenoceptor agonist, guanabenz, was used as the experimental index. Continuous infusion of substance P (600 or 1200 pmol/microliters/min) into the nucleus reticularis gigantocellularis through a stereotaxically positioned microdialysis probe (active exchange length: 500 microns, diameter: 220 microns) for 80 min elicited a reduction in the hypotensive and bradycardiac actions of guanabenz (100 micrograms/kg, i.v.). This implied suppression of alpha 2-adrenoceptor activity correlated positively with the time-course of increase in the estimated extracellular concentration of the undecapeptide and norepinephrine in the nucleus reticularis gigantocellularis. Experimentally elevating the concentration of norepinephrine at this reticular nucleus via microinfusion by reverse microdialysis also decreased the efficacy of the cardiovascular suppression of the aminoguanidine compound. These results suggest that substance P may depress the activity of the alpha 2-adrenoceptors in the nucleus reticularis gigantocellularis that are involved in central cardiovascular regulation via an increase in the extracellular concentration of norepinephrine at this reticular nucleus.

Adrenergic alpha-Antagonists↗

PubMed1994

Power spectral analysis of electroencephalographic desynchronization induced by cocaine in rats: correlation with microdialysis evaluation of dopaminergic neurotransmission at the medial prefrontal cortex.

We evaluated the effect and action mechanisms of cocaine on electroencephalographic (EEG) activity in adult male Sprague-Dawley rats anesthetized with chloral hydrate (400 mg/kg, i.p., with 80 mg/kg/h supplements). On-line and real-time power spectral analysis of the EEG activity continuously quantified its root mean square (RMS) and mean power frequency (MPF) values, and the power of its spectral frequency components (low frequency: 0-4 Hz; high frequency: 4-20 Hz). Administration of cocaine (1.5 or 3.0 mg/kg, i.v.) dose-dependently induced EEG desynchronization, as manifested by a reduction in RMS and an elevation in MPF values, coupled with a differential decrease in both high and low frequency components. Samples collected by in vivo microdialysis at the medial prefrontal cortex (mPFC) and analyzed by HPLC showed that the elevation of cocaine and dopamine (DA) level in the dialysate reached its peak during the time interval when maximal activation of EEG occurred. This EEG activation was antagonized by microinfusion into the mPFC via reverse microdialysis of R(+)-SCH 23390, a selective antagonist for D-1 receptors; sulpiride, a selective antagonist for D-2 receptors; or haloperidol, a nonspecific dopamine antagonist. These results suggest that dopaminergic neurotransmission at the mPFC may be intimately related to the specific spectral pattern of alteration in EEG activity elicited by cocaine in the rat and that both D-1 and D-2 receptors may be involved in the process.

Animals↗

PubMed1994

Differential effects of chloral hydrate and pentobarbital sodium on cocaine-induced electroencephalographic desynchronization at the medial prefrontal cortex in rats.

We evaluated the effects of two anesthetics on the cocaine-induced electroencephalographic (EEG) desynchronization in male, Sprague-Dawley rats. One group was anesthetized with chloral hydrate (400 mg/kg, i.p., 80 mg/kg/h i.v. supplement; group A). The other group was anesthetized with pentobarbital sodium (50 mg/kg, i.p., 10 mg/kg/h i.v. supplement; group B). The degree of EEG desynchronization after cocaine administration (1.5 mg/kg, i.v.) was expressed as an increase in the mean power frequency (MPF) and a decrease in the root mean square (RMS). These maximal increases and decreases were observed to be larger in group A (MPF: 43.3 +/- 7.0% increase; RMS: 47.4 +/- 5.0% decrease) than in group B (MPF: 17.8 +/- 3.6% increase; RMS: 19.2 +/- 2.5% decrease). Our laboratory previously proved that dopaminergic neurotransmission at the medial prefrontal cortex (mPFC) participated in the cocaine-induced EEG desynchronization and that both D-1 and D-2 receptors were involved in the process. Therefore, in vivo microdialysis coupled with high performance liquid chromatography was used to quantify the changes of extracellular dopamine (DA) concentrations at the mPFC for 90 minutes at 10 minute intervals after 1.5 mg/kg cocaine i.v. injection. The extracellular DA increases in both groups was rapid and reached the maximal peak within 10 min. There was no significant difference in the maximal increase of DA between groups (group A: 375.2 +/- 35.77% versus group B: 332.2 +/- 16.69% over basal value). These results suggest that different anesthetics may differentially affect cocaine-induced EEG desynchronization and this difference has no bearing on the DA response in the mPFC.

Animals↗

PubMed1994

Difference in extracellular cocaine concentration between the ventral tegmental area and the medial prefrontal cortex following intravenous administration as revealed by quantitative microdialysis coupled with in vivo calibration.

Two microdialysis probes (active length: 1 mm) were simultaneously lowered into the ventral tegmental area (VTA) and the medial prefrontal cortex (mPFC) of each male, adult Sprague-Dawley rat, anesthetized with chloral hydrate, to evaluate whether cocaine distribution between these two areas is uniform after i.v. injection of 3 mg/kg cocaine. Using a modified in vivo calibration method, we can estimate the extracellular cocaine concentration in those nuclei. This proposed calibration method offers the advantages of simplicity and speed. Measurement of the cocaine concentration in the dialysate and estimation of the extracellular cocaine concentration showed that extracellular cocaine in the VTA was significantly higher than that in the mPFC. Next, the active length of the dialysis probe was extended to 4 mm in order to examine the effect of the active probe length on the cocaine distribution profile between the mPFC and a mixed area of VTA and red nucleus. Surprisingly, the cocaine concentration in dialysate had a contradictory result compared to the extracellular cocaine concentration due to in vivo recovery in the mPFC (25.3 +/- 3.1%) which was significantly higher than that in the mixed area (17.5 +/- 1.6%). Firstly, these results suggest that distribution of cocaine following systemic administration was not uniform in the rat brain. Secondly, in a valid comparison of drug concentrations between the two dialysis areas, we must consider the in vivo recovery for each brain region.

Animals↗

PubMed1994

Curvilinear relations between age and hemostatic parameters in Chinese.

The role of hemostatic factors in the pathogenesis of cardiovascular disease has gained much attention recently. Information about hemostatic factors, and their age patterns is sparse for orientals. With the data collected in the Cardiovascular Disease Risk Factor Two-township Study in Taiwan, this study shows that, in general, the older the age, the stronger the tendency toward thrombosis. With advancing age, prothrombin time, activated partial thromboplastin time, and antithrombin-III level decreased steadily; but mean values of fibrinogen, factor VIIc, and factor VIIIc increased. Gender differences in the age patterns of the above factors are carefully described. Curvilinear relations between hemostatic factors and age were demonstrated for adults aged 18 and above for all hemostatic factors studied. This curvilinearity should be taken into consideration when adjusting for the effect of age in data analysis to avoid residual confounding, particularly when the age range of the study subjects is wide.

Adolescent↗

PubMed1994

Correlates and predictive models for blood pressure values in residents of two communities in Taiwan.

Factors predicting systolic blood pressure (SBP) and diastolic blood pressure (DBP) were extensively studied in residents aged 18 years and above from 10 villages in two Taiwanese communities. In women, the associated factors identified included age, body mass index, waist/hip ratio (not selected as a factor for DBP), plasma uric acid, plasma chloride, urinary sodium/creatinine ratio, urinary calcium/creatinine ratio, education level, ancestral origin, parental hypertension status, and marital status. In men, the factors were age, body mass index, plasma triglyceride concentration, urinary sodium/creatinine ratio, smoking status, alcohol drinking status, parental hypertension status (not selected for DBP), and marital status (not selected for DBP). The degree of BP variation which could be significantly explained by the measured factors differed between SBP and DBP, and differed between men and women: 18% in men and 39% in women for SBP variation; 15% in men and 27% in women for DBP variation. Factors other than those included in the models should be explored, particularly for men. This study identifies, for Chinese populations, predictive factors of BP well-known in Western societies (BMI, urinary sodium, plasma uric acid, alcohol consumption) and factors less emphasized in other studies (plasma triglyceride and marital status). A positive association between BP and urinary Na, a lack of association between BP and urinary K, and opposite findings in the relationship between BP and the education level for men (positive relation) and women (negative relation) are worth noting.

Adolescent↗

PubMed1994

Diurnal electrolyte excretion pattern affects estimates of electrolyte status based on 24-hour, half-day, and overnight urine.

This study set out to examine the diurnal pattern of electrolyte excretion in urine, and to investigate whether urine collected from after dinner until next morning (half-day evening urine) might to be an alternative to 24-h urine more valid than overnight urine for ranking a person's electrolyte status. In a cross-sectional study of 40 young adults, two consecutive 24-h urine samples were collected, followed one month later by two further consecutive 24-h samples. Mean excretion rates of sodium and chloride steadily increased during the daytime. Electrolyte/creatinine ratios also increased, but all excretion rates decreased after sleep. The potassium excretion rate increased rapidly in the morning but declined steadily after 10 a.m.. Estimates of 24-h electrolyte content calculated from half-day amounts were approximately 80-92% of the actual 24-h urinary electrolyte values. Estimates obtained using overnight urine amounts approximated 60% of the actual 24-h values. Correlation coefficients between actual 24-h urinary electrolytes and estimates based on half-day urine were better than correlates between actual 24-h amounts and estimates obtained using timed overnight urine. These results suggest that half-day evening urine may be a useful alternative to 24-h urine for assessing electrolyte in-take.

Adult↗