Circadian Rhythm of Glomerular Filtration Rate in Normal Individuals

Koopman, M. G.; Koomen, G. C. M.; Krediet, R. T.; Moor, E; Hoek, Frans J.; Arisz, L.

doi:10.1042/cs0770105

Cited by 226 publications

(176 citation statements)

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“…Daytime creatinine clearance was lower in T1 subjects than in T2 and T3 subjects but rose at night instead of going down, as generally observed in normal subjects. 37 Differences in the fractional excretion of creatinine around the clock have been described 38 and probably result from variations in creatinine secretion and/or reabsorption.…”

Section: Bankir Et Al Blood Pressure and Daytime Sodium Excretionmentioning

confidence: 99%

“…Potassium usually exhibits variations in its excretion rate during daytime and nighttime that are of a much greater amplitude than the rates for other electrolytes and creatinine, and a large fraction of the total 24-hour potassium is excreted during daytime. 37 Recent studies in rats suggest that the beneficial effect of potassium on BP may be because of the fact that its secretion induces an increase in urine flow rate selectively during the active period (nighttime for rats but daytime for humans), thus enhancing the day:night ratio of the sodium excretion rate. 42 This study has some advantages and some limitations.…”

Section: Bankir Et Al Blood Pressure and Daytime Sodium Excretionmentioning

confidence: 99%

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Nighttime Blood Pressure and Nocturnal Dipping Are Associated With Daytime Urinary Sodium Excretion in African Subjects

et al. 2008

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Abstract-Blood pressure (BP) follows a circadian rhythm, with 10% to 15% lower values during nighttime than during daytime. The absence of a nocturnal BP decrease (dipping) is associated with target organ damage, but the determinants of dipping are poorly understood. We assessed whether the nighttime BP and the dipping are associated with the circadian pattern of sodium excretion. Ambulatory BP and daytime and nighttime urinary electrolyte excretion were measured simultaneously in 325 individuals of African descent from 73 families. When divided into sex-specific tertiles of day:night ratios of urinary sodium excretion rate, subjects in tertile 1 (with the lowest ratio) were 6.5 years older and had a 9.8-mm Hg higher nighttime systolic BP (SBP) and a 23% lower SBP dipping (expressed in percentage of day value) compared with subjects in tertile 3 (P for trend Ͻ0.01). After adjustment for age, the SBP difference across tertiles decreased to 5.4 mm Hg (Pϭ0.002), and the SBP dipping difference decreased to 17% (Pϭ0.05). A similar trend across tertiles was found with diastolic BP. In multivariate analyses, daytime urinary sodium and potassium concentrations were independently associated with nighttime SBP and SBP dipping (PϽ0.05 for each). These data, based on a large number of subjects, suggest that the capacity to excrete sodium during daytime is a significant determinant of nocturnal BP and dipping. This observation may help us to understand the pathophysiology and clinical consequences of nighttime BP and to develop therapeutic strategies to normalize the dipping profile in hypertensive patients. (Hypertension. 2008;51:891-898.)

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Section: Bankir Et Al Blood Pressure and Daytime Sodium Excretionmentioning

confidence: 99%

Section: Bankir Et Al Blood Pressure and Daytime Sodium Excretionmentioning

confidence: 99%

Nighttime Blood Pressure and Nocturnal Dipping Are Associated With Daytime Urinary Sodium Excretion in African Subjects

et al. 2008

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“…Since the data were derived using first or second generation assays, it is possible that the reported diurnal variation of PTH could reflect differential clearance of PTH fragments over a 24 h period, e.g., with reduced renal clearance of (7-84) PTH at night reflecting decreased glomerular filtration rate at night [92].…”

Section: Circadian Variationmentioning

confidence: 99%

Sampling and storage conditions influencing the measurement of parathyroid hormone in blood samples: a systematic review

Hanon

Sturgeon

Lamb

2013

Clinical Chemistry and Laboratory Medicine (CCLM)

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Parathyroid hormone (PTH) is relatively unstable: optimisation of pre-analytical conditions, including specimen type, sampling time and storage conditions, is essential. We have undertaken a systematic review of these pre-analytical conditions. An electronic search of the PubMed, Embase, Cochrane, Centre for Research and Dissemination and Bandolier databases was undertaken. Of 5511 papers identified, 96 underwent full text review, of which 83 were finally included. At room temperature PTH was stable in ethylenediaminetetraacetic acid (EDTA) preserved whole blood for at least 24 h and in EDTA plasma for at least 48 h after venepuncture. Losses were observed in clotted blood samples after 3 h and in serum after 2 h. At 4°C PTH was more stable in EDTA plasma (at least 72 h) than serum (at least 24 h). Central venous PTH concentrations were higher than peripheral venous concentrations. In the northern hemisphere, PTH concentrations were higher in winter than summer. PTH has a circadian rhythm characterised by a nocturnal acrophase and mid-morning nadir. Data related to frozen storage of PTH (−20°C and −80°C) were limited and contradictory. We recommend that blood samples for PTH measurement should be taken into tubes containing EDTA, ideally between 10:00 and 16:00, and plasma separated within 24 h of venepuncture. Plasma samples should be stored at 4°C and analysed within 72 h of venepuncture. Particular regard must be paid to the venepuncture site when interpreting PTH concentration. Further research is required to clarify the suitability of freezing samples prior to PTH measurement.

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“…First, and the most important limitation, is the inaccuracy of the urine volume. Second, the occurrence of circadian variations secondary to urine filtration and tubular secretion or reabsorption may introduce other estimate deviations besides those secondary to urine collection (54) . Finally, in large epidemiological studies conducted on the general population, measuring urine produced over 24 h is challenging because specimens must be collected and stored during working periods.…”

Section: Discussionmentioning

confidence: 99%

Relationship between 24 h urinary potassium and diet quality in the adult Spanish population

Rodríguez-Rodríguez

Ortega

Carvajales

et al. 2014

Public Health Nutr.

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Objective: To study the relationship between diet quality and 24 h urinary K excretion. Design: K was measured in 24 h urine samples, while diet was studied using a 24 h recall method over two consecutive days. Diet quality was determined using the Healthy Eating Index (HEI). The body weight, height and body composition of all participants were recorded, and the BMI of each calculated. Setting: Representative members of the adult Spanish population from the FANPE Study ('Fuentes Alimentarias de Nutrientes en Población Española'; Dietary Sources of Nutrients in the Spanish Population). Subjects: The final sample size was 329 participants aged 18-60 years. Results: Participants with a 24 h urinary K excretion ≥ 93 mmol/d (group AP = adequate potassium) had greater self-reported K intakes, consumed more fruit and vegetables, had a more varied diet and had better HEI scores than those with a 24 h urinary K excretion < 93 mmol/d (group IP = inadequate potassium). A significant positive correlation was seen between 24 h urinary K and dietary variety and the number of servings of fruits, vegetables and dairy products consumed, and between each of these and the HEI after correcting for age, sex, BMI, coefficient of activity, energy intake and the under-reporting of energy intake. AP participants were less likely to have an inadequate diet (HEI score < 50) than IP participants (OR = 0·439; 95 % CI 0·201, 0·961; P = 0·039). Conclusions: Diet quality, measured by the HEI, is correlated with 24 h urinary K excretion in Spanish adults.

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Circadian Rhythm of Glomerular Filtration Rate in Normal Individuals

Cited by 226 publications

References 0 publications

Nighttime Blood Pressure and Nocturnal Dipping Are Associated With Daytime Urinary Sodium Excretion in African Subjects

Nighttime Blood Pressure and Nocturnal Dipping Are Associated With Daytime Urinary Sodium Excretion in African Subjects

Sampling and storage conditions influencing the measurement of parathyroid hormone in blood samples: a systematic review

Relationship between 24 h urinary potassium and diet quality in the adult Spanish population

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