Endocrine Abstracts

Introduction: Primary adult-type lactose malabsorption (PALM) is a widespread inherited autosomal recessive condition. It is considered to be associated with osteoporosis. The purpose of the present study was to assess the 25-hydroxy-vitamin D (25[OH]D) status, serum CrossLaps and dairy calcium intake in individuals with PALM (i.e., LCT C/C₋₁₃₉₁₀ genotype) and normal controls (i.e., LCT C/T_-13910 and T/T₋₁₃₉₁₀ genotypes). In addition, the height, weight and body mass index (BMI) were determined.

Methods: In total, 210 adult individuals, who were referred to our outpatient clinic for PALM testing, were included in this prospective cross-sectional study. All participants underwent genotyping for the LCT C/T_-13910 polymorphism, 25(OH)D and CrossLaps measurements and clinical examinations. Blood sampling was performed after a 12 h overnight fasting in the morning between 8:00 and 10:00 h. A self-developed questionnaire was used to estimate daily calcium intake from dairy products.

Results: Fifty-five individuals with PALM (i.e., LCT C/C₋₁₃₉₁₀ homozygotes) showed significantly lower 25(OH)D (mean: 24.95±10.04 vs 28.59±9.56 ng/ml, P=0.018) and higher CrossLaps serum levels (mean: 0.46±0.31 vs 0.43±0.49 ng/ml, P=0.251) compared to 155 normal controls (i.e., LCT C/T_-13910 hetero- or T/T₋₁₃₉₁₀ homozygotes). Moreover, 26/55 (47.27%) LCT C/C_-13910 homozygotes reported to be lactose intolerant compared to 31/155 (20.0%) normal controls (P<0.001). Total dairy calcium intake (mean: 303±162 vs 330±194 mg/day, P=0.463) and anthropometric data were similar between PALM probands and controls.

Conclusion: In conclusion, individuals with PALM were found to have significantly lower 25(OH)D and higher CrossLaps serum levels compared to individuals with lactase-persistence. Based on these findings, we suggest to perform routine 25(OH)D and CrossLaps serum measurements in individuals with PALM. The determination of these biomarkers may contribute to the preservation of life-long bone health.