Achieving Salt Restriction in Chronic Kidney Disease

Table 1

Summary of measures that can be used to estimate sodium intake.

Measure	Objectivity	Burden	Strengths	Limitations
24-hour urinary sodium	Objective	High	(i) Gold standard; (ii) Accurately quantifies actual intake when collected correctly	(i) Under/overcollection can introduce error; (ii) High participant burden; (iii) High cost of analysis; (iv) Does not account for daily variation
Spot urinary sodium	Objective	Low	(i) Low participant burden; (ii) Quick to collect; (iii) Can be used as part of standard practice	(i) Does not account for diurnal variation; (ii) Further research needed to determine if valid indicator of daily intake
Open-ended diet history	Self-report	Moderate	(i) Most comprehensive of self-reported measures; (ii) Presence of interviewer allows for verification and clarification of information provided; (iii) Retrospective nature allows for assessment of “usual intake”	(i) Time consuming to collect and code; (ii) Prone to memory lapse and reporting bias; (iii) Specialized skills and knowledge of food supply required
24-hour recall	Self-report	Low	(i) Standardized; (ii) Can be implemented over the phone; (iii) Multiple administrations increases validity; (iv) Best for larger population-based studies	(i) Does not account for daily variation in intake (unless repeated); (ii) Prone to reporting bias
Food records; (diaries)	Self-report	Depends on number of days	(i) Precise estimation of actual intake on the days where recording occurs, when completed correctly	(i) Subject to participant motivation; (ii) Increased number of days increases participant burden; (iii) Prone to under-reporting; (iv) Prone to modification of intake on days where recording occurs
Food frequency questionnaire	Self-report	Low	(i) Standardized; (ii) Quick to administer; (iii) Easily coded; (iv) Many validation studies	(i) Validity can depend on population in question and food supply.; (ii) Subject to memory lapse; inability to summarize intake; false perception of own intake.; (iii) Collects information about a limited number of foods; (iv) Difficult to measure discretionary salt usage