Sodium and Related Mineral Intake in Chronic Disease

2020-04-24T12:46:49Z (GMT) by Andrea J Lobene
The intake of sodium, potassium, and phosphorus has important implications for chronic disease risk. Excess sodium intake is shown to be associated with elevated blood pressure, which in turn is a risk factor for cardiovascular disease (CVD) and chronic kidney disease (CKD). Potassium intake, on the other hand, is shown to be beneficial for lowering blood pressure and reducing the risk of CVD and CKD. Once an individual develops CKD, they experience alterations in mineral metabolism, especially phosphorus, and must closely monitor mineral intake and biochemical laboratory values in order to avoid complications. Thus, monitoring mineral intake is important in both healthy and CKD individuals in both research as well as clinical practice settings. It is therefore also important to have a method for estimating mineral intake that is both accurate as well as easy to administer. Two commonly used methods are self-report and 24-hour urinary mineral excretion. however, both methods have pros and cons. An alternative option that has been explored for all three minerals of interest is to collect a spot urine sample, then use one of several published equations to calculate an estimate of 24-hour urinary mineral excretion. While this method is relatively easy to administer, much remains unexplored regarding the accuracy of estimated 24-hour mineral excretion. My aim for my dissertation was to explore how estimated 24-hour sodium (e24hUNa), potassium (e24hUK) and phosphorus (e24hUP) compared to true mineral intake in healthy participants as well as those with CKD. We conducted secondary analyses from two controlled feeding studies, in which true mineral intake was known. Our results show that e24hUNa and e24hUK are not reliable indicators of true sodium and potassium intake, respectively, in healthy participants nor those with CKD, and e24hUP is not a reliable indicator of phosphorus intake in CKD participants. Though these findings should be confirmed by larger studies, these findings suggest that currently available equations may need to be revised and estimated 24-hour mineral excretion from spot urine samples should be interpreted with caution.