C-terminal telopeptide of type I collagen, osteocalcin, alkaline phosphatase, and parathyroid hormone in healthy and hospitalized foals

Assessing causal associations of hyperparathyroidism with blood counts and biochemical indicators: a Mendelian randomization study

Background

The existing literature on the relationship of hyperparathyroidism with both blood counts and biochemical indicators primarily comprises observational studies, which have produced inconsistent findings. This study aimed to evaluate the causal relationship between hyperparathyroidism and blood counts and biochemical indicators.

Methods

Mendelian randomization (MR) analyses were conducted to investigate the associations between hyperparathyroidism and the identified 55 blood counts and biochemical indicators. The genome-wide association study (GWAS) for hyperparathyroidism data was obtained from FinnGen, while the GWASs for the blood counts and biochemical indicators were sourced from the UK Biobank (UKBB).

Results

The MR analysis using the inverse-variance weighted (IVW) method revealed potential causality between genetically predicted hyperparathyroidism and seven out of 55 blood counts and biochemical indicators. These markers include "Platelet count" (Beta = -0.041; 95% CI: -0.066, -0.016; p = 0.001), "Platelet distribution width (PDW)" (Beta = 0.031; 95% CI: 0.006, 0.056; p = 0.016), "Mean platelet volume (MPV)" (Beta = 0.043; 95% CI: 0.010, 0.076; p = 0.011), "Vitamin D" (Beta = -0.038; 95% CI: -0.063, -0.013; p = 0.003), "Calcium (Ca2+)" (Beta = 0.266; 95% CI: 0.022, 0.509; p = 0.033), "Phosphate" (Beta = -0.114; 95% CI: -0.214, -0.014; p = 0.025), and "Alkaline phosphatase (ALP)" (Beta = 0.030; 95% CI: 0.010, 0.049; p = 0.003).

Conclusion

The findings of our study revealed a suggestive causal relationship between hyperparathyroidism and blood cell count as well as biochemical markers. This presents a novel perspective for further investigating the etiology and pathological mechanisms underlying hyperparathyroidism.

Serum bone metabolism biomarkers in healthy filies and colts from weaning until one year of age

This study aimed to investigate the serum concentration of osteocalcin (OC), parathyroid hormone (PTH), calcitonin (CT), calcium (Ca), phosphorus (P), alkaline phosphatase (ALP) and acid phosphatase (AP) in healthy-weaned-foals from 8 months of age until the first year of life. Moreover, the correlation of investigated parameters and foals' age, as well as the relationship between the serum values of PTH and the other markers of bone remodeling were assessed. From 20 foals (10 fillies, 10 colts), blood samples were monthly collected (from 8 to 12 months of age, T1-T5) and the concentration of OC, CT, Ca, P, ALP, AP and PTH was assessed. Two-way repeated measures analysis of variance (ANOVA) showed age-related differences on OC concentration in both fillies (P = 0.008) and colts (P = 0.03) with higher OC values at T5 than T1 and T2. Sex-related effect on OC concentration was found with higher OC levels in colts compared to fillies (P = 0.01). A significant positive correlation between the OC, PTH, CT and APL values and foal's age was found in fillies and colts. PTH levels were positively correlated with the values of OC in fillies and colts. Obtained findings confirmed the dynamic bone turnover during growth in foals. The modification of PTH and OC confirmed the potential role of these parameters as indicator of bone growth and metabolism. The sex-related difference observed in OC concentration opens up new insights into the possible involvement of sex hormones in the regulation of bone metabolism in prepubertal foals.

The enteroinsular axis during hospitalization in newborn foals

The enteroinsular axis (EIA) is an energy regulatory system that modulates insulin secretion through the release of enteroendocrine factors (incretins). Despite the importance of energy homeostasis in the equine neonate, information on the EIA in hospitalized foals is lacking. The goals of this study were to measure serum insulin and plasma incretin (glucose-dependent insulinotropic polypeptide [GIP], glucagon-like peptide-1 [GLP-1] and glucagon-like peptide-2 [GLP-2]) concentrations, to determine the insulin and incretin association, as well as their link to disease severity and outcome in hospitalized foals. A total of 102 newborn foals ≤72 h old were classified into hospitalized (n = 88) and healthy groups (n = 14). Hospitalized foals included septic (n = 55) and sick non-septic (SNS; n = 33) foals based on sepsis scores. Blood samples were collected over 72 h to measure serum insulin and plasma GIP, GLP-1 and GLP-2 concentrations using immunoassays. Data were analyzed by nonparametric methods and univariate logistic regression. At admission, serum glucose and insulin and plasma GIP were significantly lower in hospitalized and septic compared to healthy foals (P < 0.01), while plasma GLP-1 and GLP-2 concentrations were higher in hospitalized and septic foals than healthy and SNS foals, and decreased over time in septic foals (P < 0.05). As a percent of admission values, GLP-1 and GLP-2 concentrations dropped faster in healthy compared to hospitalized foals. Serum insulin concentrations were lower in hospitalized and septic non-survivors than survivors at admission (P < 0.01). Hospitalized foals with serum insulin < 5.8 µIU/mL, plasma GLP-1 >68.5 pM, and plasma GLP-2 >9 ng/mL within 24 h of admission were more likely to die (OR = 4.2; 95% CI = 1.1-16.1; OR = 13.5, 95% CI = 1.4-123.7; OR = 12.5, 95% CI = 1.6-97.6, respectively; P < 0.05). Low GIP together with increased GLP-1 and GLP-2 concentrations indicates that different mechanisms may be contributing to reduced insulin secretion in critically ill foals, including impaired intestinal production (GIP, proximal intestine) and pancreatic endocrine resistance to enhanced incretin secretion (GLP-1, GLP-2; distal intestine). These imbalances could contribute to energy dysregulation in the critically ill equine neonate.