August 1, 1965Circulation
A Method for the Detection and Quantification of Impaired Sodium Excretion
Why the study?
Does an oral sodium tolerance test detect and quantify impaired sodium excretion in patients with heart disease?
Population
n=54 total (13 normal subjects and 41 patients with heart disease)
Comparison
Oral sodium tolerance test vs Normal subjects
Design
Cross-sectional
Follow-up
12 days (4-day prep, 8-day test)
Authors
Discussion
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Implication
May identify impaired sodium excretion in heart disease; hypothesis-generating for functional assessment pending prospective validation.
Key Points
- To develop and evaluate an oral sodium tolerance test for detecting and quantifying impaired sodium excretion in patients with heart disease.
- Assessed 13 normal subjects and 41 patients with heart disease using an 8-day oral sodium loading protocol (10 mEq/day baseline for 4 days, followed by 80 mEq/day for 4 days and 150 mEq/day for 4 days; total 920 mEq, with a 320-mEq alternate protocol).
- Measured total 8-day urinary sodium excretion and analyzed associations with disease etiology, functional disability, edema history, glomerular filtration rate, and hemodynamic parameters.
- Normal subjects (N=13) excreted between 550 and 734 mEq of sodium, whereas 31 of 41 heart disease patients excreted subnormal amounts (10 to 550 mEq), and only 10 patients excreted normal amounts.
- Impaired sodium excretion did not correlate with cardiac etiology, glomerular filtration rate, or hemodynamics, but aligned with functional disability and edema, and improved following corrective cardiac surgery.
Structured PICO
Does an oral sodium tolerance test detect and quantify impaired sodium excretion in patients with heart disease?
P
Population
n=54 total (13 normal subjects and 41 patients with heart disease)
I
Intervention
Oral sodium tolerance test (daily Na intake limited to 10 mEq for 4 days, then 80 mEq daily for 4 days, then 150 mEq daily for 4 days; or alternate plan of 320 mEq over 8 days)
C
Comparator
Normal subjects
O
Outcome
Total urinary Na excretion during the 8-day test periodsurrogate
An oral sodium tolerance test effectively detects and quantifies impaired sodium excretion in patients with heart failure, which correlates with functional disability.
Cite This Study
Braunwald et al. (1965) studied this question.