URI-Minder

Introduction

Timed 24-hour urine collection is useful for evaluating kidney function (creatinine clearance), quantifying proteinuria as part of CKD assessment and monitoring response to treatment of various glomerulopathies, assessing metabolic risk factors for nephrolithiasis (calcium, oxalate, uric acid, and citrate), estimating dietary intake of minerals (sodium and potassium), and helping to diagnose endocrine disorders (e.g., cortisol metabolites and catecholamines). Incomplete collections due to patient forgetfulness or procedural errors are a persistent challenge, leading to frequent underestimation of the amounts of analytes excreted and inaccurate diagnoses. Urine collections may be incomplete, often because patients forget to collect one or more voids, particularly during nighttime or busy periods.¹ This issue is compounded when patients fail to report that not all urine was collected during a 24-hour period, because this can result in erroneous clinical decisions.

The reliability of 24-hour urine collections hinges on patients collecting every void over a 23- to 25-hour period, with accurate recording of start and end times. Studies consistently report that incomplete collections are common, with rates ranging from 6% to 47% on the basis of para-aminobenzoic acid (PABA) validation across eight studies.¹ For example, Knuiman et al. found significant variability in collection completeness across 11 European centers, with creatinine and PABA markers revealing missed voids.² Similarly, Mann and Gerber reported that 36 of 99 collections were incomplete on the basis of expected creatinine excretion, highlighting the scale of the problem.³ Patients typically urinate 4–10 times daily, and forgetting even one void can skew results. Williams and Bingham noted that incomplete collections underestimated sodium and potassium excretion in a population study, affecting dietary assessments.⁴ Leclercq et al. further demonstrated that older and outpatient populations are particularly prone to errors, often because of inadequate reminders or understanding of the protocol.⁵ Comparison of the amount of creatinine excreted in the 24-hour sample with expected values on the basis of age, weight, height, sex, and race can be used to assess collection completeness. Another method is to study the percent recovery of orally administered PABA. Murakami et al. reported that creatinine-based strategies have low sensitivity and specificity for detecting incomplete collections,⁶ whereas Subar et al. argued that PABA validation is unnecessary in some contexts because of its complexity.⁷

Incomplete collections lead to underestimation of key analytes, affecting diagnoses and treatment. For example, Mattix et al. highlighted that inaccurate collections compromise microalbuminuria detection, with implications for sex-specific and race-specific thresholds.⁸ Incomplete collections in patients with lupus nephritis can underestimate proteinuria, delaying treatment adjustments. In the workup for causes of nephrolithiasis, Borghi et al. showed that missed voids skew metabolic profiles, potentially increasing stone recurrence risk.⁹

These challenges highlight the need for interventions to improve patient adherence and collection accuracy, particularly in outpatient settings where most 24-hour collections occur.

The URI-Minder Kit: Design and Functionality

The URI-minder, a memory-jogging kit, was designed to address this challenge.¹⁰ By incorporating tactile and visual reminders (shields, stickers, or temporary tattoos) that patients encounter just before urination, the URI-minder is designed as an economical add-on packet of reminder tools designed to help ensure consistent collection of all urine samples during a 24-hour period. The kit is packaged in a lightweight clear plastic envelope, with an estimated cost of fewer than $5, and is designed to be given to the patient along with the urine collection container.

The kit includes three components, each providing a tactile or visual reminder to collect urine, and detailed instructions to patients for how to properly collect their 24-hour urine sample:

1. Tactile undergarment shield: This is a thin, soft plastic shield with a folded tab that hooks over the waistband of the undergarment (Figure 1). For men, the shield is larger because it is designed to cover the area between the underpants and the fly-opening. When a man goes to urinate without lowering his pants, on opening his fly by undoing his zipper, his fingers encounter the soft plastic shield instead of his underpants, and this tactile surprise serves to briefly interrupt the process of micturition, reminding the person that urine collection is in progress and that he should make sure to urinate into the collection container. For women, the soft plastic shield is considerably smaller in size, but the shield also hooks over the waistband of the undergarment. The shield is smaller for women because there is no need for it to cover the pubic area. For both men who urinate sitting down on the toilet and for women, the shield will become visible on lowering one's pants as one sits on the toilet, in this case, serving as a visual reminder that any expelled urine must be placed in the collection container. The shield is made of soft plastic without sharp edges to minimize the chances of pressure injury to the genital region.

2. Message-in-a-bottle stickers: In the URI-minder kit, there are several stickers with a logo showing a message in a bottle. For situations where the bathroom is in a private home, the stickers can be applied to the toilet seat or tank or any other place where they will be encountered in the process of micturition. This is especially useful at night, to remind patients who get up in the middle of the night, to route any urine output they produce into the collection bottle.

3. Washable temporary tattoos: A third set of reminder tools are washable temporary tattoos, again, showing a message in a bottle. The tattoos can be applied to the upper thighs. This reminder logo will become visible when the patient sits at the toilet to urinate. The dyes used in the water-soluble tattoos should be limited to those approved by the US Food and Drug Administration for cosmetic use, to minimize the risk of skin irritation or allergy.

Figure 1.

Urinary reminder system (URI-minder). The soft plastic shields for men (top row) and women (middle row) are shown. Left column: how to apply the shield to the undergarment by folding a tab over the waistband. Right column: shield in place. In men, the shield is encountered on opening the fly, serving to jog the memory about the need to collect every urine sample. In both sexes who urinate sitting down on the toilet, the shield becomes visible on sitting down after lowering one's pants. The bottom panel shows the complete URI-minder kit (prototype manufactured by Molded Products, Inc., Harlan, IA). The kit is intended to be supplied with the urine collection container.

A fourth component of the URI-minder kit is a detailed set of instructions regarding how one should initiate the 24-hour urine collection. The kit includes a card for recording start and stop collection times.

Discussion

As described above, the URI-minder kit as presently configured contains three different types of reminders, one tactile and two visual. Each component may be more or less effective in a reminder function, depending on the circumstances of where urine is collected. The tactile reminder pads may be more effective in men normally urinating while standing (on encountering the pad when opening the zipper of one's pants) compared with women or men who normally lower their undergarments and then urinate while sitting down on the toilet.

The URI-minder memory-jogging kit has the potential to improve the reliability of 24-hour urine collections by addressing patient forgetfulness, a key barrier to accurate diagnostics in this area of measurement. It should be noted that the efficacy of this kit in reducing the incidence of incomplete urine collections has not been evaluated in a controlled study.

The need to improve timed urine collections was highlighted after my own failure to properly collect three sequential 24-hour urines for workup of kidney stones, followed by success in completing the collections when using the described method. The purpose of describing this method is to encourage evaluation of this technique to mitigate a problem area to which very little attention has been paid.

Disclosures

Disclosure forms, as provided by each author, are available with the online version of the article at http://links.lww.com/JSN/F522.

Author Contributions

Conceptualization: John T. Daugirdas.

Methodology: John T. Daugirdas.

Supervision: John T. Daugirdas.

Writing – original draft: John T. Daugirdas.

Writing – review & editing: John T. Daugirdas.

Funding

None.