Stability of ten serum tumor markers after one year of storage at -18°C.

OBJECTIVES: The storage of serum tumor markers (STM) at -18 °C for one year has been a legal requirement in France since 1999, but has been abolished in 2022. This raises the question of the relevance of maintaining these biobanks in terms of conditions of storage. These should only be implemented after validation; in order to maintain the integrity of the biological sample and must be controlled over time according to the laboratory's procedures. The aim of the study was to assess the suitability of storing 10 STMs by evaluating their stability after one year of storage at -18 °C. METHODS: A new immuno-enzymatic assay (A+1) was conducted on samples that had been stored at -18 °C for one year after an initial assay (A) of one of the following STMs: carcino-embryonic antigen (CEA), alpha-fetoprotein (AFP), carbohydrate antigen 125 (CA125), carbohydrate antigen 15-3 (CA15-3), carbohydrate antigen 19-9 (CA19-9), total (TPSA), and free (FPSA) prostate-specific antigen, calcitonin (CT), thyroglobulin (TG), and neuro-specific enolase (NSE). The results were confronted to four different permissible error sources. RESULTS: In total, 1148 A+1 assays were performed. A strong correlation between A+1 and A values was found for all analytes, but with a statistically significant reduction in the mean A+1 concentration compared to the mean A concentration in 7/10 STMs. The bias induced by conservation seems to be technically unsustainable if we rely on the repositories closest to the current analytical performances. CONCLUSIONS: These results support the discontinuation of mandatory STM biobank storage at -18 °C, which requires considerable technical time and organizational effort.

A new approach to assessing calcium status via a machine learning algorithm.

BACKGROUND AND AIMS: Calcium plays a fundamental role in biological processes. Ionized calcium (Ca2+), is the biologically active fraction, but in practice total or corrected calcium assays are routinely used to determine calcium status. MATERIALS AND METHODS: We retrospectively compared total and corrected calcium to assess the calcium status, with ionized calcium which is considered for now like the best indicator. To compensate for their lack of performance we created a machine learning algorithm to predict calcium status. RESULTS: Corrected calcium performed less well than total calcium with 58% and 74% agreement, respectively, in our population. Total calcium was especially good for hypocalcemic samples: 93% agreement versus 45% for normocalcemic and 54% for hypercalcemic samples. Corrected calcium was especially good for hypercalcemic and normocalcemic samples: 90% and 84% agreement respectively versus 40% for hypocalcemic samples. Corrected calcium is mainly faulty in hypoalbuminemia, acid-base disorders, renal insufficiency, hyperphosphatemia, or inflammatory syndrome. With our ML algorithm, we obtained 81% correct classifications. Its main advantage is that its performance are not influenced by the variables studied or the calcium status. CONCLUSION: In many situations, corrected calcium should not be used. Our ML algorithm may make a better assessment of calcium status than total calcium. Finally, if doubt, an ionized calcium assay should be performed.

Personalized dietary advices provided by a dietitian increase calcium intake in outpatients with multiple sclerosis-Results from a randomized, controlled, single-blind trial.

Background and aims: Multiple sclerosis (MS) is associated with osteoporosis, possibly due to neurological disability and decreased calcium intake. The objective of this study was to evaluate the efficacy of a personalized nutritional advice program by a dietitian compared to the delivery of a standard advice form to optimize dietary calcium intake in outpatients with MS. Methods: We performed a randomized, controlled, parallel trial comparing the efficacy of a personalized dietary advice (PDA) program to standard advice form (SAF) to increase daily calcium intake in MS patients. The study population was composed by patients with relapsing-remitting MS aged 18-69 years old. PDA program consisted in dietary advice delivered by a dietitian at baseline, 1 month, and 3 months. Calcium and nutrient intake in patients from both groups was evaluated at baseline and 6 months using a dietary survey. Results: Of the 194 patients screened for inclusion, 182 patients were included (79% female, median age of 42 years, and median EDSS of 2.0), and randomized to SAF (n = 92) or PDA (n = 90). At 6 months, median calcium intake increased by 241 mg/day in the PDA group and decreased by 120 mg/day in the SAF group (p < 0.0001). However, the median calcium intake was 947 mg/day in the SAF group and 778 mg/day in the PDA group at baseline (p = 0.0077), potentially favoring the effect of dietary advice. Complementary analyses focusing on patients with insufficient calcium intakes at baseline revealed comparable values in both groups (p = 0.69). Of those, patients included in the PDA group obtained significantly higher calcium intakes at 6 months than patients from the SAF group (p = 0.0086) independently of EDSS, PASAT, HADS and EQ-5D scores. Conclusion: This work shows the efficacy of dietary management based on personalized advice program over 3 months to durably increase calcium consumption in MS patients with insufficient calcium intake. Clinical trial registration: clinicaltrials.gov, identifier NCT02664623.