Para-aminobenzoic acid (PABA) used as a marker for completeness of 24 hour urine: effects of age and dosage scheduling

Jakobsen et al., 2003 | Eur J Clin Nutr | Rct

Citation

Jakobsen J, Pedersen A N, Ovesen L. Para-aminobenzoic acid (PABA) used as a marker for completeness of 24 hour urine: effects of age and dosage scheduling. Eur J Clin Nutr. 2003-Jan;57(1):138-42

Abstract

OBJECTIVE: To examine the age dependency of the urinary para-aminobenzoic acid (PABA) excretion, and if a delayed PABA excretion can be overcome by advancing intake schedule; and to examine the recovery of PABA in fractionated urinary samples collected during 24 h after single and repeated doses of PABA. DESIGN: Cross-over study with subjects randomized to start with recommended schedule of PABA administration (80 mg at 08:00, 12:00 and 18:00; PABA18) and then an advanced schedule (80 mg at 08:00, 12:00 and 15:00; PABA15) or vice versa. One subgroup of eight subjects collected individual urine specimens for 24 h after a morning dose of 80 mg of PABA, and another subgroup of 10 subjects collected individual urine specimens for 24 h after ingestion of 80 mg of PABA three times at mealtimes. SUBJECTS: Employees and relatives from the Danish Food Administration. SETTING: Ninety-nine healthy volunteers (61 females and 38 males) aged 30-91 y. RESULTS: Linear regressions for PABA15 and PABA18 demonstrate significantly less recovery with age (PABA15: r(2)=0.1784, P=0.0002; PABA18: r(2)=0.1273, P=0.0019). Linear regression of DeltaPABA (PABA15-PABA18) with age showed the best fit line to be horizontal (slope -0.0066, P=0.89; 95% CI -0.1046, 0.0915) and with a Y-intercept not significantly different from 0 (1.575; 95% CI -4.176, 7.326). In this population the lower limit for complete 24 h urine collection was 79.2%. After a single dosage of 80 mg PABA 70-85% was recovered after 8 h. Within 16 h after ingestion of 240 mg PABA at recommended hours the lowest acceptable recovery (78.1%) was reached. CONCLUSION: There is a gradual decline of PABA recovery with age that cannot be overcome by advancing the dosage schedule. Because of a lower delimiting PABA recovery for the elderly, some 24 h collections in this age group will be rejected unjustly (false-negatives). Also, with the currently recommended dosage schedule (PABA taken with the main meals) the risk of false-positive 24 h urine collections prevails. With refinement of the PABA test procedure, ie employing a specific analytical method and age-dependent cut-off values, the test may achieve a higher specificity and sensitivity.

Key Findings

Linear regressions for PABA15 and PABA18 demonstrate significantly less recovery with age (PABA15: r(2)=0.1784, P=0.0002; PABA18: r(2)=0.1273, P=0.0019). Linear regression of DeltaPABA (PABA15-PABA18) with age showed the best fit line to be horizontal (slope -0.0066, P=0.89; 95% CI -0.1046, 0.0915) and with a Y-intercept not significantly different from 0 (1.575; 95% CI -4.176, 7.326). In this population the lower limit for complete 24 h urine collection was 79.2%. After a single dosage of 80 mg

Outcomes Measured

• Requires manual extraction

Population

MeSH Terms

• 4-Aminobenzoic Acid
• Adult
• Age Factors
• Aged
• Aged, 80 and over
• Aging
• Biomarkers
• Chromatography, High Pressure Liquid
• Cross-Over Studies
• Drug Administration Schedule
• False Negative Reactions
• Female
• Humans
• Linear Models
• Male
• Metabolic Clearance Rate
• Middle Aged
• Sensitivity and Specificity
• Time Factors

Evidence Classification

• Level: Rct
• Publication Types: Clinical Trial, Journal Article, Randomized Controlled Trial
• Vertical: paba

Provenance

• PMID: 12548308
• DOI: (not available)
• PMCID: Not in PMC
• Verified: 2026-04-12 via PubMed E-utilities API

Source extracted via PubMed E-utilities API on 2026-04-12