Sodium and potassium intakes in a representative population sample: estimation from 24 h urine collections known to be complete in a Cambridgeshire village

Objective and design: The study comprised three protocols. Protocol 1 compared a HPLC method with the commonly employed colorimetric diazocoupling method. Protocol 2 examined, if the last dosage of paminobenzoic acid (PABA) could be advanced in the old to allow for a delayed age-dependent urinary excretion of PABA. Protocol 3 established limits for recovery of PABA in 24 h urine applying the HPLC method. Subjects and setting: A total of 151 healthy volunteers participated in the study of which 140 were accepted. In protocol 1: 37 subjects aged 20±78 y were included. All subjects took PABA as recommended (80 mg orally at 08.00, 12.00 and 18.00 h). Protocol 2: compared urinary PABA excretion in two groups of 80 y old subjects who had their last PABA dosage administered at 15.00 h (n 16) and at 18.00 h (n 31), respectively. Protocol 3: comprised 56 subjects aged 20±80 y. In the younger age group (20±59 y; n 34) PABA was taken as recommended, whereas in the older age group (60±80 y; n 22) the last PABA dosage was advanced three hours. Results: Protocol 1: HPLC gave signi®cantly lower PABA recovery results compared to colorimetry, the difference between methods being 23.9 AE 8.5 mg/24 h (P`0.001). Protocol 2: higher PABA recoveries were demonstrated with the advanced dosage schedule compared to the recommended schedule (208 AE 14 mg/24 h vs 181 AE 22 mg/24 h; P`0.001). Protocol 3: PABA recovery with HPLC was 211 AE 12 mg/24 h, and the lower limit comprising 95% of subjects was 187 mg/24 h. Similar PABA recoveries were demonstrated in the younger subjects and the older subjects (211 AE 11 mg/24 h vs 211 AE 13 mg/24 h; NS). Conclusion: An advanced dosage schedule for PABA in the aged is recommended. Because of lower recoveries with HPLC, the low limit for recovered PABA in a complete 24 h urine differs from the limit based on colorimetry. This study found a limit of 187 mg/24 h corresponding to the lower 95% con®dence limit for a single subject.

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“…The procedure was that described by Williams & Bingham (1986)). A Shimadzu UV 160-A (Kyoto, Japan) spectrophotometer was used.…”

Section: Methodsmentioning

confidence: 99%

para-aminobenzoic acid used as a marker for completeness of 24 hour urine: assessment of control limits for a specific HPLC method

Jakobsen¹,

Ovesen²,

Fagt³

et al. 1997

Eur J Clin Nutr

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“…Unfortunately, there is no suitable marker available to check for the completeness of urine collections. p-Aminobenzoic acid has been used as a quantitative urine control marker (52)(53)(54), but its safety has been questioned (55). The use of creatinine as a quantitative control marker has low sensitivity, particularly in older age groups (53,56).…”

Section: Discussionmentioning

confidence: 99%

Measurement of magnesium absorption and retention in type 2 diabetic patients with the use of stable isotopes

Wälti

Zimmermann

Walczyk

et al. 2003

The American Journal of Clinical Nutrition

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Background: Magnesium deficiency has been associated with type 2 diabetes and may reduce insulin sensitivity and impair glucose tolerance. The etiology of magnesium depletion in diabetes is unclear. Animal studies suggest that diabetes may impair magnesium absorption; however, there are no published data on magnesium absorption in humans with diabetes. Objective: Magnesium absorption from a test meal and the excretion and retention of magnesium were compared between patients with type 2 diabetes and healthy control subjects. Design: A meal labeled with 10 mg 26 Mg isotopic label was administered, and stool and urine samples were collected for 10 and 6 d, respectively. Apparent absorption was calculated as the difference between the oral dose of 26 Mg isotopic label and the total amount of the isotopic label excreted in the feces. Magnesium retention was calculated from the apparent absorption and urinary excretion of 26 Mg isotopic label in the 6 d after administration. Results: Mean (± SD) values for fractional magnesium absorption in the diabetic patients and the control subjects were 59.3 ± 7.0% and 57.6 ± 8.5%, respectively (NS). Mean (± SD) urinary magnesium excretion values in the diabetic patients and the control subjects were 11.2 ± 2.6% and 11.7 ± 3.8%, respectively (NS); retention values were 54.2 ± 7.1% and 51.4 ± 6.1%, respectively (NS). Conclusion: Dietary magnesium absorption and retention are not impaired in patients with reasonably well-controlled type 2 diabetes.Am J Clin Nutr 2003;78:448-53.

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“…More recently, the use of an inert indicator, paraaminobenzoic acid (PABA) has been suggested to docu ment food intake [44] and urine collections [34,35,45,46] in studies such as these. It has a 3-8-hr recovery rate [34], and, in continuous samples, nearly 100% should be recovered in urine [35].…”

Section: Discussionmentioning

confidence: 99%

Feasibility of outpatient electrolyte balance studies.

McCullough

Swain

Malarick

et al. 1991

Journal of the American College of Nutrition

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Clinical studies requiring controlled electrolyte balance have traditionally been conducted in an inpatient (IP), metabolic ward setting. The purpose of this study was to test the feasibility of performing such studies in an outpatient (OP) clinical research setting. Focusing on sodium (Na) and potassium (K) balance, we retrospectively compared 28 subjects studied as OP vs 25 studied as IP on our metabolic ward. We assessed their adherence to our metabolic diets and their compliance with serial 24-hr urine collections. Dietary compliance was assessed by checksheet and urinary Na excretion; urine collection accuracy was determined by serial 24-hr creatinine excretion. The diets for both studies contained a low Na phase (10 mEq) and a high Na phase (200 mEq for IP and 250 mEq for OP), each lasting 1 week. When in balance on the low Na diet, 24-hr Na excretion was 4.6 +/- 0.7 mEq for OP and 13.4 +/- 2.2 mEq for IP, indicating excellent compliance with the low salt diet. Na excretion on the high Na diet was 184.5 +/- 7.4 mEq for OP and 195.3 +/- 9.6 mEq for IP. These values were not significantly different from each other; however, the OP were significantly less than their diet of 250 mEq Na (p less than 0.05). This difference may have been due to dermal Na losses. K excretion was also similar in the two groups. There was no significant difference in the reproducibility of individual multiple urinary creatinine measurements in OP vs IP.(ABSTRACT TRUNCATED AT 250 WORDS)

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Sodium and potassium intakes in a representative population sample: estimation from 24 h urine collections known to be complete in a Cambridgeshire village

Cited by 32 publications

References 10 publications

para-aminobenzoic acid used as a marker for completeness of 24 hour urine: assessment of control limits for a specific HPLC method

para-aminobenzoic acid used as a marker for completeness of 24 hour urine: assessment of control limits for a specific HPLC method

Measurement of magnesium absorption and retention in type 2 diabetic patients with the use of stable isotopes

Feasibility of outpatient electrolyte balance studies.

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